/* ============================================================
   WATT CALCULATOR — Premium Design System
   ============================================================ */

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Dark Theme (default) - High Contrast & Crisp Accessibility */
  --bg-primary: #09090f;
  --bg-secondary: #11111b;
  --bg-card: rgba(22, 22, 36, 0.96);
  --bg-card-hover: rgba(30, 30, 48, 0.98);
  --bg-input: #171728;
  --bg-input-focus: #1f1f35;
  --border-card: rgba(255, 255, 255, 0.12);
  --border-input: rgba(255, 255, 255, 0.2);
  --border-input-focus: rgba(140, 120, 255, 0.75);
  --text-primary: #ffffff;
  --text-secondary: #d0d0e2;
  --text-muted: #a2a2bc;
  --accent-primary: #8b7aff;
  --accent-secondary: #5ee7df;
  --accent-warning: #ffa05c;
  --accent-gradient: linear-gradient(135deg, #8b7aff 0%, #5ee7df 50%, #ffa05c 100%);
  --accent-gradient-2: linear-gradient(135deg, #8b7aff 0%, #c471f5 100%);
  --glow-primary: rgba(139, 122, 255, 0.25);
  --glow-secondary: rgba(94, 231, 223, 0.2);
  --shadow-card: 0 4px 32px rgba(0, 0, 0, 0.5), 0 1px 3px rgba(0, 0, 0, 0.4);
  --shadow-elevated: 0 20px 60px rgba(0, 0, 0, 0.6), 0 4px 12px rgba(0, 0, 0, 0.4);
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'SF Mono', 'Fira Code', monospace;
  --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 300ms cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 400ms cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Card accent colours - Boosted Luminance for Readability */
  --voltage-color: #9d8eff;
  --voltage-glow: rgba(139, 122, 255, 0.22);
  --current-color: #5ee7df;
  --current-glow: rgba(94, 231, 223, 0.2);
  --resistance-color: #ffa05c;
  --resistance-glow: rgba(255, 160, 92, 0.2);
  --power-color: #f582e6;
  --power-glow: rgba(245, 130, 230, 0.2);
}

/* Light theme - High Contrast */
[data-theme="light"] {
  --bg-primary: #f6f7fb;
  --bg-secondary: #ebedf5;
  --bg-card: #ffffff;
  --bg-card-hover: #f9faff;
  --bg-input: #f0f1f8;
  --bg-input-focus: #ffffff;
  --border-card: rgba(0, 0, 0, 0.12);
  --border-input: rgba(0, 0, 0, 0.22);
  --border-input-focus: rgba(120, 100, 255, 0.7);
  --text-primary: #0d0f18;
  --text-secondary: #2f3245;
  --text-muted: #585b72;
  --glow-primary: rgba(124, 106, 255, 0.15);
  --glow-secondary: rgba(94, 231, 223, 0.12);
  --shadow-card: 0 4px 24px rgba(0, 0, 0, 0.08), 0 1px 3px rgba(0, 0, 0, 0.05);
  --shadow-elevated: 0 12px 40px rgba(0, 0, 0, 0.12), 0 4px 12px rgba(0, 0, 0, 0.06);
}

/* ---------- Global Reset & Base ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* ---------- Animated Background ---------- */
.bg-orbs {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(100px);
  opacity: 0.4;
  animation: float 20s ease-in-out infinite;
}

[data-theme="light"] .orb {
  opacity: 0.2;
  filter: blur(120px);
}

.orb-1 {
  width: 500px;
  height: 500px;
  background: var(--voltage-color);
  top: -10%;
  left: -5%;
  animation-delay: 0s;
}

.orb-2 {
  width: 400px;
  height: 400px;
  background: var(--current-color);
  top: 50%;
  right: -10%;
  animation-delay: -5s;
  animation-duration: 25s;
}

.orb-3 {
  width: 350px;
  height: 350px;
  background: var(--power-color);
  bottom: -5%;
  left: 30%;
  animation-delay: -10s;
  animation-duration: 22s;
}

.orb-4 {
  width: 300px;
  height: 300px;
  background: var(--resistance-color);
  top: 25%;
  left: 60%;
  animation-delay: -15s;
  animation-duration: 28s;
}

@keyframes float {

  0%,
  100% {
    transform: translate(0, 0) scale(1);
  }

  25% {
    transform: translate(40px, -60px) scale(1.05);
  }

  50% {
    transform: translate(-30px, 40px) scale(0.95);
  }

  75% {
    transform: translate(50px, 20px) scale(1.03);
  }
}

/* Grain overlay */
.grain-overlay {
  position: fixed;
  inset: 0;
  z-index: 1;
  pointer-events: none;
  opacity: 0.02;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
}

[data-theme="light"] .grain-overlay {
  opacity: 0.03;
}

/* ---------- Header ---------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  background: rgba(10, 10, 15, 0.7);
  border-bottom: 1px solid var(--border-card);
  transition: background var(--transition-smooth);
}

[data-theme="light"] .site-header {
  background: rgba(244, 244, 248, 0.75);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 700;
  font-size: 1.25rem;
  letter-spacing: -0.02em;
  transition: transform var(--transition-fast);
}

.logo:hover {
  transform: translateY(-1px);
}

.logo-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  flex-shrink: 0;
  transition: transform var(--transition-smooth), filter var(--transition-smooth);
}

.logo:hover .logo-icon,
.footer-logo:hover .logo-icon {
  transform: scale(1.08);
  filter: drop-shadow(0 0 10px rgba(124, 106, 255, 0.7));
}

.logo-icon svg {
  width: 100%;
  height: 100%;
  display: block;
}

.logo-accent {
  background: var(--accent-gradient-2);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.header-nav {
  display: flex;
  gap: 6px;
}

.nav-link {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  position: relative;
}

.nav-link:hover {
  color: var(--text-primary);
  background: rgba(124, 106, 255, 0.08);
}

.nav-link.active {
  color: var(--accent-primary);
}

/* ---------- Navigation Dropdown (19 Calculators) ---------- */
.nav-dropdown {
  position: relative;
  display: inline-block;
}

.nav-dropdown-btn {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.875rem;
  font-weight: 500;
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  gap: 6px;
  background: transparent;
  border: none;
  cursor: pointer;
  font-family: inherit;
}

.nav-dropdown-btn:hover,
.nav-dropdown:hover .nav-dropdown-btn {
  color: var(--text-primary);
  background: rgba(124, 106, 255, 0.08);
}

.nav-dropdown-btn .chevron {
  transition: transform var(--transition-fast);
}

.nav-dropdown:hover .nav-dropdown-btn .chevron {
  transform: rotate(180deg);
}

.nav-dropdown-menu {
  position: absolute;
  top: calc(100% + 4px);
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  width: 640px;
  max-width: 95vw;
  max-height: 480px;
  overflow-y: auto;
  background: var(--bg-card);
  border: 1.5px solid var(--border-card);
  border-radius: var(--radius-md);
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.6), 0 0 20px rgba(124, 106, 255, 0.15);
  padding: 16px;
  display: none;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
  z-index: 1000;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

.nav-dropdown:hover .nav-dropdown-menu,
.nav-dropdown:focus-within .nav-dropdown-menu {
  display: grid;
  animation: navDropIn 0.2s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

@keyframes navDropIn {
  from {
    opacity: 0;
    transform: translateX(-50%) translateY(4px);
  }

  to {
    opacity: 1;
    transform: translateX(-50%) translateY(8px);
  }
}

.nav-dropdown-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 8px 10px;
  border-radius: var(--radius-sm);
  text-decoration: none;
  color: var(--text-primary);
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid transparent;
  transition: all var(--transition-fast);
}

.nav-dropdown-item:hover {
  background: rgba(124, 106, 255, 0.1);
  border-color: rgba(124, 106, 255, 0.25);
  transform: translateX(2px);
}

.nav-dropdown-item-icon {
  font-size: 1.15rem;
  line-height: 1;
  flex-shrink: 0;
  margin-top: 2px;
}

.nav-dropdown-item-content {
  display: flex;
  flex-direction: column;
}

.nav-dropdown-item-title {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
  line-height: 1.25;
}

.nav-dropdown-item-desc {
  font-size: 0.72rem;
  color: var(--text-muted);
  line-height: 1.3;
  margin-top: 2px;
}

.theme-toggle {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-sm);
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--text-primary);
  border-color: var(--accent-primary);
  background: var(--glow-primary);
}

.theme-toggle svg {
  width: 18px;
  height: 18px;
}

.icon-moon {
  display: none;
}

[data-theme="light"] .icon-sun {
  display: none;
}

[data-theme="light"] .icon-moon {
  display: block;
}

/* ---------- Hero ---------- */
.hero {
  position: relative;
  z-index: 2;
  padding: 68px 20px 8px;
  text-align: center;
}

.hero-content {
  max-width: 900px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: 999px;
  padding: 3px 12px 3px 8px;
  font-size: 0.74rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
  backdrop-filter: blur(12px);
}

.badge-dot {
  width: 8px;
  height: 8px;
  background: #22c55e;
  border-radius: 50%;
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {

  0%,
  100% {
    opacity: 1;
    box-shadow: 0 0 0 0 rgba(34, 197, 94, 0.5);
  }

  50% {
    opacity: 0.8;
    box-shadow: 0 0 0 6px rgba(34, 197, 94, 0);
  }
}

.hero-title {
  font-size: clamp(1.7rem, 3.2vw, 2.4rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 6px;
}

.title-line {
  display: inline;
  margin: 0 4px;
}

.gradient-text {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  background-size: 200% 200%;
  animation: gradient-shift 6s ease-in-out infinite;
}

@keyframes gradient-shift {

  0%,
  100% {
    background-position: 0% 50%;
  }

  50% {
    background-position: 100% 50%;
  }
}

.hero-subtitle {
  font-size: 0.94rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 6px;
  line-height: 1.4;
}

.hero-cta {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 24px;
  background: var(--accent-gradient-2);
  color: #fff;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  border-radius: var(--radius-md);
  transition: all var(--transition-smooth);
  box-shadow: 0 4px 20px rgba(124, 106, 255, 0.35);
}

.hero-cta:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(124, 106, 255, 0.45);
}

.hero-cta svg {
  transition: transform var(--transition-fast);
}

.hero-cta:hover svg {
  transform: translateX(4px);
}

/* ---------- Calculator Section ---------- */
.calculator-section {
  position: relative;
  z-index: 2;
  padding: 4px 20px 50px;
}

.calculator-container {
  max-width: 1200px;
  margin: 0 auto;
}

.calc-header {
  text-align: center;
  margin-bottom: 12px;
}

.calc-title {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 2px;
}

.calc-desc {
  color: var(--text-secondary);
  font-size: 0.82rem;
  line-height: 1.35;
}

.calc-desc strong {
  color: var(--accent-primary);
  font-weight: 600;
}

/* ---------- Calculator Cards Grid ---------- */
.calc-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
  margin-bottom: 18px;
}

@media (max-width: 640px) {
  .header-inner {
    height: 50px;
    padding: 0 14px;
  }

  .hero {
    padding: 56px 12px 4px;
  }

  .hero-badge {
    margin-bottom: 4px;
    padding: 2px 8px;
    font-size: 0.68rem;
  }

  .hero-title {
    font-size: 1.45rem;
    margin-bottom: 4px;
  }

  .hero-subtitle {
    font-size: 0.82rem;
    line-height: 1.35;
    margin-bottom: 4px;
  }

  .calculator-section {
    padding: 2px 10px 36px;
  }

  .calc-header {
    margin-bottom: 8px;
  }

  .calc-title {
    font-size: 1.1rem;
    margin-bottom: 2px;
  }

  .calc-desc {
    font-size: 0.76rem;
  }

  .calc-grid {
    grid-template-columns: 1fr;
    gap: 8px;
    margin-bottom: 12px;
  }

  .calc-card {
    padding: 10px 12px;
    border-radius: 12px;
  }

  .card-icon-row {
    margin-bottom: 4px;
  }

  .card-icon {
    width: 26px;
    height: 26px;
  }

  .card-icon svg {
    width: 13px;
    height: 13px;
  }

  .card-label {
    font-size: 0.76rem;
    margin-bottom: 4px;
  }

  .calc-input {
    padding: 8px 10px;
    font-size: 0.95rem;
  }

  .unit-select {
    padding: 8px 24px 8px 8px;
    font-size: 0.76rem;
    min-width: 105px;
  }

  .card-converted {
    margin-top: 3px;
    font-size: 0.7rem;
    min-height: 15px;
  }
}

.calc-card {
  background: var(--bg-card);
  backdrop-filter: blur(24px) saturate(160%);
  -webkit-backdrop-filter: blur(24px) saturate(160%);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  transition: all var(--transition-smooth);
  position: relative;
  overflow: hidden;
}

.calc-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  opacity: 0;
  transition: opacity var(--transition-smooth);
  pointer-events: none;
}

.calc-card:hover {
  border-color: rgba(255, 255, 255, 0.1);
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}

/* Card accent borders on focus-within */
#voltage-card:focus-within,
#voltage-card.has-value {
  border-color: rgba(124, 106, 255, 0.3);
  box-shadow: 0 0 30px var(--voltage-glow), var(--shadow-card);
}

#current-card:focus-within,
#current-card.has-value {
  border-color: rgba(94, 231, 223, 0.3);
  box-shadow: 0 0 30px var(--current-glow), var(--shadow-card);
}

#resistance-card:focus-within,
#resistance-card.has-value {
  border-color: rgba(255, 140, 66, 0.3);
  box-shadow: 0 0 30px var(--resistance-glow), var(--shadow-card);
}

#power-card:focus-within,
#power-card.has-value {
  border-color: rgba(240, 107, 223, 0.3);
  box-shadow: 0 0 30px var(--power-glow), var(--shadow-card);
}

.card-icon-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 6px;
}

.card-icon {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-smooth);
}

.card-icon svg {
  width: 16px;
  height: 16px;
}

.voltage-icon {
  background: var(--voltage-glow);
  color: var(--voltage-color);
}

.current-icon {
  background: var(--current-glow);
  color: var(--current-color);
}

.resistance-icon {
  background: var(--resistance-glow);
  color: var(--resistance-color);
}

.power-icon {
  background: var(--power-glow);
  color: var(--power-color);
}

.card-badge {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 3px 10px;
  border-radius: 999px;
  background: rgba(124, 106, 255, 0.1);
  color: var(--accent-primary);
  opacity: 0;
  transform: scale(0.9);
  transition: all var(--transition-spring);
}

.card-badge.visible {
  opacity: 1;
  transform: scale(1);
}

.card-badge.user-input {
  background: rgba(34, 197, 94, 0.1);
  color: #22c55e;
}

.card-label {
  display: block;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
  letter-spacing: 0.01em;
}

.input-row {
  display: flex;
  gap: 8px;
  align-items: stretch;
}

.calc-input {
  flex: 1;
  background: var(--bg-input);
  border: 1px solid var(--border-input);
  border-radius: 10px;
  padding: 10px 14px;
  font-family: var(--font-mono);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  outline: none;
  transition: all var(--transition-fast);
  min-width: 0;
}

.calc-input::placeholder {
  color: var(--text-muted);
  font-family: var(--font-sans);
  font-weight: 500;
  font-size: 0.92rem;
  opacity: 0.9;
}

.calc-input:focus {
  background: var(--bg-input-focus);
  border-color: var(--border-input-focus);
  box-shadow: 0 0 0 3px var(--glow-primary);
}

.calc-input.computed {
  color: var(--accent-primary);
}

#voltage-card .calc-input.computed {
  color: var(--voltage-color);
}

#current-card .calc-input.computed {
  color: var(--current-color);
}

#resistance-card .calc-input.computed {
  color: var(--resistance-color);
}

#power-card .calc-input.computed {
  color: var(--power-color);
}

/* Remove number input spinners */
.calc-input::-webkit-inner-spin-button,
.calc-input::-webkit-outer-spin-button {
  -webkit-appearance: none;
  margin: 0;
}

.calc-input[type='number'] {
  -moz-appearance: textfield;
}

/* Unit Select */
.unit-select-wrap {
  position: relative;
  flex-shrink: 0;
}

.unit-select {
  appearance: none;
  -webkit-appearance: none;
  background: var(--bg-input);
  border: 1px solid var(--border-input);
  border-radius: 10px;
  padding: 10px 32px 10px 12px;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  outline: none;
  transition: all var(--transition-fast);
  min-width: 135px;
}

.unit-select option {
  background: #171728;
  color: #ffffff;
}

[data-theme="light"] .unit-select option {
  background: #ffffff;
  color: #0d0f18;
}

.unit-select:focus {
  border-color: var(--border-input-focus);
  box-shadow: 0 0 0 3px var(--glow-primary);
}

.unit-select:hover {
  border-color: rgba(255, 255, 255, 0.25);
}

.select-chevron {
  position: absolute;
  right: 12px;
  top: 50%;
  transform: translateY(-50%);
  width: 12px;
  height: 12px;
  color: var(--text-secondary);
  pointer-events: none;
}

/* Converted value display */
.card-converted {
  margin-top: 6px;
  font-size: 0.76rem;
  font-weight: 600;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  min-height: 18px;
  transition: all var(--transition-fast);
}

.card-converted.has-data {
  color: var(--text-primary);
}

/* ---------- Action Buttons ---------- */
.calc-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 32px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border: none;
  border-radius: var(--radius-md);
  font-family: var(--font-sans);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-smooth);
}

.btn-primary {
  background: var(--accent-gradient-2);
  color: #fff;
  box-shadow: 0 4px 16px rgba(124, 106, 255, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(124, 106, 255, 0.4);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border-card);
  backdrop-filter: blur(12px);
}

.btn-secondary:hover {
  color: var(--text-primary);
  border-color: rgba(255, 255, 255, 0.15);
  transform: translateY(-1px);
}

/* ---------- Formula Display ---------- */
.formula-display {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  text-align: center;
  backdrop-filter: blur(16px);
}

.formula-label {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.formula-text {
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.formula-text.active {
  color: var(--accent-primary);
}

/* ---------- Formulas Reference Section ---------- */
.formulas-section,
.how-section {
  position: relative;
  z-index: 2;
  padding: 80px 24px;
}

.section-container {
  max-width: 1200px;
  margin: 0 auto;
}

.section-title {
  text-align: center;
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  margin-bottom: 12px;
}

.section-subtitle {
  text-align: center;
  color: var(--text-secondary);
  font-size: 1rem;
  margin-bottom: 48px;
}

.formulas-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

@media (max-width: 768px) {
  .formulas-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .formulas-grid {
    grid-template-columns: 1fr;
  }
}

.formula-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 24px;
  backdrop-filter: blur(16px);
  transition: all var(--transition-smooth);
}

.formula-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card);
  border-color: rgba(255, 255, 255, 0.1);
}

.formula-card:nth-child(1):hover {
  border-color: rgba(124, 106, 255, 0.3);
}

.formula-card:nth-child(2):hover {
  border-color: rgba(94, 231, 223, 0.3);
}

.formula-card:nth-child(3):hover {
  border-color: rgba(255, 140, 66, 0.3);
}

.formula-card:nth-child(4):hover {
  border-color: rgba(240, 107, 223, 0.3);
}

.formula-card-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 18px;
}

.formula-symbol {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 700;
  flex-shrink: 0;
}

.formula-card:nth-child(1) .formula-symbol {
  background: var(--voltage-glow);
  color: var(--voltage-color);
}

.formula-card:nth-child(2) .formula-symbol {
  background: var(--current-glow);
  color: var(--current-color);
}

.formula-card:nth-child(3) .formula-symbol {
  background: var(--resistance-glow);
  color: var(--resistance-color);
}

.formula-card:nth-child(4) .formula-symbol {
  background: var(--power-glow);
  color: var(--power-color);
}

.formula-name {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-primary);
}

.formula-equations {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.formula-equations code {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--text-secondary);
  background: var(--bg-input);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-card);
}

/* ---------- How It Works ---------- */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

@media (max-width: 768px) {
  .steps-grid {
    grid-template-columns: 1fr;
  }
}

.step-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  backdrop-filter: blur(16px);
  transition: all var(--transition-smooth);
  text-align: center;
}

.step-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-card);
  border-color: rgba(255, 255, 255, 0.1);
}

.step-number {
  font-size: 2.5rem;
  font-weight: 800;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  margin-bottom: 16px;
  letter-spacing: -0.04em;
}

.step-title {
  font-size: 1.1rem;
  font-weight: 700;
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.step-desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ---------- Footer ---------- */
.site-footer {
  position: relative;
  z-index: 2;
  border-top: 1px solid var(--border-card);
  padding: 40px 24px;
  text-align: center;
}

.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
}

.footer-text {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.footer-copy {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ---------- Toast ---------- */
.toast {
  position: fixed;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%) translateY(100px);
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  backdrop-filter: blur(20px);
  color: var(--text-primary);
  padding: 14px 28px;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 500;
  z-index: 1000;
  opacity: 0;
  pointer-events: none;
  transition: all var(--transition-spring);
  box-shadow: var(--shadow-elevated);
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}

/* ---------- Scroll Animations ---------- */
.calc-card,
.formula-card,
.step-card {
  opacity: 0;
  transform: translateY(20px);
  animation: fadeInUp 0.6s ease-out forwards;
}

.calc-card:nth-child(1) {
  animation-delay: 0.05s;
}

.calc-card:nth-child(2) {
  animation-delay: 0.1s;
}

.calc-card:nth-child(3) {
  animation-delay: 0.15s;
}

.calc-card:nth-child(4) {
  animation-delay: 0.2s;
}

.formula-card:nth-child(1) {
  animation-delay: 0.05s;
}

.formula-card:nth-child(2) {
  animation-delay: 0.1s;
}

.formula-card:nth-child(3) {
  animation-delay: 0.15s;
}

.formula-card:nth-child(4) {
  animation-delay: 0.2s;
}

.step-card:nth-child(1) {
  animation-delay: 0.05s;
}

.step-card:nth-child(2) {
  animation-delay: 0.1s;
}

.step-card:nth-child(3) {
  animation-delay: 0.15s;
}

@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ---------- Responsive Mobile Nav ---------- */
@media (max-width: 768px) {
  .orb {
    opacity: 0.1 !important;
  }

  .site-header {
    background: rgba(9, 9, 15, 0.95);
  }

  [data-theme="light"] .site-header {
    background: rgba(246, 247, 251, 0.96);
  }
}

@media (max-width: 640px) {
  .header-nav {
    display: none;
  }

  .hero-title {
    font-size: 2rem;
  }

  .hero-subtitle {
    font-size: 0.95rem;
    line-height: 1.55;
    color: var(--text-secondary);
  }

  .calc-card {
    padding: 18px 16px;
    background: #141424;
    border-color: rgba(255, 255, 255, 0.16);
  }

  [data-theme="light"] .calc-card {
    background: #ffffff;
    border-color: rgba(0, 0, 0, 0.14);
  }

  .calc-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    justify-content: center;
    font-size: 1rem;
    padding: 14px 20px;
  }

  .section-title {
    font-size: 1.5rem;
  }

  .content-wrapper {
    padding: 24px 16px 60px;
  }

  .content-block h2 {
    font-size: 1.45rem;
  }

  .content-block h3 {
    font-size: 1.2rem;
  }

  .content-block p {
    font-size: 0.98rem;
    line-height: 1.7;
    color: var(--text-secondary);
  }

  .faq-question {
    padding: 16px 18px;
    font-size: 1rem;
  }

  .faq-answer {
    padding: 0 18px 16px;
    font-size: 0.95rem;
    line-height: 1.65;
    color: var(--text-secondary);
  }
}

@media (max-width: 480px) {
  .input-row {
    flex-direction: column;
    gap: 8px;
  }

  .unit-select {
    min-width: 100%;
    width: 100%;
  }

  .calc-card {
    padding: 16px 14px;
  }

  .hero-title {
    font-size: 1.75rem;
  }
}

/* ---------- Selection ---------- */
::selection {
  background: rgba(124, 106, 255, 0.3);
  color: var(--text-primary);
}

/* ---------- Focus visible ---------- */
:focus-visible {
  outline: 2px solid var(--accent-primary);
  outline-offset: 2px;
}

/* ---------- Scrollbar (Webkit) ---------- */
::-webkit-scrollbar {
  width: 8px;
}

::-webkit-scrollbar-track {
  background: var(--bg-primary);
}

::-webkit-scrollbar-thumb {
  background: var(--text-muted);
  border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-secondary);
}

/* ---------- RTL (Arabic & Right-to-Left) ---------- */
[dir="rtl"] {
  direction: rtl;
  text-align: right;
}

[dir="rtl"] .header-inner,
[dir="rtl"] .card-icon-row,
[dir="rtl"] .input-row,
[dir="rtl"] .calc-actions,
[dir="rtl"] .footer-inner {
  direction: rtl;
}

[dir="rtl"] .select-chevron {
  right: auto;
  left: 10px;
}

[dir="rtl"] .hero-badge .badge-dot {
  margin-right: 0;
  margin-left: 6px;
}

[dir="rtl"] .content-block h2::before {
  margin-left: 12px;
  margin-right: 0;
}

[dir="rtl"] .content-block ul li {
  padding-left: 0;
  padding-right: 26px;
}

[dir="rtl"] .content-block ul li::before {
  left: auto;
  right: 0;
}

[dir="rtl"] .formula-card-box .formula-code {
  border-left: none;
  border-right: 4px solid var(--accent-primary);
}

/* ---------- Rich Content & Article Sections ---------- */
.content-wrapper {
  max-width: 1040px;
  margin: 0 auto;
  padding: 40px 20px 80px;
  position: relative;
  z-index: 1;
}

.content-block {
  margin-bottom: 48px;
}

.content-block h2 {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 12px;
}

.content-block h2::before {
  content: '';
  display: inline-block;
  width: 4px;
  height: 1.2em;
  background: var(--accent-gradient);
  border-radius: 4px;
}

.content-block h3 {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 24px 0 12px;
  letter-spacing: -0.01em;
}

.content-block p {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.75;
  margin-bottom: 16px;
}

.content-block strong,
.styled-table strong,
.faq-answer strong,
.example-box strong,
.wheel-card strong {
  color: var(--text-primary);
  font-weight: 700;
}

.content-block ul {
  list-style: none;
  margin: 16px 0 24px;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.content-block ul li {
  position: relative;
  padding-left: 26px;
  color: var(--text-secondary);
  font-size: 1.02rem;
  line-height: 1.6;
}

.content-block ul li::before {
  content: '⚡';
  position: absolute;
  left: 0;
  top: 1px;
  font-size: 0.85rem;
  color: var(--accent-primary);
}

.formula-card-box {
  background: rgba(20, 20, 35, 0.7);
  border: 1px solid rgba(124, 106, 255, 0.25);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin: 20px 0;
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-card);
}

.formula-card-box .formula-title {
  font-size: 0.85rem;
  font-family: var(--font-mono);
  color: var(--accent-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 700;
  margin-bottom: 8px;
}

.formula-card-box .formula-code {
  font-family: var(--font-mono);
  font-size: 1.35rem;
  font-weight: 700;
  color: #fff;
  background: rgba(0, 0, 0, 0.35);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  border-left: 4px solid var(--accent-primary);
  display: inline-block;
  letter-spacing: 0.04em;
}

.example-box {
  background: linear-gradient(135deg, rgba(30, 25, 55, 0.6) 0%, rgba(15, 25, 45, 0.6) 100%);
  border: 1px solid rgba(94, 231, 223, 0.25);
  border-radius: var(--radius-md);
  padding: 24px;
  margin: 24px 0;
  box-shadow: 0 8px 30px rgba(0, 0, 0, 0.25);
}

.example-box .example-badge {
  display: inline-block;
  background: rgba(94, 231, 223, 0.15);
  color: var(--accent-secondary);
  border: 1px solid rgba(94, 231, 223, 0.35);
  font-size: 0.75rem;
  font-family: var(--font-mono);
  font-weight: 700;
  text-transform: uppercase;
  padding: 3px 10px;
  border-radius: 6px;
  margin-bottom: 12px;
}

.example-box .example-steps {
  font-family: var(--font-mono);
  font-size: 1.05rem;
  color: #e0e0f5;
  background: rgba(0, 0, 0, 0.4);
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  margin: 12px 0;
  line-height: 1.8;
}

.table-container {
  width: 100%;
  overflow-x: auto;
  margin: 24px 0;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-card);
  box-shadow: var(--shadow-card);
  background: var(--bg-card);
}

.styled-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.98rem;
}

.styled-table th {
  background: rgba(124, 106, 255, 0.15);
  color: var(--text-primary);
  font-weight: 700;
  padding: 14px 18px;
  border-bottom: 1px solid var(--border-card);
  font-family: var(--font-mono);
  font-size: 0.88rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.styled-table td {
  padding: 12px 18px;
  border-bottom: 1px solid var(--border-card);
  color: var(--text-secondary);
}

.styled-table tr:last-child td {
  border-bottom: none;
}

.styled-table tr:hover td {
  background: rgba(255, 255, 255, 0.03);
  color: var(--text-primary);
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
  margin-top: 20px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all var(--transition-smooth);
}

.faq-item:hover {
  border-color: rgba(124, 106, 255, 0.4);
  background: var(--bg-card-hover);
}

.faq-question {
  padding: 18px 22px;
  cursor: pointer;
  font-weight: 600;
  font-size: 1.08rem;
  color: var(--text-primary);
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
  list-style: none;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-icon {
  width: 20px;
  height: 20px;
  transition: transform var(--transition-fast);
  color: var(--accent-primary);
  flex-shrink: 0;
}

.faq-item[open] .faq-icon {
  transform: rotate(180deg);
}

.faq-answer {
  padding: 0 22px 20px;
  color: var(--text-secondary);
  font-size: 0.98rem;
  line-height: 1.7;
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  padding-top: 14px;
}

.tag-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.tag-item {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-card);
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 0.88rem;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all var(--transition-fast);
  font-weight: 500;
}

.tag-item:hover {
  background: rgba(124, 106, 255, 0.2);
  border-color: var(--accent-primary);
  color: #fff;
  transform: translateY(-2px);
}

/* ============================================================
   INTERACTIVE DIAGRAM COMPONENTS
   ============================================================ */

/* --- Shared Interactive Container --- */
.interactive-diagram {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 0;
  margin: 28px 0;
  backdrop-filter: blur(16px);
  overflow: hidden;
  transition: all var(--transition-smooth);
  opacity: 0;
  transform: translateY(20px);
}

.interactive-diagram.anim-visible {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}

.interactive-diagram:hover {
  border-color: rgba(124, 106, 255, 0.25);
  box-shadow: 0 8px 40px rgba(124, 106, 255, 0.08);
}

.diagram-header {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 20px;
  background: rgba(124, 106, 255, 0.06);
  border-bottom: 1px solid var(--border-card);
}

.diagram-badge {
  display: inline-block;
  background: rgba(94, 231, 223, 0.15);
  color: var(--accent-secondary);
  border: 1px solid rgba(94, 231, 223, 0.3);
  font-size: 0.68rem;
  font-family: var(--font-mono);
  font-weight: 700;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 6px;
  letter-spacing: 0.06em;
}

.diagram-title {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* --- Circuit Diagram --- */
.circuit-visual-area {
  padding: 24px;
  display: flex;
  justify-content: center;
}

.circuit-svg {
  width: 100%;
  max-width: 520px;
  height: auto;
}

.circuit-controls {
  display: flex;
  gap: 20px;
  padding: 0 24px 24px;
  flex-wrap: wrap;
}

.slider-group {
  flex: 1;
  min-width: 200px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.slider-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.styled-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.1);
  outline: none;
  cursor: pointer;
}

.styled-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--accent-primary);
  cursor: pointer;
  box-shadow: 0 2px 8px rgba(124, 106, 255, 0.4);
  transition: transform 0.15s ease;
}

.styled-slider::-webkit-slider-thumb:hover {
  transform: scale(1.2);
}

.styled-slider::-moz-range-thumb {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--accent-primary);
  cursor: pointer;
  border: none;
  box-shadow: 0 2px 8px rgba(124, 106, 255, 0.4);
}

.slider-value {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-primary);
  text-align: right;
}

/* --- Formula Wheel Grid --- */
.formula-wheel-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border-card);
}

.wheel-card {
  background: var(--bg-card);
  padding: 24px 20px;
  cursor: pointer;
  transition: all var(--transition-smooth);
  position: relative;
}

.wheel-card::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 0;
  height: 3px;
  background: var(--accent-primary);
  transition: width var(--transition-smooth);
  border-radius: 3px 3px 0 0;
}

.wheel-card.active::after,
.wheel-card:hover::after {
  width: 60%;
}

.wheel-card:hover {
  background: var(--bg-card-hover);
}

.wheel-card.active {
  background: rgba(124, 106, 255, 0.06);
}

.wheel-card-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 800;
  margin-bottom: 12px;
}

.wheel-card-formula {
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.wheel-card-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 0;
}

.wheel-card-detail {
  display: none;
  margin-top: 14px;
  padding-top: 14px;
  border-top: 1px solid var(--border-card);
}

.wheel-card.active .wheel-card-detail {
  display: block;
}

.wheel-card-detail p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.7;
}

.wheel-card-detail code {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  background: rgba(0, 0, 0, 0.3);
  padding: 4px 10px;
  border-radius: 6px;
  margin-top: 6px;
  color: var(--accent-secondary);
}

@media (max-width: 640px) {
  .formula-wheel-grid {
    grid-template-columns: 1fr;
  }
}

/* --- Ohm's Law Triangle --- */
.ohm-triangle-visual {
  display: flex;
  justify-content: center;
  padding: 24px;
}

.ohm-svg {
  width: 100%;
  max-width: 360px;
  height: auto;
}

.ohm-region {
  transition: fill var(--transition-fast);
}

.ohm-region:hover {
  cursor: pointer;
}

.ohm-result-box {
  padding: 18px 24px;
  background: rgba(124, 106, 255, 0.06);
  border-top: 1px solid var(--border-card);
  text-align: center;
}

.ohm-result-formula {
  font-family: var(--font-mono);
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--accent-primary);
  margin-bottom: 6px;
}

.ohm-result-desc {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

/* --- PVRC Relationship Grid --- */
.pvrc-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  padding: 20px;
}

.pvrc-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 20px;
  transition: all var(--transition-smooth);
  opacity: 0;
  transform: translateY(15px);
}

.pvrc-card.anim-visible {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.5s ease-out, transform 0.5s ease-out;
}

.pvrc-card:nth-child(1).anim-visible {
  transition-delay: 0.05s;
}

.pvrc-card:nth-child(2).anim-visible {
  transition-delay: 0.1s;
}

.pvrc-card:nth-child(3).anim-visible {
  transition-delay: 0.15s;
}

.pvrc-card:nth-child(4).anim-visible {
  transition-delay: 0.2s;
}

.pvrc-card:hover {
  border-color: rgba(124, 106, 255, 0.3);
  transform: translateY(-3px);
  box-shadow: var(--shadow-card);
}

.pvrc-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 12px;
}

.pvrc-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 0 0 4px;
}

.pvrc-unit {
  font-size: 0.8rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  margin: 0 0 10px;
}

.pvrc-def {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0 0 14px;
}

.pvrc-formulas {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.pvrc-formulas code {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  background: rgba(0, 0, 0, 0.3);
  padding: 4px 10px;
  border-radius: 6px;
  color: var(--accent-secondary);
  border: 1px solid rgba(94, 231, 223, 0.15);
}

@media (max-width: 640px) {
  .pvrc-grid {
    grid-template-columns: 1fr;
  }
}

/* --- Room Calculator --- */
.room-appliance-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  padding: 20px;
}

.room-appliance-card {
  background: rgba(20, 20, 35, 0.5);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 14px 12px;
  text-align: center;
  transition: all var(--transition-smooth);
  opacity: 0.6;
}

.room-appliance-card.active {
  opacity: 1;
  border-color: rgba(94, 231, 223, 0.3);
  background: rgba(94, 231, 223, 0.05);
}

.ra-icon {
  font-size: 1.6rem;
  margin-bottom: 6px;
}

.ra-name {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.ra-watts {
  font-size: 0.72rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  margin-bottom: 8px;
}

/* Toggle switch */
.ra-toggle {
  position: relative;
  display: inline-block;
  width: 36px;
  height: 20px;
  cursor: pointer;
}

.ra-toggle input {
  opacity: 0;
  width: 0;
  height: 0;
}

.ra-toggle-slider {
  position: absolute;
  inset: 0;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 20px;
  transition: background var(--transition-fast);
}

.ra-toggle-slider::before {
  content: '';
  position: absolute;
  width: 16px;
  height: 16px;
  left: 2px;
  bottom: 2px;
  background: var(--text-muted);
  border-radius: 50%;
  transition: all var(--transition-fast);
}

.ra-toggle input:checked+.ra-toggle-slider {
  background: rgba(94, 231, 223, 0.3);
}

.ra-toggle input:checked+.ra-toggle-slider::before {
  transform: translateX(16px);
  background: var(--accent-secondary);
}

.room-total-bar {
  padding: 16px 20px 20px;
  border-top: 1px solid var(--border-card);
}

.room-total-label {
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 4px;
}

.room-total-value {
  font-size: 1.6rem;
  font-family: var(--font-mono);
  font-weight: 800;
  color: var(--accent-secondary);
  margin-bottom: 10px;
}

.room-bar-track {
  width: 100%;
  height: 10px;
  background: rgba(255, 255, 255, 0.06);
  border-radius: 5px;
  overflow: hidden;
}

.room-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--accent-secondary), var(--voltage-color));
  border-radius: 5px;
  transition: width 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.room-bar-scale {
  display: flex;
  justify-content: space-between;
  font-size: 0.7rem;
  color: var(--text-muted);
  font-family: var(--font-mono);
  margin-top: 4px;
}

@media (max-width: 768px) {
  .room-appliance-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .room-appliance-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 8px;
  }
}

/* --- Appliance Bar Chart --- */
.appliance-bars {
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.bar-item {
  display: grid;
  grid-template-columns: 120px 1fr 90px;
  gap: 12px;
  align-items: center;
  opacity: 0;
  transform: translateX(-10px);
}

.bar-item.anim-visible {
  opacity: 1;
  transform: translateX(0);
  transition: opacity 0.4s ease-out, transform 0.4s ease-out;
}

.bar-item:nth-child(1).anim-visible {
  transition-delay: 0.05s;
}

.bar-item:nth-child(2).anim-visible {
  transition-delay: 0.1s;
}

.bar-item:nth-child(3).anim-visible {
  transition-delay: 0.15s;
}

.bar-item:nth-child(4).anim-visible {
  transition-delay: 0.2s;
}

.bar-item:nth-child(5).anim-visible {
  transition-delay: 0.25s;
}

.bar-item:nth-child(6).anim-visible {
  transition-delay: 0.3s;
}

.bar-item:nth-child(7).anim-visible {
  transition-delay: 0.35s;
}

.bar-item:nth-child(8).anim-visible {
  transition-delay: 0.4s;
}

.bar-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-primary);
  text-align: right;
}

.bar-track {
  width: 100%;
  height: 18px;
  background: rgba(255, 255, 255, 0.04);
  border-radius: 9px;
  overflow: hidden;
}

.bar-fill {
  height: 100%;
  border-radius: 9px;
  min-width: 4px;
  transition: width 0.8s cubic-bezier(0.4, 0, 0.2, 1);
}

.bar-value {
  font-size: 0.78rem;
  font-family: var(--font-mono);
  color: var(--text-muted);
  font-weight: 600;
}

.bar-item:hover .bar-fill {
  filter: brightness(1.3);
}

.bar-item:hover .bar-label {
  color: var(--accent-secondary);
}

@media (max-width: 480px) {
  .bar-item {
    grid-template-columns: 80px 1fr 70px;
    gap: 8px;
  }

  .bar-label {
    font-size: 0.72rem;
  }
}

/* --- Mini Calculator --- */
.mini-calc-body {
  padding: 24px;
}

.mini-calc-row {
  display: flex;
  align-items: flex-end;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

.mini-input-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 1;
  min-width: 100px;
  max-width: 160px;
}

.mini-input-group label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.mini-input-group input {
  background: var(--bg-input);
  border: 1px solid var(--border-input);
  border-radius: var(--radius-md);
  padding: 12px 14px;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--text-primary);
  outline: none;
  width: 100%;
  transition: all var(--transition-fast);
}

.mini-input-group input:focus {
  border-color: var(--border-input-focus);
  box-shadow: 0 0 0 3px var(--glow-primary);
}

.mini-input-group input::-webkit-inner-spin-button,
.mini-input-group input::-webkit-outer-spin-button {
  -webkit-appearance: none;
}

.mini-input-group input[type='number'] {
  -moz-appearance: textfield;
}

.mini-operator {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-muted);
  padding-bottom: 10px;
}

.mini-result-group {
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 1;
  min-width: 100px;
  max-width: 180px;
}

.mini-result-group label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.mini-result {
  background: rgba(240, 107, 223, 0.1);
  border: 2px solid var(--power-color);
  border-radius: var(--radius-md);
  padding: 11px 14px;
  font-family: var(--font-mono);
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--power-color);
  text-align: center;
}

/* --- Tabbed Examples --- */
.example-tab-buttons {
  display: flex;
  gap: 0;
  overflow-x: auto;
  border-bottom: 1px solid var(--border-card);
  scrollbar-width: none;
}

.example-tab-buttons::-webkit-scrollbar {
  display: none;
}

.etab-btn {
  background: none;
  border: none;
  padding: 12px 18px;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-muted);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--transition-fast);
  position: relative;
  border-bottom: 2px solid transparent;
}

.etab-btn:hover {
  color: var(--text-primary);
  background: rgba(124, 106, 255, 0.05);
}

.etab-btn.active {
  color: var(--accent-primary);
  border-bottom-color: var(--accent-primary);
}

.example-tab-content {
  padding: 20px;
}

.etab-panel {
  display: none;
}

.etab-panel.active {
  display: block;
  animation: fadeInTab 0.3s ease-out;
}

@keyframes fadeInTab {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* --- High-Contrast Enhancements for Mobile & Interactive Elements --- */
.etab-btn {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.etab-btn:hover {
  color: #ffffff;
}

.etab-btn.active {
  color: #ffffff;
  background: rgba(139, 122, 255, 0.18);
  border-bottom-color: var(--accent-primary);
}

.room-appliance-card {
  opacity: 0.88;
  border-color: rgba(255, 255, 255, 0.12);
}

.ra-watts {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.room-total-label {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.bar-label {
  color: var(--text-primary);
  font-weight: 700;
}

.bar-value {
  color: var(--text-secondary);
  font-weight: 700;
}

.slider-label {
  color: var(--text-primary);
  font-weight: 700;
}

.mini-input-group label,
.mini-result-group label {
  color: var(--text-secondary);
  font-weight: 700;
}

.mini-operator {
  color: var(--text-primary);
}

/* --- Language Pills Contrast --- */
#lang-bar-title {
  color: var(--accent-primary) !important;
  font-weight: 800 !important;
  font-size: 0.82rem !important;
  letter-spacing: 0.05em !important;
}

#lang-pills-container a {
  padding: 6px 12px !important;
  font-size: 0.82rem !important;
  font-weight: 600 !important;
  color: #ffffff !important;
  background: rgba(255, 255, 255, 0.1) !important;
  border: 1px solid rgba(255, 255, 255, 0.18) !important;
  text-decoration: none !important;
  border-radius: 8px !important;
  transition: all var(--transition-fast) !important;
}

#lang-pills-container a:hover {
  background: rgba(139, 122, 255, 0.3) !important;
  border-color: var(--accent-primary) !important;
  color: #ffffff !important;
  transform: translateY(-1px);
}

/* ============================================================
   SCREENSHOT-MATCHED 4-COLUMN FOOTER
   ============================================================ */
.site-footer {
  position: relative;
  z-index: 10;
  background: linear-gradient(180deg, #090a16 0%, #05060d 100%);
  border-top: 1px solid rgba(255, 255, 255, 0.08);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  margin-top: 80px;
  padding: 60px 0 28px;
  color: #94a3b8;
}

[data-theme="light"] .site-footer {
  background: linear-gradient(180deg, #f8fafc 0%, #f1f5f9 100%);
  border-top-color: rgba(0, 0, 0, 0.08);
  color: #64748b;
}

.footer-inner {
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 24px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.4fr 0.9fr 1.1fr 1.2fr;
  gap: 36px 32px;
  padding-bottom: 48px;
}

@media (max-width: 992px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 32px 24px;
  }
}

@media (max-width: 520px) {
  .footer-grid {
    grid-template-columns: 1fr;
    gap: 28px;
  }
}

.footer-col {
  display: flex;
  flex-direction: column;
}

.footer-col-title {
  font-size: 0.85rem;
  font-weight: 800;
  color: #ffffff;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 20px;
}

[data-theme="light"] .footer-col-title {
  color: #0f172a;
}

/* Brand Column */
.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.footer-logo {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 800;
  font-size: 1.35rem;
  color: #ffffff;
  letter-spacing: -0.02em;
}

[data-theme="light"] .footer-logo {
  color: #0f172a;
}

.footer-logo .logo-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  background: linear-gradient(135deg, rgba(0, 210, 255, 0.2), rgba(124, 106, 255, 0.25));
  border: 1px solid rgba(0, 210, 255, 0.4);
  border-radius: 10px;
  font-size: 1.15rem;
}

.footer-tagline {
  font-size: 0.9rem;
  color: #94a3b8;
  line-height: 1.6;
  max-width: 320px;
  margin: 0;
}

[data-theme="light"] .footer-tagline {
  color: #64748b;
}

/* Social icons */
.footer-socials {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 4px;
}

.social-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #94a3b8;
  text-decoration: none;
  transition: all 0.2s ease;
}

.social-btn.rounded-sq {
  border-radius: 8px;
}

.social-btn:hover {
  background: rgba(0, 210, 255, 0.15);
  border-color: rgba(0, 210, 255, 0.5);
  color: #00d2ff;
  transform: translateY(-2px);
}

[data-theme="light"] .social-btn {
  background: rgba(0, 0, 0, 0.04);
  border-color: rgba(0, 0, 0, 0.08);
  color: #64748b;
}

[data-theme="light"] .social-btn:hover {
  background: rgba(2, 132, 199, 0.12);
  border-color: #0284c7;
  color: #0284c7;
}

/* Links column */
.footer-links {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 13px;
}

.footer-links li a {
  color: #cbd5e1;
  text-decoration: none;
  font-size: 0.92rem;
  transition: all 0.2s ease;
  display: inline-block;
}

.footer-links li a:hover {
  color: #00d2ff;
  transform: translateX(3px);
}

[data-theme="light"] .footer-links li a {
  color: #475569;
}

[data-theme="light"] .footer-links li a:hover {
  color: #0284c7;
}

/* Contact column */
.footer-contact-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.footer-contact-item {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.92rem;
}

.footer-contact-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #00d2ff;
  flex-shrink: 0;
}

.footer-contact-item a {
  color: #cbd5e1;
  text-decoration: none;
  transition: color 0.2s ease;
}

.footer-contact-item a:hover {
  color: #00d2ff;
  text-decoration: underline;
}

[data-theme="light"] .footer-contact-item a {
  color: #334155;
}

[data-theme="light"] .footer-contact-item a:hover {
  color: #0284c7;
}

/* Language pills grid */
.footer-lang-grid {
  display: grid;
  grid-template-columns: repeat(5, 38px);
  gap: 8px;
}

@media (max-width: 380px) {
  .footer-lang-grid {
    grid-template-columns: repeat(4, 38px);
  }
}

.footer-lang-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 32px;
  border-radius: 8px;
  font-size: 0.72rem;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.2s ease;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #94a3b8;
  font-family: var(--font-sans);
  letter-spacing: 0.03em;
}

.footer-lang-pill:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.25);
  color: #ffffff;
  transform: translateY(-1px);
}

.footer-lang-pill.active {
  border: 1.5px solid #00d2ff;
  color: #00d2ff;
  background: rgba(0, 210, 255, 0.08);
  font-weight: 700;
  box-shadow: 0 0 10px rgba(0, 210, 255, 0.25);
}

[data-theme="light"] .footer-lang-pill {
  background: rgba(0, 0, 0, 0.03);
  border-color: rgba(0, 0, 0, 0.08);
  color: #64748b;
}

[data-theme="light"] .footer-lang-pill:hover {
  background: rgba(0, 0, 0, 0.07);
  color: #0f172a;
}

[data-theme="light"] .footer-lang-pill.active {
  border-color: #0284c7;
  color: #0284c7;
  background: rgba(2, 132, 199, 0.1);
}

/* Footer bottom bar */
.footer-bottom {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  padding-top: 24px;
}

.footer-copy {
  margin: 0;
  font-size: 0.88rem;
  color: #64748b;
  text-align: center;
}

[data-theme="light"] .footer-copy {
  color: #94a3b8;
}

.footer-back-to-top {
  position: absolute;
  right: 0;
  bottom: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border-radius: 8px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: #00d2ff;
  text-decoration: none;
  transition: all 0.2s ease;
}

.footer-back-to-top:hover {
  background: rgba(0, 210, 255, 0.15);
  border-color: rgba(0, 210, 255, 0.5);
  transform: translateY(-2px);
}

[data-theme="light"] .footer-back-to-top {
  background: rgba(0, 0, 0, 0.04);
  border-color: rgba(0, 0, 0, 0.08);
  color: #0284c7;
}

/* ============================================================
   COMPANY & LEGAL PAGES (About, Contact, Privacy, Terms)
   ============================================================ */
.page-container {
  max-width: 1080px;
  margin: 0 auto;
  padding: 40px 24px 80px;
  position: relative;
  z-index: 1;
}

.page-header-banner {
  text-align: center;
  max-width: 780px;
  margin: 20px auto 48px;
}

.page-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: 24px;
  background: rgba(139, 122, 255, 0.12);
  border: 1px solid rgba(139, 122, 255, 0.3);
  font-size: 0.82rem;
  font-family: var(--font-mono);
  color: var(--accent-primary);
  font-weight: 600;
  margin-bottom: 16px;
}

.page-title {
  font-size: 2.75rem;
  font-weight: 900;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  line-height: 1.15;
  margin-bottom: 18px;
}

@media (max-width: 640px) {
  .page-title {
    font-size: 2rem;
  }
}

.page-lead {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.breadcrumbs a {
  color: var(--accent-primary);
  text-decoration: none;
}

.breadcrumbs a:hover {
  text-decoration: underline;
}

.glass-card {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  padding: 36px;
  box-shadow: var(--shadow-card);
  margin-bottom: 28px;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
}

@media (max-width: 640px) {
  .glass-card {
    padding: 24px 18px;
  }
}

.glass-card h2 {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 16px;
  letter-spacing: -0.01em;
  display: flex;
  align-items: center;
  gap: 12px;
}

.glass-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  margin: 24px 0 10px;
}

.glass-card p {
  color: var(--text-secondary);
  line-height: 1.7;
  font-size: 0.98rem;
  margin-bottom: 16px;
}

.glass-card p:last-child {
  margin-bottom: 0;
}

.glass-card ul,
.glass-card ol {
  color: var(--text-secondary);
  margin: 12px 0 20px 24px;
  line-height: 1.7;
  font-size: 0.96rem;
}

.glass-card li {
  margin-bottom: 8px;
}

.glass-card li strong {
  color: var(--text-primary);
}

/* Stats Counter Grid */
.company-stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 18px;
  margin: 32px 0 40px;
}

@media (max-width: 800px) {
  .company-stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 480px) {
  .company-stats-grid {
    grid-template-columns: 1fr;
  }
}

.stat-card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 22px 18px;
  text-align: center;
  transition: transform var(--transition-fast), border-color var(--transition-fast);
}

.stat-card:hover {
  transform: translateY(-2px);
  border-color: var(--accent-primary);
}

.stat-number {
  font-size: 2.2rem;
  font-weight: 900;
  font-family: var(--font-mono);
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  margin-bottom: 6px;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 600;
}

/* Standards Pills Grid */
.standards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 16px;
  margin: 20px 0;
}

.standard-card {
  padding: 20px;
  border-radius: var(--radius-md);
  background: rgba(139, 122, 255, 0.06);
  border: 1px solid rgba(139, 122, 255, 0.2);
}

.standard-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 8px;
}

.standard-code {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--accent-secondary);
}

.standard-badge {
  font-size: 0.72rem;
  font-family: var(--font-mono);
  padding: 3px 8px;
  border-radius: 6px;
  background: rgba(94, 231, 223, 0.15);
  color: var(--accent-secondary);
}

.standard-card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.55;
}

/* Contact Page Layout */
.contact-layout {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 32px;
}

@media (max-width: 860px) {
  .contact-layout {
    grid-template-columns: 1fr;
  }
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

@media (max-width: 560px) {
  .form-row {
    grid-template-columns: 1fr;
  }
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.form-group label {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-primary);
}

.form-group input,
.form-group select,
.form-group textarea {
  background: var(--bg-input);
  border: 1px solid var(--border-input);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  outline: none;
  transition: all var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
  background: var(--bg-input-focus);
  border-color: var(--border-input-focus);
  box-shadow: 0 0 0 3px rgba(139, 122, 255, 0.18);
}

.form-group textarea {
  min-height: 140px;
  resize: vertical;
}

.contact-submit-btn {
  background: linear-gradient(135deg, #8b7aff 0%, #7c6aff 100%);
  color: #ffffff;
  border: none;
  border-radius: var(--radius-md);
  padding: 14px 28px;
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  box-shadow: 0 4px 18px rgba(139, 122, 255, 0.35);
  transition: all var(--transition-fast);
}

.contact-submit-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(139, 122, 255, 0.5);
}

.contact-channels {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.channel-card {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 20px;
  display: flex;
  align-items: flex-start;
  gap: 16px;
}

.channel-icon {
  width: 42px;
  height: 42px;
  border-radius: 10px;
  background: rgba(139, 122, 255, 0.12);
  border: 1px solid rgba(139, 122, 255, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  flex-shrink: 0;
}

.channel-info h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 4px;
}

.channel-info p {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 6px;
  line-height: 1.4;
}

.channel-info a {
  font-size: 0.85rem;
  font-family: var(--font-mono);
  color: var(--accent-secondary);
  text-decoration: none;
  font-weight: 600;
}

.channel-info a:hover {
  text-decoration: underline;
}

/* Legal Clause Callout */
.legal-callout {
  border-left: 4px solid var(--accent-warning);
  background: rgba(255, 160, 92, 0.08);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 18px 20px;
  margin: 20px 0;
}

.legal-callout-title {
  font-weight: 800;
  color: var(--accent-warning);
  font-size: 0.92rem;
  margin-bottom: 6px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.legal-callout p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin: 0;
}

/* ============================================================
   Specialized Calculators Hub Section (Homepage)
   ============================================================ */
.tools-hub-section {
  position: relative;
}

.tools-hub-header {
  margin-bottom: 24px;
}

.tools-hub-subtitle {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.6;
  max-width: 800px;
  margin-top: 8px;
}

.tools-filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 28px;
}

.tool-filter-btn {
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  color: var(--text-secondary);
  padding: 8px 16px;
  border-radius: 999px;
  font-size: 0.88rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.25s ease;
  font-family: var(--font-sans);
}

.tool-filter-btn:hover {
  border-color: var(--accent-primary);
  color: var(--text-primary);
  background: rgba(124, 106, 255, 0.08);
}

.tool-filter-btn.active {
  background: var(--accent-primary);
  color: #fff;
  border-color: var(--accent-primary);
  box-shadow: 0 4px 15px rgba(124, 106, 255, 0.35);
}

.tool-hub-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(310px, 1fr));
  gap: 20px;
}

.tool-hub-card {
  background: var(--bg-card);
  border: 1.5px solid var(--border-card);
  border-radius: 16px;
  padding: 22px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  text-decoration: none;
  color: var(--text-primary);
  transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
  position: relative;
  overflow: hidden;
}

.tool-hub-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--card-accent, var(--accent-primary));
  opacity: 0.8;
  transition: height 0.25s ease;
}

.tool-hub-card:hover {
  transform: translateY(-5px);
  border-color: var(--card-accent, var(--accent-primary));
  box-shadow: 0 12px 30px rgba(0, 0, 0, 0.25), 0 0 20px rgba(124, 106, 255, 0.12);
}

.tool-hub-card:hover::before {
  height: 5px;
}

.tool-card-top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.tool-card-icon {
  width: 44px;
  height: 44px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-card);
  flex-shrink: 0;
}

.tool-card-category {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-muted);
}

.tool-card-title {
  font-size: 1.12rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
  line-height: 1.35;
}

.tool-card-desc {
  font-size: 0.86rem;
  color: var(--text-secondary);
  line-height: 1.5;
  margin-bottom: 16px;
  flex-grow: 1;
}

.tool-io-block {
  background: var(--bg-input);
  border-radius: 10px;
  padding: 10px 12px;
  margin-bottom: 16px;
  border: 1px solid var(--border-input);
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.78rem;
}

.tool-io-row {
  display: flex;
  align-items: baseline;
  gap: 6px;
}

.tool-io-label {
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  font-size: 0.7rem;
  padding: 2px 6px;
  border-radius: 4px;
  flex-shrink: 0;
}

.tool-io-label.input-tag {
  background: rgba(124, 106, 255, 0.18);
  color: var(--accent-primary);
}

.tool-io-label.output-tag {
  background: rgba(46, 204, 113, 0.18);
  color: #2ecc71;
}

.tool-io-values {
  color: var(--text-secondary);
  font-family: var(--font-mono);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.tool-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--border-card);
  padding-top: 12px;
  margin-top: 4px;
}

.tool-card-action {
  font-size: 0.86rem;
  font-weight: 700;
  color: var(--card-accent, var(--accent-primary));
  display: flex;
  align-items: center;
  gap: 6px;
  transition: gap 0.2s ease;
}

.tool-hub-card:hover .tool-card-action {
  gap: 10px;
}

.tool-hub-card.hidden {
  display: none !important;
}

/* ============================================================
   Interactive Heading Visuals & Diagram Cards (All Subpages)
   ============================================================ */
.interactive-heading-card {
  background: linear-gradient(145deg, rgba(26, 34, 52, 0.75), rgba(15, 23, 42, 0.85));
  border: 1.5px solid rgba(255, 255, 255, 0.08);
  border-radius: 16px;
  padding: 22px;
  margin: 20px 0;
  position: relative;
  overflow: hidden;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.25);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
}

.interactive-heading-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--tool-accent, var(--accent-primary)), transparent);
  opacity: 0.8;
}

.heading-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 8px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  padding-bottom: 10px;
}

.heading-card-title {
  font-size: 0.96rem;
  font-weight: 700;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 8px;
}

.heading-card-badge {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  padding: 3px 8px;
  border-radius: 6px;
  background: rgba(124, 106, 255, 0.15);
  color: var(--accent-primary);
  border: 1px solid rgba(124, 106, 255, 0.25);
}

.heading-ctrl-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 14px;
}

.heading-ctrl-btn {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  color: var(--text-secondary);
  padding: 6px 14px;
  border-radius: 999px;
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: var(--font-sans);
}

.heading-ctrl-btn:hover {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
  border-color: var(--tool-accent, var(--accent-primary));
}

.heading-ctrl-btn.active {
  background: var(--tool-accent, var(--accent-primary));
  color: #fff;
  border-color: var(--tool-accent, var(--accent-primary));
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
}

.heading-display-box {
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.06);
  border-radius: 12px;
  padding: 16px;
  margin-top: 12px;
}

.heading-metric-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(130px, 1fr));
  gap: 12px;
  margin-top: 10px;
}

.heading-metric-item {
  background: rgba(255, 255, 255, 0.03);
  border-radius: 8px;
  padding: 10px 12px;
  border: 1px solid rgba(255, 255, 255, 0.04);
}

.heading-metric-label {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 4px;
}

.heading-metric-val {
  font-size: 1.15rem;
  font-weight: 800;
  font-family: var(--font-mono);
  color: var(--text-primary);
}

.heading-metric-val.accent {
  color: var(--tool-accent, var(--accent-primary));
}

.heading-slider-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin: 12px 0;
}

.heading-slider-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.heading-slider {
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: rgba(255, 255, 255, 0.1);
  outline: none;
  cursor: pointer;
  accent-color: var(--tool-accent, var(--accent-primary));
}

.glow-preview-box {
  width: 100%;
  height: 60px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.9rem;
  font-weight: 700;
  color: #111;
  transition: all 0.3s ease;
  margin: 10px 0;
}