/* ============================================
   SILVER SCRAP CALCULATOR — DESIGN SYSTEM
   Premium Dark Theme with Silver/Metallic Accents
   ============================================ */

/* ---- Google Fonts ---- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&family=Outfit:wght@400;500;600;700;800&display=swap');

/* ---- CSS Custom Properties ---- */
:root {
  /* Core Palette */
  --bg-primary: #0a0a0f;
  --bg-secondary: #111118;
  --bg-tertiary: #1a1a24;
  --bg-card: rgba(255, 255, 255, 0.03);
  --bg-card-hover: rgba(255, 255, 255, 0.06);
  --bg-glass: rgba(255, 255, 255, 0.04);
  --bg-glass-strong: rgba(255, 255, 255, 0.08);

  /* Silver / Metallic Accents */
  --silver-50: #f8f9fa;
  --silver-100: #e8eaed;
  --silver-200: #c4c8cf;
  --silver-300: #a0a7b2;
  --silver-400: #7c8594;
  --silver-500: #5a6478;
  --silver-600: #454d5e;
  --silver-700: #313845;
  --silver-800: #1e232d;

  /* Accent Colors */
  --accent-primary: #c0c0c0;
  --accent-glow: rgba(192, 192, 192, 0.3);
  --accent-blue: #4a9eff;
  --accent-blue-glow: rgba(74, 158, 255, 0.15);
  --accent-green: #34d399;
  --accent-green-glow: rgba(52, 211, 153, 0.15);
  --accent-gold: #fbbf24;
  --accent-gold-glow: rgba(251, 191, 36, 0.15);
  --accent-purple: #a78bfa;

  /* Text Colors */
  --text-primary: #f0f0f5;
  --text-secondary: #a0a4b8;
  --text-muted: #6b7084;
  --text-accent: #c0c0c0;

  /* Borders */
  --border-subtle: rgba(255, 255, 255, 0.06);
  --border-medium: rgba(255, 255, 255, 0.1);
  --border-strong: rgba(255, 255, 255, 0.15);
  --border-accent: rgba(192, 192, 192, 0.3);

  /* Gradients */
  --gradient-silver: linear-gradient(135deg, #c0c0c0 0%, #e8e8e8 50%, #a8a8a8 100%);
  --gradient-hero: linear-gradient(180deg, rgba(192,192,192,0.08) 0%, transparent 60%);
  --gradient-card: linear-gradient(145deg, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0.01) 100%);
  --gradient-btn: linear-gradient(135deg, #c0c0c0 0%, #e0e0e0 50%, #b0b0b0 100%);

  /* Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 20px rgba(192, 192, 192, 0.1);
  --shadow-glow-strong: 0 0 40px rgba(192, 192, 192, 0.2);

  /* Typography */
  --font-display: 'Outfit', sans-serif;
  --font-body: 'Inter', sans-serif;
  --fs-xs: 0.75rem;
  --fs-sm: 0.875rem;
  --fs-base: 1rem;
  --fs-md: 1.125rem;
  --fs-lg: 1.25rem;
  --fs-xl: 1.5rem;
  --fs-2xl: 2rem;
  --fs-3xl: 2.5rem;
  --fs-4xl: 3.5rem;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;
  --space-4xl: 6rem;

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

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s ease;
  --transition-spring: 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Layout */
  --max-width: 1200px;
  --header-height: 72px;
}

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

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

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

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

a:hover {
  color: var(--silver-50);
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

button, input, select, textarea {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
}

/* ---- Utility Classes ---- */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

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

.text-center { text-align: center; }
.text-muted { color: var(--text-muted); }
.text-secondary { color: var(--text-secondary); }
.text-accent { color: var(--accent-primary); }

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

/* ---- Typography ---- */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  color: var(--text-primary);
}

h1 {
  font-size: var(--fs-3xl);
  font-weight: 800;
  letter-spacing: -0.03em;
}

h2 {
  font-size: var(--fs-2xl);
  font-weight: 700;
  letter-spacing: -0.02em;
}

h3 {
  font-size: var(--fs-xl);
  font-weight: 600;
}

h4 {
  font-size: var(--fs-lg);
  font-weight: 600;
}

p {
  color: var(--text-secondary);
  line-height: 1.7;
}

.section-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-xs) var(--space-md);
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  font-size: var(--fs-xs);
  font-weight: 500;
  color: var(--accent-primary);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-lg);
}

.section-title {
  margin-bottom: var(--space-md);
}

.section-subtitle {
  color: var(--text-secondary);
  font-size: var(--fs-md);
  max-width: 640px;
  margin: 0 auto var(--space-2xl);
}

/* ---- Header & Navigation ---- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--header-height);
  background: rgba(10, 10, 15, 0.85);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-subtle);
  transition: background var(--transition-base);
}

.site-header.scrolled {
  background: rgba(10, 10, 15, 0.95);
  box-shadow: var(--shadow-md);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--space-lg);
}

.header-logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-lg);
  color: var(--text-primary);
  text-decoration: none;
}

.header-logo .logo-icon {
  width: 36px;
  height: 36px;
  background: var(--gradient-silver);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 18px;
  color: var(--bg-primary);
  font-weight: 800;
}

.header-logo span {
  background: var(--gradient-silver);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Desktop Nav */
.main-nav {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
}

.nav-link {
  padding: var(--space-sm) var(--space-md);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.nav-link:hover,
.nav-link.active {
  color: var(--text-primary);
  background: var(--bg-glass);
}

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

/* Nav Dropdown */
.nav-dropdown {
  position: relative;
}

.nav-dropdown-trigger {
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
}

.nav-dropdown-trigger::after {
  content: '▾';
  font-size: 10px;
  transition: transform var(--transition-fast);
}

.nav-dropdown:hover .nav-dropdown-trigger::after {
  transform: rotate(180deg);
}

.nav-dropdown-menu {
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%) translateY(8px);
  min-width: 220px;
  background: var(--bg-secondary);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: var(--space-sm);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-fast);
}

.nav-dropdown:hover .nav-dropdown-menu {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

.nav-dropdown-menu a {
  display: block;
  padding: var(--space-sm) var(--space-md);
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

.nav-dropdown-menu a:hover {
  color: var(--text-primary);
  background: var(--bg-glass);
}

/* Mobile Menu Toggle */
.mobile-menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  padding: 8px;
  background: none;
  border: none;
  cursor: pointer;
  z-index: 1001;
}

.mobile-menu-btn span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition-base);
}

.mobile-menu-btn.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.mobile-menu-btn.active span:nth-child(2) {
  opacity: 0;
}

.mobile-menu-btn.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* Mobile Nav Overlay */
.mobile-nav {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  height: 100vh;
  background: var(--bg-primary);
  z-index: 999;
  padding: var(--space-xl);
  padding-bottom: 120px;
  overflow-y: auto;
}

.mobile-nav.open {
  display: block;
  animation: fadeIn 0.3s ease;
}

.mobile-nav a {
  display: block;
  padding: var(--space-md) 0;
  font-size: var(--fs-md);
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border-subtle);
}

.mobile-nav a:hover {
  color: var(--text-primary);
}

.mobile-nav-group-title {
  font-size: var(--fs-xs);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  margin-top: var(--space-xl);
  margin-bottom: var(--space-sm);
}

/* ---- Main Content ---- */
main {
  padding-top: var(--header-height);
}

/* ---- Hero Section ---- */
.hero {
  position: relative;
  padding: var(--space-4xl) 0 var(--space-3xl);
  background: var(--gradient-hero);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(192,192,192,0.06) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  text-align: center;
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: var(--fs-4xl);
  margin-bottom: var(--space-lg);
}

.hero h1 .highlight {
  background: var(--gradient-silver);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: var(--fs-lg);
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-2xl);
}

/* ---- Live Price Ticker ---- */
.price-ticker {
  display: inline-flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-sm) var(--space-lg);
  background: var(--bg-glass);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-full);
  margin-bottom: var(--space-2xl);
}

.price-ticker .dot {
  width: 8px;
  height: 8px;
  background: var(--accent-green);
  border-radius: 50%;
  animation: pulse 2s infinite;
}

.price-ticker .label {
  font-size: var(--fs-sm);
  color: var(--text-muted);
}

.price-ticker .price {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-lg);
  color: var(--text-primary);
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

/* ---- Glass Card ---- */
.glass-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: all var(--transition-base);
}

.glass-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-medium);
  box-shadow: var(--shadow-glow);
  transform: translateY(-2px);
}

/* ---- Calculator Widget ---- */
.calc-widget {
  background: var(--bg-glass);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-xl);
  padding: var(--space-2xl);
  max-width: 560px;
  margin: 0 auto;
  position: relative;
  overflow: hidden;
}

.calc-widget::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--accent-primary), transparent);
}

.calc-widget-title {
  font-family: var(--font-display);
  font-size: var(--fs-lg);
  font-weight: 600;
  margin-bottom: var(--space-xl);
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.calc-widget-title .icon {
  font-size: var(--fs-xl);
}

/* Form Elements */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-label {
  display: block;
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
}

.form-input,
.form-select {
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  background: var(--bg-secondary);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: var(--fs-base);
  transition: all var(--transition-fast);
  outline: none;
}

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

.form-input::placeholder {
  color: var(--text-muted);
}

.form-select {
  appearance: none;
  -webkit-appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' fill='%23a0a4b8' viewBox='0 0 16 16'%3E%3Cpath d='M8 11L3 6h10l-5 5z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 16px center;
  padding-right: 44px;
  cursor: pointer;
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-md);
}

.input-group {
  position: relative;
}

.input-group .unit {
  position: absolute;
  right: var(--space-md);
  top: 50%;
  transform: translateY(-50%);
  font-size: var(--fs-sm);
  color: var(--text-muted);
  pointer-events: none;
}

/* ---- Result Display ---- */
.result-display {
  background: linear-gradient(135deg, rgba(192,192,192,0.08) 0%, rgba(192,192,192,0.02) 100%);
  border: 1px solid var(--border-accent);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-align: center;
  margin-top: var(--space-xl);
}

.result-label {
  font-size: var(--fs-sm);
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: var(--space-sm);
}

.result-value {
  font-family: var(--font-display);
  font-size: var(--fs-3xl);
  font-weight: 800;
  background: var(--gradient-silver);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.result-detail {
  font-size: var(--fs-sm);
  color: var(--text-muted);
  margin-top: var(--space-sm);
}

/* ---- Buttons ---- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-xl);
  font-family: var(--font-display);
  font-weight: 600;
  font-size: var(--fs-sm);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-base);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-btn);
  color: var(--bg-primary);
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover {
  box-shadow: var(--shadow-glow-strong);
  transform: translateY(-1px);
  color: var(--bg-primary);
}

.btn-secondary {
  background: var(--bg-glass-strong);
  color: var(--text-primary);
  border: 1px solid var(--border-medium);
}

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

.btn-lg {
  padding: var(--space-lg) var(--space-2xl);
  font-size: var(--fs-base);
  border-radius: var(--radius-lg);
}

.btn-full {
  width: 100%;
}

/* ---- Category Grid ---- */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: var(--space-xl);
}

.category-card {
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  text-decoration: none;
  transition: all var(--transition-base);
}

.category-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-medium);
  box-shadow: var(--shadow-glow);
  transform: translateY(-4px);
}

.category-icon {
  width: 48px;
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  background: var(--bg-glass-strong);
  border-radius: var(--radius-md);
  margin-bottom: var(--space-lg);
}

.category-card h3 {
  font-size: var(--fs-md);
  margin-bottom: var(--space-sm);
  color: var(--text-primary);
}

.category-card p {
  font-size: var(--fs-sm);
  color: var(--text-muted);
  flex: 1;
}

.category-card .card-arrow {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: var(--space-lg);
  font-size: var(--fs-sm);
  font-weight: 500;
  color: var(--accent-primary);
  transition: gap var(--transition-fast);
}

.category-card:hover .card-arrow {
  gap: 8px;
}

/* ---- How It Works ---- */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-xl);
  counter-reset: step;
}

.step-card {
  position: relative;
  text-align: center;
  padding: var(--space-xl);
}

.step-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background: var(--bg-glass-strong);
  border: 1px solid var(--border-medium);
  border-radius: 50%;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: var(--fs-lg);
  color: var(--accent-primary);
  margin-bottom: var(--space-lg);
}

.step-card h4 {
  margin-bottom: var(--space-sm);
}

.step-card p {
  font-size: var(--fs-sm);
}

/* ---- Trust Signals ---- */
.trust-bar {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: var(--space-2xl);
  padding: var(--space-2xl) 0;
  border-top: 1px solid var(--border-subtle);
  border-bottom: 1px solid var(--border-subtle);
}

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

.trust-item .icon {
  font-size: var(--fs-lg);
}

/* ---- SEO Content Section ---- */
.content-section {
  padding: var(--space-3xl) 0;
}

.content-section .content-body {
  max-width: 800px;
  margin: 0 auto;
}

.content-body h2 {
  font-size: var(--fs-xl);
  margin: var(--space-2xl) 0 var(--space-md);
}

.content-body h3 {
  font-size: var(--fs-lg);
  margin: var(--space-xl) 0 var(--space-md);
}

.content-body p {
  margin-bottom: var(--space-md);
}

.content-body ul {
  margin: var(--space-md) 0;
  padding-left: var(--space-xl);
  list-style: disc;
}

.content-body ul li {
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
  line-height: 1.7;
}

.content-body a {
  color: var(--accent-blue);
  text-decoration: underline;
  text-decoration-color: rgba(74, 158, 255, 0.3);
  text-underline-offset: 2px;
}

.content-body a:hover {
  text-decoration-color: var(--accent-blue);
}

/* ---- Purity Table ---- */
.purity-table {
  width: 100%;
  border-collapse: collapse;
  margin: var(--space-xl) 0;
}

.purity-table th,
.purity-table td {
  padding: var(--space-md);
  text-align: left;
  border-bottom: 1px solid var(--border-subtle);
}

.purity-table th {
  font-size: var(--fs-sm);
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.purity-table td {
  color: var(--text-secondary);
}

.purity-table tr:hover td {
  background: var(--bg-glass);
}

/* ---- Related Calculators ---- */
.related-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: var(--space-md);
}

.related-link {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  transition: all var(--transition-fast);
}

.related-link:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  border-color: var(--border-medium);
}

.related-link .r-icon {
  font-size: var(--fs-md);
}

/* ---- FAQ Section ---- */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  border-bottom: 1px solid var(--border-subtle);
}

.faq-question {
  width: 100%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-lg) 0;
  background: none;
  border: none;
  color: var(--text-primary);
  font-size: var(--fs-base);
  font-weight: 500;
  text-align: left;
  cursor: pointer;
  transition: color var(--transition-fast);
}

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

.faq-question .faq-icon {
  font-size: var(--fs-lg);
  transition: transform var(--transition-base);
  flex-shrink: 0;
  margin-left: var(--space-md);
}

.faq-item.open .faq-icon {
  transform: rotate(45deg);
}

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

.faq-item.open .faq-answer {
  max-height: 500px;
}

.faq-answer p {
  padding-bottom: var(--space-lg);
  font-size: var(--fs-sm);
  line-height: 1.8;
}

/* ---- Footer ---- */
.site-footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-subtle);
  padding: var(--space-3xl) 0 var(--space-xl);
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}

.footer-brand p {
  font-size: var(--fs-sm);
  max-width: 280px;
  margin-top: var(--space-md);
}

.footer-col h4 {
  font-size: var(--fs-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
  margin-bottom: var(--space-lg);
}

.footer-col a {
  display: block;
  font-size: var(--fs-sm);
  color: var(--text-secondary);
  padding: var(--space-xs) 0;
  transition: color var(--transition-fast);
}

.footer-col a:hover {
  color: var(--text-primary);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding-top: var(--space-xl);
  border-top: 1px solid var(--border-subtle);
  font-size: var(--fs-xs);
  color: var(--text-muted);
}

/* ---- Page-specific: Calculator Page Layout ---- */
.page-hero {
  padding: var(--space-2xl) 0 var(--space-md);
  text-align: center;
}

.page-hero h1 {
  font-size: var(--fs-3xl);
  margin-bottom: var(--space-md);
}

.page-hero p {
  font-size: var(--fs-md);
  max-width: 600px;
  margin: 0 auto;
}

.calc-page-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-2xl);
  max-width: 900px;
  margin: 0 auto;
  padding: 0 var(--space-lg) var(--space-3xl);
}

/* ---- Breadcrumbs ---- */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) 0;
  font-size: var(--fs-sm);
  color: var(--text-muted);
}

.breadcrumb a {
  color: var(--text-muted);
}

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

.breadcrumb .sep {
  font-size: var(--fs-xs);
}

/* ---- Coin Selector ---- */
.coin-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: var(--space-sm);
}

.coin-btn {
  padding: var(--space-md);
  background: var(--bg-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  color: var(--text-secondary);
  font-size: var(--fs-sm);
  font-weight: 500;
  text-align: center;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.coin-btn:hover {
  border-color: var(--border-medium);
  background: var(--bg-glass);
}

.coin-btn.active {
  border-color: var(--accent-primary);
  background: rgba(192,192,192,0.08);
  color: var(--text-primary);
}

.coin-btn .coin-name {
  display: block;
  font-size: var(--fs-xs);
  color: var(--text-muted);
  margin-top: 4px;
}

/* ---- Guide / Article Page ---- */
.article-layout {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 var(--space-lg) var(--space-3xl);
}

.article-layout h1 {
  font-size: var(--fs-3xl);
  margin-bottom: var(--space-lg);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: var(--space-lg);
  font-size: var(--fs-sm);
  color: var(--text-muted);
  margin-bottom: var(--space-2xl);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--border-subtle);
}

.article-body h2 {
  margin: var(--space-2xl) 0 var(--space-md);
}

.article-body h3 {
  margin: var(--space-xl) 0 var(--space-md);
}

.article-body p {
  margin-bottom: var(--space-md);
}

.article-body ul, .article-body ol {
  margin: var(--space-md) 0;
  padding-left: var(--space-xl);
}

.article-body ul { list-style: disc; }
.article-body ol { list-style: decimal; }

.article-body li {
  color: var(--text-secondary);
  margin-bottom: var(--space-sm);
  line-height: 1.7;
}

.article-body blockquote {
  border-left: 3px solid var(--accent-primary);
  padding: var(--space-md) var(--space-lg);
  background: var(--bg-glass);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: var(--space-lg) 0;
}

.article-body blockquote p {
  color: var(--text-secondary);
  font-style: italic;
}

/* Callout Box */
.callout {
  background: var(--bg-glass);
  border: 1px solid var(--border-medium);
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  margin: var(--space-xl) 0;
}

.callout.info { border-left: 3px solid var(--accent-blue); }
.callout.tip { border-left: 3px solid var(--accent-green); }
.callout.warning { border-left: 3px solid var(--accent-gold); }

.callout-title {
  font-weight: 600;
  margin-bottom: var(--space-sm);
  font-size: var(--fs-sm);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.callout.info .callout-title { color: var(--accent-blue); }
.callout.tip .callout-title { color: var(--accent-green); }
.callout.warning .callout-title { color: var(--accent-gold); }

/* ---- Animations ---- */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes shimmer {
  0% { background-position: -200% center; }
  100% { background-position: 200% center; }
}

.fade-in {
  animation: fadeIn 0.6s ease forwards;
}

.slide-up {
  animation: slideUp 0.6s ease forwards;
}

/* Staggered children */
.stagger > * {
  opacity: 0;
  animation: slideUp 0.5s ease forwards;
}
.stagger > *:nth-child(1) { animation-delay: 0.1s; }
.stagger > *:nth-child(2) { animation-delay: 0.2s; }
.stagger > *:nth-child(3) { animation-delay: 0.3s; }
.stagger > *:nth-child(4) { animation-delay: 0.4s; }
.stagger > *:nth-child(5) { animation-delay: 0.5s; }
.stagger > *:nth-child(6) { animation-delay: 0.6s; }

/* ---- Responsive ---- */
@media (max-width: 1024px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  :root {
    --fs-4xl: 2.5rem;
    --fs-3xl: 2rem;
    --fs-2xl: 1.5rem;
  }

  .main-nav {
    display: none;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .purity-table {
    display: block;
    overflow-x: auto;
    white-space: nowrap;
    -webkit-overflow-scrolling: touch;
  }

  .hero {
    padding: var(--space-xl) 0;
  }

  .calc-widget {
    padding: var(--space-md);
  }

  .form-group {
    margin-bottom: var(--space-md);
  }

  .form-input, .form-select {
    padding: var(--space-sm) var(--space-md);
  }

  .result-display {
    padding: var(--space-md);
    margin-top: var(--space-md);
  }

  .section {
    padding: var(--space-2xl) 0;
  }

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

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

  .footer-bottom {
    flex-direction: column;
    gap: var(--space-md);
    text-align: center;
  }

  .trust-bar {
    gap: var(--space-lg);
  }

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

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

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

@media (max-width: 480px) {
  :root {
    --fs-4xl: 2rem;
    --fs-3xl: 1.75rem;
  }

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

  .price-ticker {
    flex-direction: column;
    gap: var(--space-sm);
  }
}

/* ---- Mobile Language Switcher Visibility ---- */
@media (min-width: 769px) {
  .footer-langs {
    display: none !important;
  }
}

@media (max-width: 768px) {
  html body > .lang-switcher {
    display: none !important; /* Hides the top language switcher generated by translation scripts on mobile */
  }
  
  html body {
    padding-top: var(--header-height) !important;
  }
  
  div#site-header { 
    top: 0 !important; 
  }
}