/* ==========================================================================
   OZ TO LITERS — Design System & Styles
   A premium, SaaS-quality design system for the Oz to Liters Converter.
   ========================================================================== */

/* ---------- Google Fonts (Poppins) ---------- */
@import url('https://fonts.googleapis.com/css2?family=Poppins:wght@300;400;500;600;700&display=swap');

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Colors — Primary */
  --color-primary: #2563EB;
  --color-primary-hover: #1D4ED8;
  --color-primary-light: #DBEAFE;
  --color-primary-50: #EFF6FF;
  --color-primary-100: #DBEAFE;
  --color-primary-600: #2563EB;
  --color-primary-700: #1D4ED8;

  /* Colors — Secondary */
  --color-secondary: #7C3AED;
  --color-secondary-hover: #6D28D9;
  --color-secondary-light: #EDE9FE;
  --color-secondary-50: #F5F3FF;

  /* Colors — Accent Gradient */
  --gradient-primary: linear-gradient(135deg, #2563EB 0%, #7C3AED 100%);
  --gradient-primary-soft: linear-gradient(135deg, #EFF6FF 0%, #F5F3FF 100%);
  --gradient-hero-border: linear-gradient(135deg, #2563EB 0%, #7C3AED 50%, #2563EB 100%);

  /* Colors — Neutrals */
  --color-bg: #FFFFFF;
  --color-bg-alt: #F8FAFC;
  --color-bg-subtle: #F1F5F9;
  --color-surface: #FFFFFF;
  --color-text: #0F172A;
  --color-text-secondary: #334155;
  --color-text-muted: #64748B;
  --color-text-light: #94A3B8;
  --color-border: #E2E8F0;
  --color-border-light: #F1F5F9;

  /* Colors — Semantic */
  --color-success: #10B981;
  --color-info: #3B82F6;

  /* Shadows */
  --shadow-xs: 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06), 0 1px 2px rgba(15, 23, 42, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(15, 23, 42, 0.06), 0 2px 4px -2px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(15, 23, 42, 0.06), 0 4px 6px -4px rgba(15, 23, 42, 0.04);
  --shadow-xl: 0 20px 25px -5px rgba(15, 23, 42, 0.07), 0 8px 10px -6px rgba(15, 23, 42, 0.04);
  --shadow-2xl: 0 25px 50px -12px rgba(15, 23, 42, 0.15);
  --shadow-converter: 0 20px 60px -10px rgba(37, 99, 235, 0.12), 0 8px 20px -6px rgba(124, 58, 237, 0.08);
  --shadow-card-hover: 0 12px 24px -4px rgba(15, 23, 42, 0.08), 0 4px 8px -2px rgba(15, 23, 42, 0.04);

  /* Spacing — 8px scale */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  --space-20: 80px;
  --space-24: 96px;
  --space-32: 128px;

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-xl: 20px;
  --radius-2xl: 24px;
  --radius-full: 9999px;

  /* Typography */
  --font-family: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-size-xs: 0.8125rem;
  --font-size-sm: 0.9375rem;
  --font-size-base: 1.0625rem;
  --font-size-lg: 1.1875rem;
  --font-size-xl: 1.3125rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;

  /* Line Heights */
  --leading-tight: 1.2;
  --leading-snug: 1.35;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
  --transition-slow: 400ms ease;
  --transition-spring: 500ms cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Layout */
  --container-max: 1200px;
  --container-narrow: 800px;
  --nav-height: 72px;
}


/* ==========================================================================
   Reset & Base
   ========================================================================== */

*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-height);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  font-weight: 400;
  line-height: var(--leading-normal);
  color: var(--color-text);
  background-color: var(--color-bg);
  overflow-x: hidden;
}

img, svg {
  display: block;
  max-width: 100%;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--color-primary-hover);
}

button {
  font-family: inherit;
  cursor: pointer;
  border: none;
  background: none;
}

input {
  font-family: inherit;
  border: none;
  outline: none;
}

ul, ol {
  list-style: none;
}


/* ==========================================================================
   Layout Utilities
   ========================================================================== */

.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.container--narrow {
  max-width: var(--container-narrow);
}

.section {
  padding: var(--space-24) 0;
}

.section--alt {
  background-color: var(--color-bg-alt);
}

.section__header {
  text-align: center;
  max-width: 640px;
  margin: 0 auto var(--space-16);
}

.section__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-4);
  background: var(--gradient-primary-soft);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-4);
}

.section__badge svg {
  width: 14px;
  height: 14px;
}

.section__title {
  font-size: var(--font-size-4xl);
  font-weight: 600;
  line-height: var(--leading-tight);
  color: var(--color-text);
  margin-bottom: var(--space-4);
}

.section__subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  line-height: var(--leading-relaxed);
}


/* ==========================================================================
   Typography
   ========================================================================== */

h1 { font-weight: 700; line-height: var(--leading-tight); }
h2 { font-weight: 600; line-height: var(--leading-tight); }
h3 { font-weight: 500; line-height: var(--leading-snug); }

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


/* ==========================================================================
   Navigation
   ========================================================================== */

.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-height);
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color var(--transition-base), box-shadow var(--transition-base);
}

.nav--scrolled {
  border-bottom-color: var(--color-border);
  box-shadow: var(--shadow-sm);
}

.nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--space-6);
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-text);
  text-decoration: none;
}

.nav__logo-icon {
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
  font-size: var(--font-size-sm);
}

.nav__links {
  display: flex;
  align-items: center;
  gap: var(--space-8);
}

.nav__link {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  text-decoration: none;
  transition: color var(--transition-fast);
  position: relative;
}

.nav__link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--gradient-primary);
  border-radius: 1px;
  transition: width var(--transition-base);
}

.nav__link:hover {
  color: var(--color-primary);
}

.nav__link:hover::after {
  width: 100%;
}

.nav__cta {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-5);
  background: var(--gradient-primary);
  color: #fff;
  font-size: var(--font-size-sm);
  font-weight: 500;
  border-radius: var(--radius-full);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast);
}

.nav__cta:hover {
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(37, 99, 235, 0.3);
}

.nav__mobile-toggle {
  display: none;
  width: 40px;
  height: 40px;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--color-text);
  transition: background var(--transition-fast);
}

.nav__mobile-toggle:hover {
  background: var(--color-bg-subtle);
}

.nav__mobile-toggle svg {
  width: 24px;
  height: 24px;
}


/* ==========================================================================
   Hero Section
   ========================================================================== */

.hero {
  padding-top: calc(var(--nav-height) + var(--space-16));
  padding-bottom: var(--space-20);
  background: linear-gradient(180deg, var(--color-bg-alt) 0%, var(--color-bg) 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -200px;
  right: -200px;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(37, 99, 235, 0.04) 0%, transparent 70%);
  pointer-events: none;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -150px;
  left: -150px;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(124, 58, 237, 0.03) 0%, transparent 70%);
  pointer-events: none;
}

.hero__content {
  text-align: center;
  max-width: 700px;
  margin: 0 auto var(--space-12);
  position: relative;
  z-index: 1;
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-4);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-primary);
  margin-bottom: var(--space-6);
  box-shadow: var(--shadow-xs);
}

.hero__badge-dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-success);
  animation: pulse-dot 2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(1.3); }
}

.hero__title {
  font-size: var(--font-size-5xl);
  font-weight: 700;
  line-height: var(--leading-tight);
  margin-bottom: var(--space-5);
  letter-spacing: 0;
  overflow-wrap: break-word;
}

.hero__subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  line-height: var(--leading-relaxed);
  max-width: 560px;
  margin: 0 auto;
}


/* ==========================================================================
   Converter Widget — The Hero Product
   ========================================================================== */

.converter {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 680px;
  margin: 0 auto;
}

.converter__card {
  background: var(--color-surface);
  border-radius: var(--radius-xl);
  padding: var(--space-10);
  box-shadow: var(--shadow-converter);
  border: 1px solid var(--color-border);
  position: relative;
  overflow: hidden;
}

.converter__card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-primary);
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
}

.converter__fields {
  display: flex;
  align-items: stretch;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
  min-width: 0;
}

.converter__field {
  flex: 1;
  min-width: 0;
  position: relative;
}

.converter__label {
  display: block;
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-2);
}

.converter__input-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

.converter__input {
  width: 100%;
  padding: var(--space-4) var(--space-4);
  padding-right: 60px;
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--color-text);
  background: var(--color-bg-alt);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.converter__input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
  background: var(--color-bg);
}

.converter__input::placeholder {
  color: var(--color-text-light);
  font-weight: 400;
}

.converter__unit {
  position: absolute;
  right: var(--space-4);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  pointer-events: none;
}

.converter__swap {
  display: flex;
  align-items: center;
  justify-content: center;
  align-self: flex-end;
  width: 48px;
  height: 48px;
  margin-bottom: 0;
  border-radius: var(--radius-full);
  background: var(--gradient-primary-soft);
  border: 1px solid var(--color-border);
  color: var(--color-primary);
  flex-shrink: 0;
  transition: transform var(--transition-base), box-shadow var(--transition-fast);
  cursor: pointer;
}

.converter__swap:hover {
  transform: rotate(180deg);
  box-shadow: var(--shadow-md);
}

.converter__swap svg {
  width: 20px;
  height: 20px;
}

.converter__result-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-4) var(--space-5);
  background: var(--gradient-primary-soft);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-6);
  min-width: 0;
}

.converter__formula {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  min-width: 0;
  overflow-wrap: anywhere;
}

.converter__formula strong {
  color: var(--color-primary);
  font-weight: 600;
}

.converter__copy-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-3);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-primary);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  flex-shrink: 0;
}

.converter__copy-btn:hover {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

.converter__copy-btn svg {
  width: 14px;
  height: 14px;
}

.converter__actions {
  display: flex;
  gap: var(--space-3);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-size-sm);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
}

.btn--primary {
  flex: 1;
  background: var(--gradient-primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.2);
}

.btn--primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(37, 99, 235, 0.3);
}

.btn--secondary {
  flex: 1;
  background: var(--color-bg);
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
}

.btn--secondary:hover {
  background: var(--color-bg-alt);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn svg {
  width: 16px;
  height: 16px;
}


/* ---------- Trust Badges ---------- */

.trust-badges {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-8);
  margin-top: var(--space-10);
  flex-wrap: wrap;
}

.trust-badge {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

.trust-badge__icon {
  width: 20px;
  height: 20px;
  color: var(--color-success);
  flex-shrink: 0;
}


/* ==========================================================================
   Homepage Feature Sections
   ========================================================================== */

.how-it-works__grid,
.containers__grid,
.info-cards__grid,
.related-converters__grid {
  display: grid;
  gap: var(--space-6);
}

.how-it-works__grid {
  grid-template-columns: repeat(3, 1fr);
}

.step-card {
  position: relative;
  min-height: 260px;
  padding: var(--space-8);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
}

.step-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-card-hover);
}

.step-card__number {
  position: absolute;
  top: var(--space-5);
  right: var(--space-5);
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-full);
  background: var(--color-bg-subtle);
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  font-weight: 700;
}

.step-card__icon {
  width: 44px;
  height: 44px;
  padding: var(--space-2);
  margin-bottom: var(--space-6);
  border-radius: var(--radius-md);
  background: var(--gradient-primary-soft);
  color: var(--color-primary);
}

.step-card__title {
  margin-bottom: var(--space-3);
  font-size: var(--font-size-xl);
  color: var(--color-text);
}

.step-card__desc {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  line-height: var(--leading-relaxed);
}

.visual-converter {
  display: grid;
  grid-template-columns: minmax(260px, 0.85fr) 1.15fr;
  gap: var(--space-12);
  align-items: center;
  max-width: 920px;
  margin: 0 auto;
  padding: var(--space-8);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.measuring-cup {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-4);
}

.measuring-cup__container {
  width: min(100%, 280px);
  aspect-ratio: 5 / 7;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
}

.measuring-cup__svg {
  width: 100%;
  height: 100%;
}

.measuring-cup__value {
  display: inline-flex;
  align-items: baseline;
  gap: var(--space-1);
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-full);
  background: var(--color-primary-50);
  color: var(--color-primary);
  font-weight: 700;
}

.scale-panel {
  min-width: 0;
}

.scale-panel__title {
  margin-bottom: var(--space-3);
  font-size: var(--font-size-2xl);
  color: var(--color-text);
}

.scale-panel__desc {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  line-height: var(--leading-relaxed);
  margin-bottom: var(--space-6);
}

.scale-input {
  position: relative;
  max-width: 260px;
  margin-bottom: var(--space-5);
}

.scale-input__field {
  width: 100%;
  padding: var(--space-3) var(--space-12) var(--space-3) var(--space-4);
  background: var(--color-bg-alt);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-md);
  color: var(--color-text);
  font-size: var(--font-size-xl);
  font-weight: 600;
}

.scale-input__field:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.scale-input__unit {
  position: absolute;
  top: 50%;
  right: var(--space-4);
  transform: translateY(-50%);
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  font-weight: 600;
  pointer-events: none;
}

.scale-bar {
  height: 14px;
  overflow: hidden;
  border-radius: var(--radius-full);
  background: var(--color-bg-subtle);
  border: 1px solid var(--color-border);
}

.scale-bar__fill {
  height: 100%;
  border-radius: inherit;
  background: var(--gradient-primary);
  transition: width var(--transition-base);
}

.scale-bar__labels {
  display: flex;
  justify-content: space-between;
  gap: var(--space-2);
  margin-top: var(--space-2);
  color: var(--color-text-muted);
  font-size: var(--font-size-xs);
}

.scale-result {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  margin-top: var(--space-6);
}

.scale-result__value {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  color: var(--color-primary);
}

.scale-result__unit {
  color: var(--color-text-muted);
  font-weight: 500;
}

.containers__grid {
  grid-template-columns: repeat(5, 1fr);
}

.container-card {
  min-height: 210px;
  padding: var(--space-6) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  text-align: center;
  cursor: pointer;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
}

.container-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-card-hover);
}

.container-card__icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto var(--space-4);
  padding: var(--space-2);
  border-radius: var(--radius-md);
  background: var(--gradient-primary-soft);
  color: var(--color-primary);
}

.container-card__name {
  font-weight: 600;
  color: var(--color-text);
}

.container-card__oz {
  margin-top: var(--space-2);
  color: var(--color-primary);
  font-size: var(--font-size-xl);
  font-weight: 700;
}

.container-card__liters {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
}

.container-card__action {
  margin-top: var(--space-4);
  color: var(--color-primary);
  font-size: var(--font-size-xs);
  font-weight: 600;
}

.info-cards__grid {
  grid-template-columns: repeat(2, 1fr);
  max-width: 960px;
  margin: 0 auto;
}

.info-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.info-card.is-open {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-md);
}

.info-card__header {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: var(--space-4);
  min-height: 96px;
  padding: var(--space-5);
  cursor: pointer;
}

.info-card__icon,
.info-card__toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.info-card__icon {
  width: 44px;
  height: 44px;
  padding: var(--space-2);
  border-radius: var(--radius-md);
  background: var(--gradient-primary-soft);
  color: var(--color-primary);
}

.info-card__title {
  color: var(--color-text);
  font-size: var(--font-size-base);
  font-weight: 600;
}

.info-card__teaser {
  margin-top: 2px;
  color: var(--color-text-muted);
  font-size: var(--font-size-xs);
}

.info-card__toggle {
  width: 28px;
  height: 28px;
  color: var(--color-text-muted);
  transition: transform var(--transition-base), color var(--transition-fast);
}

.info-card.is-open .info-card__toggle {
  transform: rotate(180deg);
  color: var(--color-primary);
}

.info-card__body {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
}

.info-card__body-inner {
  padding: 0 var(--space-5) var(--space-5);
  color: var(--color-text-secondary);
  font-size: var(--font-size-sm);
  line-height: var(--leading-relaxed);
}

.info-card__body-inner p + p {
  margin-top: var(--space-3);
}

.related-converters__grid {
  grid-template-columns: repeat(3, 1fr);
}

.related-card {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: var(--space-4);
  min-height: 120px;
  padding: var(--space-5);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), border-color var(--transition-fast);
}

.related-card:hover {
  transform: translateY(-3px);
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-card-hover);
  color: var(--color-text);
}

.related-card__icon {
  width: 44px;
  height: 44px;
  padding: var(--space-2);
  border-radius: var(--radius-md);
  background: var(--gradient-primary-soft);
  color: var(--color-primary);
}

.related-card__name {
  font-weight: 600;
}

.related-card__desc {
  margin-top: 2px;
  color: var(--color-text-muted);
  font-size: var(--font-size-xs);
}

.related-card__arrow {
  width: 20px;
  height: 20px;
  color: var(--color-text-light);
  transition: transform var(--transition-fast), color var(--transition-fast);
}

.related-card:hover .related-card__arrow {
  transform: translateX(3px);
  color: var(--color-primary);
}


/* ==========================================================================
   Definition Block
   ========================================================================== */

.definition-block {
  max-width: 680px;
  margin: var(--space-10) auto 0;
}

.definition-block__inner {
  padding: var(--space-6) var(--space-8);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 3px solid var(--color-primary);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
}

.definition-block__title {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-3);
}

.definition-block__text {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

.definition-block__text + .definition-block__text {
  margin-top: var(--space-3);
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-border-light);
  font-weight: 500;
  color: var(--color-text);
}


/* ==========================================================================
   Popular Volume Units Diagram
   ========================================================================== */

.popular-units {
  max-width: 680px;
  margin: var(--space-10) auto 0;
}

.popular-units__title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-2);
  text-align: center;
}

.popular-units__desc {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  text-align: center;
  margin-bottom: var(--space-6);
  line-height: var(--leading-relaxed);
}

.unit-conversion-diagram {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  justify-content: center;
}

.unit-node {
  padding: var(--space-2) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-text-secondary);
}

.unit-node:hover,
.unit-node--active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: #fff;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.2);
}

.unit-node__label {
  pointer-events: none;
}

.unit-conversion-result {
  margin-top: var(--space-4);
  text-align: center;
  padding: var(--space-3) var(--space-5);
  background: var(--gradient-primary-soft);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
}

.unit-conversion-result__text {
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--color-primary);
}


/* ==========================================================================
   Unit Explainer (Two-column layout)
   ========================================================================== */

.unit-explainer {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-12);
  align-items: start;
  margin-bottom: var(--space-16);
}

.unit-explainer:last-child {
  margin-bottom: 0;
}

.unit-explainer--reverse {
  direction: rtl;
}

.unit-explainer--reverse > * {
  direction: ltr;
}

.unit-explainer__content {
  display: flex;
  flex-direction: column;
  gap: var(--space-5);
}

.unit-explainer__title {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--color-text);
}

.unit-explainer__content p {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

.sub-section {
  margin-top: var(--space-6);
  padding-top: var(--space-6);
  border-top: 1px solid var(--color-border-light);
}

.sub-section__title {
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-bottom: var(--space-3);
  color: var(--color-text);
}

.conversion-examples {
  list-style: none;
  padding: 0;
  margin: var(--space-3) 0;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.conversion-examples li {
  padding: var(--space-2) var(--space-4);
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  border-left: 2px solid var(--color-primary);
}

.conversion-examples li strong {
  color: var(--color-primary);
}


/* ==========================================================================
   Mini Conversion Table
   ========================================================================== */

.mini-table-wrap {
  overflow-x: auto;
  margin-top: var(--space-3);
}

.mini-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  font-size: var(--font-size-sm);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.mini-table thead th {
  padding: var(--space-3) var(--space-4);
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
  text-align: left;
}

.mini-table tbody td {
  padding: var(--space-2) var(--space-4);
  border-bottom: 1px solid var(--color-border-light);
  color: var(--color-text-secondary);
}

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

.mini-table tbody tr:hover {
  background: var(--color-primary-50);
}


/* ==========================================================================
   Unit Equivalents Grid
   ========================================================================== */

.unit-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-3);
  margin-top: var(--space-4);
}

.unit-grid__item {
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  text-align: center;
  transition: all var(--transition-fast);
}

.unit-grid__item:hover {
  border-color: var(--color-primary-light);
  box-shadow: var(--shadow-sm);
  transform: translateY(-2px);
}

.unit-grid__value {
  display: block;
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--color-primary);
}

.unit-grid__label {
  display: block;
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  margin-top: 2px;
}


/* ==========================================================================
   US vs Imperial Comparison Diagram
   ========================================================================== */

.comparison-diagram {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.comparison-diagram__title {
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-bottom: var(--space-5);
  text-align: center;
}

.comparison-bars {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.comparison-bar__label {
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-text-muted);
  margin-bottom: var(--space-1);
}

.comparison-bar__track {
  height: 36px;
  background: var(--color-bg-subtle);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.comparison-bar__fill {
  height: 100%;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  padding: 0 var(--space-3);
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: #fff;
  transition: width 1s ease;
}

.comparison-bar__fill--us {
  background: var(--color-primary);
}

.comparison-bar__fill--imperial {
  background: var(--color-secondary);
}

.comparison-diagram__note {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  margin-top: var(--space-4);
  line-height: var(--leading-relaxed);
  text-align: center;
}


/* ==========================================================================
   Container Sizes (Interactive Buttons)
   ========================================================================== */

.container-sizes {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-sm);
}

.container-sizes__title {
  font-size: var(--font-size-base);
  font-weight: 600;
  margin-bottom: var(--space-2);
  text-align: center;
}

.container-sizes__desc {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  text-align: center;
  margin-bottom: var(--space-5);
  line-height: var(--leading-relaxed);
}

.container-sizes__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-3);
}

.container-size-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-4) var(--space-3);
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--color-primary);
}

.container-size-btn:hover {
  background: var(--color-primary-50);
  border-color: var(--color-primary-light);
  transform: translateY(-2px);
  box-shadow: var(--shadow-sm);
}

.container-size-btn__name {
  font-size: var(--font-size-xs);
  font-weight: 600;
  color: var(--color-text);
}

.container-size-btn__oz {
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--color-primary);
}

.container-size-btn__litres {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
}


/* ==========================================================================
   Formula Section
   ========================================================================== */

.formula-section {
  max-width: 800px;
  margin: 0 auto var(--space-16);
}

.formula-section__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-6);
}

.formula-section p {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin-top: var(--space-4);
}

.formula-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-8) var(--space-10);
  text-align: center;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.formula-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-primary);
}

.formula-card__equation {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-3);
  flex-wrap: wrap;
  margin-bottom: var(--space-5);
}

.formula-card__var {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-text);
  padding: var(--space-2) var(--space-4);
  background: var(--color-bg-alt);
  border-radius: var(--radius-sm);
}

.formula-card__var-sm {
  font-size: var(--font-size-sm);
  font-weight: 600;
  color: var(--color-text-secondary);
}

.formula-card__equals,
.formula-card__operator {
  font-size: var(--font-size-2xl);
  font-weight: 300;
  color: var(--color-text-muted);
}

.formula-card__constant {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--color-primary);
  padding: var(--space-2) var(--space-4);
  background: var(--color-primary-50);
  border-radius: var(--radius-sm);
}

.formula-card__constant-sm {
  font-size: var(--font-size-sm);
  font-weight: 700;
  color: var(--color-secondary);
}

.formula-card__reverse {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding-top: var(--space-4);
  border-top: 1px dashed var(--color-border);
}

.formula-card__label {
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  font-weight: 500;
}

.formula-card__reverse .formula-card__equals,
.formula-card__reverse .formula-card__operator {
  font-size: var(--font-size-sm);
}


/* ==========================================================================
   Step-by-Step Calculator
   ========================================================================== */

.manual-steps {
  max-width: 800px;
  margin: 0 auto;
}

.manual-steps__title {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--space-6);
}

.manual-steps p {
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin-top: var(--space-4);
}

.step-calculator {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  box-shadow: var(--shadow-md);
}

.step-calculator__input-row {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-6);
  padding-bottom: var(--space-5);
  border-bottom: 1px solid var(--color-border-light);
}

.step-calculator__label {
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-text-secondary);
  white-space: nowrap;
}

.step-calculator__input {
  width: 100px;
  padding: var(--space-2) var(--space-3);
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: var(--color-text);
  background: var(--color-bg-alt);
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  transition: border-color var(--transition-fast);
}

.step-calculator__input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.step-calculator__unit {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  font-weight: 500;
}

.step-calculator__steps {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}

.step-calc-item {
  display: flex;
  align-items: flex-start;
  gap: var(--space-4);
}

.step-calc-item__number {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  background: var(--color-bg-subtle);
  color: var(--color-text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-sm);
  font-weight: 600;
  flex-shrink: 0;
}

.step-calc-item--final .step-calc-item__number {
  background: var(--color-primary);
  color: #fff;
}

.step-calc-item__content {
  flex: 1;
}

.step-calc-item__text {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  margin-bottom: var(--space-1);
}

.step-calc-item__result {
  font-size: var(--font-size-base);
  font-weight: 600;
  color: var(--color-text);
  font-family: 'Courier New', monospace;
}

.step-calc-item__result--highlight {
  font-size: var(--font-size-lg);
  color: var(--color-primary);
  font-family: var(--font-family);
}


/* ==========================================================================
   Conversion Table
   ========================================================================== */

.table-section__controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
  gap: var(--space-4);
  flex-wrap: wrap;
}

.table-search {
  position: relative;
  flex: 0 1 300px;
}

.table-search__input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  padding-left: 40px;
  font-size: var(--font-size-sm);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--transition-fast);
  color: var(--color-text);
}

.table-search__input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.08);
}

.table-search__icon {
  position: absolute;
  left: var(--space-3);
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--color-text-muted);
  pointer-events: none;
}

.table-tabs {
  display: flex;
  gap: var(--space-1);
  background: var(--color-bg-subtle);
  border-radius: var(--radius-sm);
  padding: 2px;
}

.table-tab {
  padding: var(--space-2) var(--space-4);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-text-muted);
  border-radius: 6px;
  transition: all var(--transition-fast);
  cursor: pointer;
  border: none;
  background: none;
}

.table-tab--active {
  background: var(--color-bg);
  color: var(--color-text);
  box-shadow: var(--shadow-xs);
}

.table-tab:hover:not(.table-tab--active) {
  color: var(--color-text-secondary);
}

.conversion-table {
  width: 100%;
  border-collapse: separate;
  border-spacing: 0;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1px solid var(--color-border);
}

.conversion-table thead th {
  padding: var(--space-4) var(--space-5);
  font-size: var(--font-size-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--color-text-muted);
  background: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
  text-align: left;
}

.conversion-table tbody td {
  padding: var(--space-3) var(--space-5);
  font-size: var(--font-size-sm);
  border-bottom: 1px solid var(--color-border-light);
  transition: background var(--transition-fast);
}

.conversion-table tbody tr {
  cursor: pointer;
  transition: background var(--transition-fast);
}

.conversion-table tbody tr:hover {
  background: var(--color-primary-50);
}

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

.conversion-table .table__oz {
  font-weight: 600;
  color: var(--color-text);
}

.conversion-table .table__liters {
  font-weight: 600;
  color: var(--color-primary);
}

.conversion-table .table__notes {
  color: var(--color-text-muted);
  font-size: var(--font-size-xs);
}

.conversion-table .table__action {
  text-align: right;
}

.conversion-table .table__use-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-3);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: var(--color-primary);
  background: var(--color-primary-50);
  border-radius: var(--radius-sm);
  border: none;
  cursor: pointer;
  opacity: 0;
  transition: all var(--transition-fast);
}

.conversion-table tbody tr:hover .table__use-btn {
  opacity: 1;
}

.conversion-table .table__use-btn:hover {
  background: var(--color-primary);
  color: #fff;
}



/* ==========================================================================
   FAQ Accordion
   ========================================================================== */

.faq__list {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.faq-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: box-shadow var(--transition-base), border-color var(--transition-fast);
}

.faq-item:hover {
  border-color: var(--color-primary-light);
}

.faq-item.is-open {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary-light);
}

.faq-item__question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  width: 100%;
  padding: var(--space-5) var(--space-6);
  font-size: var(--font-size-base);
  font-weight: 500;
  color: var(--color-text);
  text-align: left;
  cursor: pointer;
  border: none;
  background: none;
  transition: color var(--transition-fast);
}

.faq-item__question:hover {
  color: var(--color-primary);
}

.faq-item__icon {
  width: 24px;
  height: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  color: var(--color-text-muted);
  transition: transform var(--transition-base), color var(--transition-fast);
}

.faq-item.is-open .faq-item__icon {
  transform: rotate(45deg);
  color: var(--color-primary);
}

.faq-item__answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
}

.faq-item__answer-inner {
  padding: 0 var(--space-6) var(--space-6);
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
}

.faq-item__answer-inner p + p {
  margin-top: var(--space-3);
}




/* ==========================================================================
   Footer — 4 Column Layout
   ========================================================================== */

.footer {
  padding: var(--space-16) 0 var(--space-8);
  background: #0F172A;
  color: #CBD5E1;
}

.footer__grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1.3fr;
  gap: var(--space-10);
  margin-bottom: var(--space-12);
}

.footer__col-title {
  font-size: var(--font-size-base);
  font-weight: 600;
  color: #F1F5F9;
  margin-bottom: var(--space-5);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Brand */
.footer__brand {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}

.footer__brand-icon {
  width: 36px;
  height: 36px;
  border-radius: 10px;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-size: var(--font-size-sm);
  font-weight: 700;
}

.footer__brand-name {
  font-size: var(--font-size-lg);
  font-weight: 600;
  color: #F1F5F9;
}

.footer__brand-name em {
  font-style: normal;
  color: var(--color-primary);
}

.footer__tagline {
  font-size: var(--font-size-sm);
  line-height: var(--leading-relaxed);
  color: #94A3B8;
  margin-bottom: var(--space-6);
}

/* Social Icons */
.footer__social {
  display: flex;
  gap: var(--space-3);
}

.footer__social-link {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  border: 1px solid #334155;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #94A3B8;
  transition: all var(--transition-fast);
}

.footer__social-link:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  background: rgba(37, 99, 235, 0.1);
}

/* Links */
.footer__link {
  display: block;
  font-size: var(--font-size-sm);
  color: #94A3B8;
  padding: var(--space-2) 0;
  transition: color var(--transition-fast);
}

.footer__link:hover {
  color: #F1F5F9;
}

/* Contact */
.footer__contact-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: var(--font-size-sm);
  color: #94A3B8;
  padding: var(--space-3) 0;
  transition: color var(--transition-fast);
}

.footer__contact-item:hover {
  color: #F1F5F9;
}

.footer__contact-item svg {
  flex-shrink: 0;
  color: var(--color-primary);
}

/* Language Grid */
.footer__lang-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: var(--space-2);
}

.footer__lang-btn {
  padding: var(--space-2) var(--space-3);
  font-size: var(--font-size-xs);
  font-weight: 500;
  color: #94A3B8;
  background: transparent;
  border: 1px solid #334155;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
}

.footer__lang-btn:hover {
  border-color: var(--color-primary);
  color: #F1F5F9;
  background: rgba(37, 99, 235, 0.08);
}

.footer__lang-btn--active {
  border-color: var(--color-primary);
  color: #F1F5F9;
  background: rgba(37, 99, 235, 0.15);
}

/* Bottom */
.footer__bottom {
  border-top: 1px solid #1E293B;
  padding-top: var(--space-8);
  text-align: center;
  font-size: var(--font-size-sm);
  color: #64748B;
}


/* ==========================================================================
   Scroll Animations
   ========================================================================== */

.animate-on-scroll {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.animate-on-scroll.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.animate-on-scroll[data-delay="100"] { transition-delay: 100ms; }
.animate-on-scroll[data-delay="200"] { transition-delay: 200ms; }
.animate-on-scroll[data-delay="300"] { transition-delay: 300ms; }
.animate-on-scroll[data-delay="400"] { transition-delay: 400ms; }


/* The cup wave path is calculated in JS so small values stay at the bottom. */
.wave-path {
  transition: d var(--transition-base);
}



/* ==========================================================================
   Responsive — Tablet (≤ 768px)
   ========================================================================== */

@media (max-width: 768px) {
  :root {
    --font-size-5xl: 2.25rem;
    --font-size-4xl: 1.875rem;
    --font-size-3xl: 1.5rem;
  }

  .section {
    padding: var(--space-16) 0;
  }

  .section__header {
    margin-bottom: var(--space-10);
  }

  .section__subtitle,
  .hero__subtitle,
  .unit-explainer__content p,
  .manual-steps p {
    overflow-wrap: break-word;
  }

  .nav__links {
    display: none;
  }

  .nav__links.is-open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: var(--nav-height);
    left: 0;
    right: 0;
    background: var(--color-bg);
    border-bottom: 1px solid var(--color-border);
    padding: var(--space-4) var(--space-6);
    gap: var(--space-4);
    box-shadow: var(--shadow-lg);
  }

  .nav__mobile-toggle {
    display: flex;
  }

  .converter__fields {
    flex-direction: column;
    gap: var(--space-3);
  }

  .converter__swap {
    align-self: center;
    transform: rotate(90deg);
  }

  .converter__swap:hover {
    transform: rotate(270deg);
  }

  .converter__card {
    padding: var(--space-6);
  }

  .hero__title .text-gradient {
    display: block;
  }

  .visual-converter {
    grid-template-columns: 1fr;
    gap: var(--space-10);
    padding: var(--space-6);
  }

  .how-it-works__grid {
    grid-template-columns: 1fr;
  }

  .step-card {
    min-height: auto;
  }

  .measuring-cup__container {
    width: min(100%, 240px);
  }

  .scale-input {
    max-width: none;
  }

  .unit-explainer {
    grid-template-columns: 1fr;
    gap: var(--space-8);
    margin-bottom: var(--space-12);
  }

  .unit-explainer--reverse {
    direction: ltr;
  }

  .unit-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .container-sizes__grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .containers__grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .info-cards__grid {
    grid-template-columns: 1fr;
  }

  .related-converters__grid {
    grid-template-columns: 1fr;
  }

  .footer__grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-8);
  }

  .converter__actions {
    flex-direction: column;
  }

  .trust-badges {
    flex-direction: column;
    gap: var(--space-4);
  }

  .table-section__controls {
    flex-direction: column;
    align-items: stretch;
  }

  .table-search {
    flex: 1;
  }

  .conversion-table {
    display: block;
    overflow-x: auto;
  }

  .formula-card__equation {
    gap: var(--space-2);
  }

  .formula-card__var,
  .formula-card__constant,
  .formula-card__equals,
  .formula-card__operator {
    font-size: var(--font-size-xl);
  }

  .step-calculator__input-row {
    flex-wrap: wrap;
  }
}

/* ==========================================================================
   Responsive — Small Phones / Narrow Preview Panes (≤ 640px)
   ========================================================================== */

@media (max-width: 640px) {
  html,
  body {
    width: 100%;
    max-width: 100%;
  }

  .nav,
  main,
  .footer {
    width: 100%;
    max-width: 100%;
  }

  .container {
    width: 100%;
    max-width: 100%;
    margin-left: auto;
    margin-right: auto;
    padding: 0 var(--space-4);
  }

  .nav__inner {
    width: 100%;
    max-width: 100%;
    margin-left: auto;
    margin-right: auto;
  }

  .hero *,
  .section *,
  .footer * {
    min-width: 0;
  }

  .hero__content,
  .section__header,
  .hero__subtitle,
  .section__subtitle,
  .definition-block,
  .popular-units,
  .converter,
  .formula-section,
  .manual-steps {
    max-width: 100%;
  }

  .hero__title .text-gradient {
    display: block;
  }

  .converter__card,
  .definition-block__inner,
  .visual-converter,
  .comparison-diagram,
  .container-sizes,
  .formula-card,
  .step-calculator,
  .info-card,
  .faq-item {
    width: 100%;
    max-width: 100%;
  }

  .converter__result-bar {
    flex-direction: column;
    align-items: stretch;
  }

  .converter__copy-btn {
    justify-content: center;
  }

  .unit-conversion-diagram,
  .table-tabs {
    display: grid;
    grid-template-columns: 1fr;
    width: 100%;
  }

  .unit-node,
  .table-tab {
    width: 100%;
  }

  .unit-grid,
  .container-sizes__grid,
  .how-it-works__grid,
  .containers__grid {
    grid-template-columns: 1fr;
  }

  .formula-card__equation,
  .formula-card__reverse {
    flex-direction: column;
    align-items: stretch;
  }

  .formula-card__var,
  .formula-card__constant {
    width: 100%;
  }

  .step-calculator__input-row {
    display: grid;
    grid-template-columns: 1fr;
    align-items: stretch;
  }

  .step-calculator__input {
    width: 100%;
  }

  .related-card {
    grid-template-columns: auto minmax(0, 1fr);
  }

  .related-card__arrow {
    display: none;
  }
}


/* ==========================================================================
   Responsive — Mobile (≤ 480px)
   ========================================================================== */

@media (max-width: 480px) {
  :root {
    --font-size-5xl: 1.875rem;
    --font-size-4xl: 1.5rem;
    --font-size-2xl: 1.25rem;
  }

  .container {
    padding: 0 var(--space-4);
  }

  .nav__inner {
    padding: 0 var(--space-4);
  }

  .nav__logo {
    font-size: var(--font-size-base);
  }

  .nav__logo-icon {
    width: 32px;
    height: 32px;
  }

  .hero {
    padding-top: calc(var(--nav-height) + var(--space-8));
    padding-bottom: var(--space-12);
  }

  .hero__content {
    margin-bottom: var(--space-8);
  }

  .hero__badge,
  .section__badge {
    max-width: 100%;
    white-space: normal;
    text-align: center;
    justify-content: center;
    letter-spacing: 0;
  }

  .hero__title {
    font-size: 2rem;
    line-height: 1.15;
  }

  .section__title {
    overflow-wrap: break-word;
  }

  .converter__card {
    padding: var(--space-4);
    border-radius: var(--radius-lg);
  }

  .hero__subtitle {
    font-size: var(--font-size-base);
  }

  .converter__input {
    font-size: var(--font-size-xl);
  }

  .converter__result-bar {
    flex-direction: column;
    align-items: flex-start;
    padding: var(--space-3) var(--space-4);
  }

  .converter__copy-btn {
    align-self: stretch;
    justify-content: center;
  }

  .btn {
    width: 100%;
    min-height: 48px;
  }

  .definition-block__inner,
  .visual-converter,
  .comparison-diagram,
  .container-sizes,
  .formula-card,
  .step-calculator {
    padding: var(--space-4);
    border-radius: var(--radius-md);
  }

  .popular-units,
  .definition-block {
    margin-top: var(--space-8);
  }

  .unit-conversion-diagram {
    justify-content: stretch;
  }

  .unit-node {
    width: 100%;
    border-radius: var(--radius-sm);
  }

  .measuring-cup__container {
    width: min(100%, 220px);
    padding: var(--space-3);
  }

  .measuring-cup__value {
    font-size: var(--font-size-base);
  }

  .scale-panel__title,
  .unit-explainer__title,
  .formula-section__title,
  .manual-steps__title {
    font-size: var(--font-size-xl);
  }

  .scale-result__value {
    font-size: var(--font-size-3xl);
  }

  .scale-bar__labels {
    font-size: 0.6875rem;
  }

  .comparison-bar__fill {
    min-width: 0;
    padding: 0 var(--space-2);
    font-size: 0.75rem;
  }

  .containers__grid {
    grid-template-columns: 1fr;
  }

  .unit-grid,
  .container-sizes__grid {
    grid-template-columns: 1fr;
  }

  .container-card,
  .container-size-btn {
    min-height: auto;
  }

  .formula-card__equation,
  .formula-card__reverse {
    flex-direction: column;
    align-items: stretch;
  }

  .formula-card__var,
  .formula-card__constant {
    width: 100%;
  }

  .step-calculator__input-row {
    display: grid;
    grid-template-columns: 1fr;
    align-items: stretch;
  }

  .step-calculator__input {
    width: 100%;
  }

  .step-calc-item {
    gap: var(--space-3);
  }

  .step-calc-item__result {
    overflow-wrap: anywhere;
  }

  .table-tabs {
    width: 100%;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
  }

  .table-tab {
    padding: var(--space-2);
  }

  .conversion-table {
    font-size: var(--font-size-xs);
  }

  .conversion-table thead th,
  .conversion-table tbody td {
    padding: var(--space-3);
    white-space: nowrap;
  }

  .info-card__header {
    grid-template-columns: auto minmax(0, 1fr) auto;
    gap: var(--space-3);
    padding: var(--space-4);
  }

  .info-card__icon {
    width: 36px;
    height: 36px;
  }

  .related-card {
    grid-template-columns: auto minmax(0, 1fr);
  }

  .related-card__arrow {
    display: none;
  }

  .footer__grid {
    grid-template-columns: 1fr;
    gap: var(--space-8);
  }

  .footer__lang-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .footer__contact-item {
    align-items: flex-start;
    overflow-wrap: anywhere;
  }
}


/* ==========================================================================
   Focus & Accessibility
   ========================================================================== */

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .animate-on-scroll {
    opacity: 1;
    transform: none;
  }
}