/* ==========================================================================
   Web2MD-FeedAI Landing Page Stylesheet
   Modern Glassmorphism & High-Tech Dark / Light Dual Theme Design
   ========================================================================== */

/* ---------------- CSS Variables & Design Tokens ---------------- */
:root {
  /* Brand Palette */
  --primary: #10b981;
  --primary-rgb: 16, 185, 129;
  --primary-light: #34d399;
  --primary-dark: #059669;

  --secondary: #06b6d4;
  --secondary-rgb: 6, 182, 212;
  --accent: #8b5cf6;
  --accent-rgb: 139, 92, 246;

  --danger: #ef4444;
  --danger-bg: rgba(239, 68, 68, 0.12);
  --success: #10b981;
  --success-bg: rgba(16, 185, 129, 0.12);

  /* Dark Theme (Default) */
  --bg-main: #0a0f18;
  --bg-surface: #111827;
  --bg-surface-elevated: #1a2234;
  --bg-glass: rgba(17, 24, 39, 0.75);
  --bg-glass-card: rgba(26, 34, 52, 0.6);
  --border-color: rgba(255, 255, 255, 0.1);
  --border-focus: rgba(16, 185, 129, 0.5);

  --text-primary: #f9fafb;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --code-bg: #0d121f;

  /* Elevation Shadows */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 30px rgba(16, 185, 129, 0.25);

  /* Typography */
  --font-main: 'Plus Jakarta Sans', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', Consolas, Monaco, "Courier New", monospace;

  /* Layout */
  --max-width: 1200px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Light Theme Variables */
[data-theme="light"] {
  --bg-main: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-elevated: #f1f5f9;
  --bg-glass: rgba(255, 255, 255, 0.85);
  --bg-glass-card: rgba(255, 255, 255, 0.75);
  --border-color: rgba(0, 0, 0, 0.08);
  --border-focus: rgba(16, 185, 129, 0.6);

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --code-bg: #f1f5f9;

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.07);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.1);
  --shadow-glow: 0 0 30px rgba(16, 185, 129, 0.15);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  overflow-x: hidden;
  max-width: 100%;
  scroll-padding-top: 84px;
}

body {
  font-family: var(--font-main);
  background-color: var(--bg-main);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
  max-width: 100%;
  position: relative;
  min-height: 100vh;
  padding-top: 72px;
  transition: background-color var(--transition-smooth), color var(--transition-smooth);
}

/* Background Atmosphere (Safely contained to avoid mobile horizontal scroll) */
.bg-atmosphere {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  max-height: 2200px;
  overflow: hidden;
  pointer-events: none;
  z-index: 0;
}

.glow-bg {
  position: absolute;
  border-radius: 50%;
  filter: blur(120px);
  pointer-events: none;
  opacity: 0.45;
}

.glow-primary {
  top: -100px;
  left: 15%;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(var(--primary-rgb), 0.35) 0%, transparent 70%);
}

.glow-secondary {
  top: 600px;
  right: 5%;
  width: 550px;
  height: 550px;
  background: radial-gradient(circle, rgba(var(--secondary-rgb), 0.25) 0%, transparent 70%);
}

.grid-pattern {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 1200px;
  background-image: linear-gradient(var(--border-color) 1px, transparent 1px),
    linear-gradient(90deg, var(--border-color) 1px, transparent 1px);
  background-size: 40px 40px;
  background-position: center top;
  mask-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.4) 0%, transparent 80%);
  -webkit-mask-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.4) 0%, transparent 80%);
  pointer-events: none;
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

/* ---------------- Typography & Utilities ---------------- */
h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 700;
  line-height: 1.25;
  color: var(--text-primary);
}

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

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

.gradient-text {
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 50%, var(--accent) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

.text-center {
  text-align: center;
}

.section {
  padding: 50px 0;
  position: relative;
}

.section-header {
  max-width: 760px;
  margin: 0 auto 60px auto;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: rgba(var(--primary-rgb), 0.1);
  color: var(--primary);
  border: 1px solid rgba(var(--primary-rgb), 0.2);
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 16px;
}

.section-title {
  font-size: 2.5rem;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}

.section-desc {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ---------------- Buttons & Components ---------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: 0.95rem;
  padding: 10px 22px;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: #ffffff;
  box-shadow: 0 4px 14px rgba(var(--primary-rgb), 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(var(--primary-rgb), 0.5);
  background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary) 100%);
}

.btn-outline {
  background: transparent;
  border-color: var(--border-color);
  color: var(--text-primary);
}

.btn-outline:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: rgba(var(--primary-rgb), 0.05);
}

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

.btn-glass:hover {
  background: var(--bg-surface-elevated);
  border-color: var(--primary);
  transform: translateY(-2px);
}

.btn-lg {
  padding: 14px 28px;
  font-size: 1.05rem;
  border-radius: var(--radius-md);
}

.btn-sm {
  padding: 6px 14px;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
}

.btn-block {
  width: 100%;
}

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

.btn-icon:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.pulse-glow {
  position: relative;
}

.pulse-glow::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: inherit;
  background: linear-gradient(135deg, var(--primary), var(--secondary));
  z-index: -1;
  opacity: 0.4;
  filter: blur(8px);
  animation: pulse 2.5s infinite;
}

@keyframes pulse {

  0%,
  100% {
    opacity: 0.3;
    transform: scale(1);
  }

  50% {
    opacity: 0.7;
    transform: scale(1.02);
  }
}

/* ---------------- Header & Nav ---------------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  z-index: 1000;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: var(--bg-glass);
  border-bottom: 1px solid var(--border-color);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
  transition: background var(--transition-smooth), border-color var(--transition-smooth), box-shadow var(--transition-smooth);
}

.nav-container {
  width: 100%;
  max-width: none;
  padding: 0 36px;
  height: 72px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  position: relative;
  z-index: 1;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  justify-self: start;
}

.brand-info {
  display: flex;
  align-items: center;
  gap: 8px;
}

.brand-name {
  font-size: 1.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
}

.brand-accent {
  color: var(--primary);
}

.badge-version {
  font-size: 0.75rem;
  font-weight: 600;
  background: rgba(var(--primary-rgb), 0.15);
  color: var(--primary);
  padding: 2px 8px;
  border-radius: var(--radius-full);
  border: 1px solid rgba(var(--primary-rgb), 0.3);
}

/* Floating Pill Island Navigation (Mode 1) */
.nav-menu {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  justify-self: center;
  padding: 4px 6px;
  background: rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: var(--radius-full);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.25), inset 0 1px 0 rgba(255, 255, 255, 0.08);
  transition: all var(--transition-fast);
}

[data-theme="light"] .nav-menu {
  background: rgba(0, 0, 0, 0.04);
  border: 1px solid rgba(0, 0, 0, 0.08);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.06), inset 0 1px 0 rgba(255, 255, 255, 0.8);
}

.nav-link {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-secondary);
  position: relative;
  padding: 7px 16px;
  border-radius: var(--radius-full);
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

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

[data-theme="light"] .nav-link:hover {
  background: rgba(0, 0, 0, 0.05);
  color: var(--text-primary);
}

.nav-link.active {
  color: var(--primary);
  background: rgba(var(--primary-rgb), 0.14);
  box-shadow: 0 2px 10px rgba(var(--primary-rgb), 0.25);
}

/* Featured item with badge */
.nav-link-featured {
  position: relative;
}

.nav-badge-pill {
  font-size: 0.65rem;
  font-weight: 800;
  padding: 1px 6px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
  color: #ffffff;
  letter-spacing: 0.5px;
  box-shadow: 0 0 10px rgba(var(--primary-rgb), 0.5);
  animation: pulseBadge 2s infinite alternate;
}

@keyframes pulseBadge {
  0% { transform: scale(0.95); opacity: 0.85; }
  100% { transform: scale(1.05); opacity: 1; }
}

.nav-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
  justify-self: end;
}

.btn-github {
  display: flex;
  align-items: center;
  gap: 6px;
}

.star-pill {
  background: rgba(255, 255, 255, 0.1);
  padding: 2px 6px;
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
}

[data-theme="light"] .star-pill {
  background: rgba(0, 0, 0, 0.06);
}

/* Theme Icon logic */
[data-theme="dark"] .sun-icon {
  display: block;
}

[data-theme="dark"] .moon-icon {
  display: none;
}

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

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

.mobile-only {
  display: none;
}

/* ---------------- HERO SECTION ---------------- */
.hero-section {
  padding: 90px 0 50px 0;
  position: relative;
  text-align: center;
}

.hero-pill-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 18px;
  border-radius: var(--radius-full);
  background: var(--bg-glass-card);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border-color);
  font-size: 0.85rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.pill-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--primary);
  box-shadow: 0 0 8px var(--primary);
}

.hero-title {
  font-size: 3.6rem;
  letter-spacing: -0.03em;
  max-width: 960px;
  margin: 0 auto 24px auto;
  line-height: 1.15;
}

.hero-subtitle {
  font-size: 1.25rem;
  max-width: 780px;
  margin: 0 auto 40px auto;
  color: var(--text-secondary);
  line-height: 1.7;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 48px;
}

.badge-free {
  background: rgba(255, 255, 255, 0.25);
  font-size: 0.72rem;
  padding: 2px 6px;
  border-radius: 4px;
  margin-left: 4px;
}

.hero-badges {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 28px;
  margin-bottom: 60px;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.trust-item svg {
  color: var(--primary);
}

/* Browser Mockup Showcase */
.hero-mockup-wrapper {
  max-width: 1040px;
  margin: 0 auto;
  perspective: 1000px;
}

.browser-window {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  overflow: hidden;
  transition: transform var(--transition-smooth);
}

.browser-window:hover {
  transform: translateY(-4px);
}

.browser-header {
  background: var(--bg-surface-elevated);
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--border-color);
  gap: 16px;
}

.window-controls {
  display: flex;
  align-items: center;
  gap: 8px;
}

.control-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
}

.control-dot.red {
  background: #ff5f56;
}

.control-dot.yellow {
  background: #ffbd2e;
}

.control-dot.green {
  background: #27c93f;
}

.browser-address-bar {
  flex: 1;
  max-width: 580px;
  margin: 0 auto;
  background: var(--bg-main);
  border: 1px solid var(--border-color);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  font-size: 0.82rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.extension-active-pill {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.78rem;
  background: rgba(var(--primary-rgb), 0.15);
  color: var(--primary);
  border: 1px solid rgba(var(--primary-rgb), 0.3);
  padding: 4px 10px;
  border-radius: var(--radius-full);
  font-weight: 600;
}

.browser-body {
  position: relative;
  background: var(--code-bg);
  overflow: hidden;
}

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

.floating-badge {
  position: absolute;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 18px;
  background: var(--bg-glass-card);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  text-align: left;
  animation: float 4s ease-in-out infinite alternate;
}

.floating-badge.badge-top-right {
  top: 30px;
  right: 30px;
}

.floating-badge.badge-bottom-left {
  bottom: 30px;
  left: 30px;
  animation-delay: 2s;
}

.badge-icon {
  font-size: 1.5rem;
}

.badge-text strong {
  display: block;
  font-size: 0.88rem;
  color: var(--text-primary);
}

.badge-text span {
  font-size: 0.78rem;
  color: var(--primary);
}

@keyframes float {
  0% {
    transform: translateY(0px);
  }

  100% {
    transform: translateY(-10px);
  }
}

/* ---------------- PAIN POINTS SECTION ---------------- */
.pain-section {
  background: linear-gradient(180deg, transparent 0%, rgba(var(--primary-rgb), 0.02) 50%, transparent 100%);
}

.comparison-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.compare-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  transition: transform var(--transition-fast), border-color var(--transition-fast);
  position: relative;
}

.compare-card:hover {
  transform: translateY(-3px);
  border-color: rgba(var(--primary-rgb), 0.4);
}

/* 垂直居中分隔线：将左侧对比项与右侧对比项在 Header 与 Content 区域完整隔开 */
.compare-card::after {
  content: '';
  position: absolute;
  left: 50%;
  top: 20px;
  bottom: 20px;
  width: 1px;
  background: var(--border-color);
  transform: translateX(-50%);
  pointer-events: none;
  transition: background var(--transition-fast);
}

.compare-card:hover::after {
  background: rgba(var(--primary-rgb), 0.35);
}

.compare-header {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  align-items: center;
  margin-bottom: 20px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border-color);
}

.compare-badge {
  font-size: 0.82rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: var(--radius-full);
  display: inline-flex;
  align-items: center;
  width: fit-content;
}

.compare-badge.red {
  background: var(--danger-bg);
  color: var(--danger);
  border: 1px solid rgba(239, 68, 68, 0.3);
}

.compare-badge.green {
  background: var(--success-bg);
  color: var(--success);
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.compare-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.compare-content .side h4 {
  font-size: 1rem;
  margin-bottom: 8px;
}

.compare-content .side.before h4 {
  color: #f87171;
}

.compare-content .side.after h4 {
  color: var(--primary);
}

.compare-content .side p {
  font-size: 0.9rem;
  line-height: 1.6;
}

.compare-content .side code {
  background: var(--code-bg);
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
}

/* ---------------- FEATURES SECTION ---------------- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 28px;
  display: flex;
  flex-direction: column;
  transition: all var(--transition-smooth);
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--secondary));
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.feature-card:hover {
  transform: translateY(-5px);
  border-color: rgba(var(--primary-rgb), 0.3);
  box-shadow: var(--shadow-md);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.feature-icon-wrapper {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.color-cyan {
  background: rgba(6, 182, 212, 0.12);
  color: #06b6d4;
}

.color-blue {
  background: rgba(59, 130, 246, 0.12);
  color: #3b82f6;
}

.color-green {
  background: rgba(16, 185, 129, 0.12);
  color: #10b981;
}

.color-purple {
  background: rgba(139, 92, 246, 0.12);
  color: #8b5cf6;
}

.color-orange {
  background: rgba(249, 115, 22, 0.12);
  color: #f97316;
}

.color-pink {
  background: rgba(236, 72, 153, 0.12);
  color: #ec4899;
}

.feature-title {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 0;
  line-height: 1.35;
}

.feature-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 20px;
  flex: 1;
}

.feature-checklist {
  list-style: none;
  border-top: 1px solid var(--border-color);
  padding-top: 16px;
}

.feature-checklist li {
  font-size: 0.85rem;
  color: var(--text-muted);
  position: relative;
  padding-left: 20px;
  margin-bottom: 8px;
}

.feature-checklist li::before {
  content: '✓';
  position: absolute;
  left: 0;
  color: var(--primary);
  font-weight: 700;
}

/* ---------------- PLAYGROUND SECTION ---------------- */
.playground-section {
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.playground-presets {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 30px;
}

.presets-label {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-muted);
}

.preset-btn {
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  font-size: 0.88rem;
  font-weight: 600;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.preset-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.preset-btn.active {
  background: rgba(var(--primary-rgb), 0.15);
  border-color: var(--primary);
  color: var(--primary);
}

.playground-box {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  background: var(--bg-main);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.playground-col {
  display: flex;
  flex-direction: column;
  background: var(--bg-main);
  min-height: 420px;
}

.col-header {
  padding: 12px 20px;
  background: var(--bg-surface-elevated);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.col-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-primary);
}

.col-title .dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--secondary);
}

.col-title .dot.green {
  background: var(--primary);
}

.col-tag {
  font-size: 0.75rem;
  color: var(--text-muted);
}


.col-body {
  flex: 1;
  padding: 20px;
  overflow-y: auto;
  max-height: 380px;
}

.source-view {
  background: var(--bg-main);
  color: var(--text-primary);
  font-size: 0.9rem;
  line-height: 1.6;
  outline: none;
  min-height: 300px;
}

.source-view table {
  width: 100%;
  border-collapse: collapse;
  margin: 12px 0;
}

.source-view th,
.source-view td {
  border: 1px solid var(--border-color);
  padding: 8px 12px;
  font-size: 0.85rem;
}

.source-view pre {
  background: var(--code-bg);
  padding: 12px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.85rem;
  margin: 12px 0;
  white-space: pre-wrap;
}

.code-area {
  width: 100%;
  height: 100%;
  min-height: 320px;
  background: transparent;
  border: none;
  outline: none;
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--text-primary);
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
  overflow-x: auto;
  margin: 0;
  user-select: text;
}


.col-footer {
  padding: 12px 20px;
  background: var(--bg-surface-elevated);
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.stat-info {
  font-size: 0.82rem;
  color: var(--text-muted);
}

.token-summary {
  display: flex;
  align-items: center;
  gap: 12px;
}

.token-item {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.save-pill {
  background: rgba(var(--primary-rgb), 0.15);
  color: var(--primary);
  border: 1px solid rgba(var(--primary-rgb), 0.3);
  font-size: 0.78rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: var(--radius-full);
}

/* Middle Divider & Action Button */
.playground-divider {
  display: flex;
  align-items: center;
  justify-content: center;
  border-left: 1px solid var(--border-color);
  border-right: 1px solid var(--border-color);
  background: var(--bg-surface);
  padding: 16px 14px;
}

.btn-convert-trigger {
  display: inline-flex;
  flex-direction: row;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 42px;
  padding: 0 16px;
  border-radius: var(--radius-sm);
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: #ffffff;
  cursor: pointer;
  box-shadow: 0 4px 14px rgba(var(--primary-rgb), 0.35);
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-convert-trigger svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
  transition: transform var(--transition-fast);
}

.btn-convert-trigger span {
  font-size: 0.84rem;
  font-weight: 600;
  letter-spacing: 0.3px;
  margin-top: 0;
}

.btn-convert-trigger:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(var(--primary-rgb), 0.5);
  background: linear-gradient(135deg, var(--primary-light) 0%, var(--primary) 100%);
}

.btn-convert-trigger:hover svg {
  transform: translateX(2px);
}

.btn-convert-trigger:active {
  transform: translateY(0);
}

/* ---------------- SHOWCASE / GALLERY SECTION ---------------- */
.showcase-tabs {
  display: flex;
  align-items: center;
  justify-content: center;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 40px;
}

.showcase-tab-btn {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 12px 24px;
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 10px;
  transition: all var(--transition-fast);
}

.showcase-tab-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.showcase-tab-btn.active {
  background: var(--bg-surface-elevated);
  border-color: var(--primary);
  color: var(--primary);
  box-shadow: var(--shadow-sm);
}

.tab-num {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background: rgba(var(--primary-rgb), 0.15);
  color: var(--primary);
  padding: 2px 6px;
  border-radius: 4px;
}

.showcase-display {
  max-width: 1040px;
  margin: 0 auto;
}

.showcase-slide {
  display: none;
}

.showcase-slide.active {
  display: block;
  animation: fadeIn 0.4s ease-out;
}

.slide-image-box {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}

.slide-image-box img {
  width: 100%;
  height: auto;
  display: block;
  cursor: zoom-in;
  transition: transform var(--transition-smooth);
}

.slide-image-box img:hover {
  transform: scale(1.01);
}

.slide-caption {
  padding: 24px 30px;
  border-top: 1px solid var(--border-color);
  background: var(--bg-surface-elevated);
}

.slide-caption h4 {
  font-size: 1.15rem;
  margin-bottom: 6px;
}

.slide-caption p {
  font-size: 0.95rem;
  color: var(--text-secondary);
}

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

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

/* ---------------- INSTALL SECTION ---------------- */
.install-cards-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.install-card {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 44px 28px 28px 28px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all var(--transition-smooth);
}

.install-card:hover {
  transform: translateY(-5px);
  border-color: rgba(var(--primary-rgb), 0.4);
  box-shadow: var(--shadow-md);
}

.install-card.primary-card {
  border-color: var(--primary);
  background: linear-gradient(180deg, rgba(var(--primary-rgb), 0.05) 0%, var(--bg-surface) 100%);
  box-shadow: 0 0 25px rgba(var(--primary-rgb), 0.15);
}

.card-badge {
  position: absolute;
  top: 16px;
  right: 20px;
  font-size: 0.75rem;
  font-weight: 700;
  background: rgba(var(--primary-rgb), 0.15);
  color: var(--primary);
  padding: 3px 10px;
  border-radius: var(--radius-full);
}

.card-badge.secondary {
  background: rgba(var(--secondary-rgb), 0.15);
  color: var(--secondary);
}

.card-badge.tertiary {
  background: rgba(var(--accent-rgb), 0.15);
  color: var(--accent);
}

.install-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 12px;
}

.card-icon {
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.card-icon svg {
  width: 34px;
  height: 34px;
}

.install-card h3 {
  font-size: 1.18rem;
  font-weight: 700;
  line-height: 1.35;
  margin-bottom: 0;
  color: var(--text-primary);
}

.install-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 24px;
}

.install-steps {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 28px;
  flex: 1;
}

.step-row {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.step-num {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--bg-surface-elevated);
  border: 1px solid var(--border-color);
  color: var(--primary);
  font-size: 0.75rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 2px;
}

.step-row code {
  background: var(--code-bg);
  padding: 1px 4px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.8rem;
}

.code-terminal {
  background: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  margin-bottom: 24px;
  flex: 1;
}

.code-terminal pre {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--text-primary);
  white-space: pre-wrap;
}

.cmd-comment {
  color: var(--text-muted);
}

/* ---------------- FAQ SECTION ---------------- */
.faq-container {
  max-width: 840px;
}

.faq-accordion {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

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

.faq-item:hover {
  border-color: rgba(var(--primary-rgb), 0.3);
}

.faq-question {
  width: 100%;
  background: transparent;
  border: none;
  padding: 20px 24px;
  text-align: left;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
}

.faq-icon {
  color: var(--text-muted);
  transition: transform var(--transition-fast);
  flex-shrink: 0;
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s cubic-bezier(0, 1, 0, 1);
  padding: 0 24px;
}

.faq-answer p {
  padding-bottom: 20px;
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-secondary);
}

.faq-item.active .faq-icon {
  transform: rotate(180deg);
  color: var(--primary);
}

.faq-item.active .faq-answer {
  max-height: 500px;
  transition: max-height 0.35s ease-in-out;
}

/* ---------------- SPONSOR SECTION ---------------- */
.sponsor-container {
  max-width: 980px;
}

.sponsor-card {
  background: linear-gradient(135deg, var(--bg-surface-elevated) 0%, var(--bg-surface) 100%);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 48px;
  display: grid;
  grid-template-columns: 1.3fr 0.7fr;
  gap: 40px;
  align-items: center;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
}

.sponsor-card::after {
  content: '';
  position: absolute;
  bottom: -60px;
  right: -60px;
  width: 250px;
  height: 250px;
  background: radial-gradient(circle, rgba(var(--primary-rgb), 0.15) 0%, transparent 70%);
  pointer-events: none;
}

.sponsor-title {
  font-size: 2rem;
  margin-bottom: 16px;
}

.sponsor-desc {
  font-size: 1rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 28px;
}

.contact-methods {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.contact-item {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.95rem;
  color: var(--text-secondary);
}

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

.contact-item a:hover {
  color: var(--primary);
  text-decoration: underline;
}

.sponsor-qr-box {
  display: flex;
  justify-content: center;
}

.qr-frame {
  background: #ffffff;
  padding: 16px;
  border-radius: var(--radius-md);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.25);
  max-width: 240px;
  text-align: center;
}

.qr-img {
  width: 100%;
  height: auto;
  border-radius: 8px;
  display: block;
  cursor: zoom-in;
}

.qr-hint {
  margin-top: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  font-size: 0.78rem;
  font-weight: 600;
  color: #475569;
}

.qr-hint svg {
  color: var(--primary);
}

/* ---------------- FOOTER ---------------- */
.site-footer {
  border-top: 1px solid var(--border-color);
  background: var(--bg-main);
  padding: 60px 0 40px 0;
  color: var(--text-secondary);
}

.footer-container {
  display: grid;
  grid-template-columns: 1.2fr 2fr;
  gap: 48px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.2rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 12px;
}

.footer-tagline {
  font-size: 0.9rem;
  margin-bottom: 16px;
  max-width: 320px;
}

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

.footer-nav-groups {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.footer-nav-col h4 {
  font-size: 0.95rem;
  color: var(--text-primary);
  margin-bottom: 16px;
  font-weight: 700;
}

.footer-nav-col a {
  display: block;
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 10px;
}

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

/* ---------------- LIGHTBOX MODAL ---------------- */
.lightbox-modal {
  position: fixed;
  inset: 0;
  z-index: 9999;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
}

.lightbox-modal.active {
  opacity: 1;
  pointer-events: auto;
}

.lightbox-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.85);
  backdrop-filter: blur(8px);
}

.lightbox-content {
  position: relative;
  z-index: 10;
  max-width: 90vw;
  max-height: 90vh;
}

.lightbox-content img {
  max-width: 100%;
  max-height: 85vh;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  display: block;
}

.lightbox-close {
  position: absolute;
  top: -40px;
  right: -10px;
  background: none;
  border: none;
  color: #ffffff;
  font-size: 2.2rem;
  cursor: pointer;
  line-height: 1;
}

/* ---------------- RESPONSIVE BREAKPOINTS ---------------- */
@media (max-width: 1024px) {
  .hero-title {
    font-size: 2.8rem;
  }

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

  .install-cards-grid {
    grid-template-columns: 1fr;
  }

  .playground-box {
    grid-template-columns: 1fr;
    grid-template-rows: auto auto auto;
  }

  .playground-divider {
    border-top: 1px solid var(--border-color);
    border-bottom: 1px solid var(--border-color);
    border-left: none;
    border-right: none;
    padding: 16px;
  }

  .sponsor-card {
    grid-template-columns: 1fr;
    text-align: center;
  }

  .contact-methods {
    align-items: center;
  }
}

@media (max-width: 768px) {
  /* Mobile Responsive Atmosphere Glows */
  .glow-primary {
    top: -40px;
    left: 50%;
    transform: translateX(-50%);
    width: 280px;
    height: 280px;
    filter: blur(70px);
    opacity: 0.45;
  }

  .glow-secondary {
    top: 500px;
    right: -40px;
    width: 260px;
    height: 260px;
    filter: blur(60px);
    opacity: 0.35;
  }

  .grid-pattern {
    height: 700px;
    background-size: 24px 24px;
    mask-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.3) 0%, transparent 70%);
    -webkit-mask-image: linear-gradient(to bottom, rgba(0, 0, 0, 0.3) 0%, transparent 70%);
  }

  html {
    scroll-padding-top: 72px;
  }

  body {
    padding-top: 64px;
  }

  .nav-menu {
    display: none;
    border-radius: 0;
    border-left: none;
    border-right: none;
  }

  .mobile-only {
    display: flex;
  }

  .site-header .nav-container {
    height: 64px;
    padding: 0 16px;
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  /* Mobile header: hide logo text and non-essential buttons to prevent horizontal overflow */
  .brand-logo .brand-info {
    display: none;
  }

  .nav-actions .btn-github,
  .nav-actions .nav-cta {
    display: none;
  }

  .nav-actions {
    gap: 8px;
  }

  .btn-lang {
    padding: 0 8px;
    gap: 5px;
    height: 36px;
  }

  .btn-icon {
    width: 36px;
    height: 36px;
  }

  .hero-title {
    font-size: 2.1rem;
  }

  .hero-subtitle {
    font-size: 1.05rem;
  }

  .hero-cta-group {
    flex-direction: column;
    width: 100%;
  }

  .hero-cta-group .btn {
    width: 100%;
  }

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

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

  .footer-container {
    grid-template-columns: 1fr;
  }

  .footer-nav-groups {
    grid-template-columns: 1fr 1fr;
  }

  .floating-badge {
    display: none;
    /* Hide floating badges on narrow mobile to keep mockup clean */
  }

  .browser-address-bar {
    display: none;
  }
}

@media (max-width: 540px) {
  .compare-card {
    padding: 18px 14px;
  }

  .compare-card::after {
    top: 16px;
    bottom: 16px;
  }

  .compare-header,
  .compare-content {
    gap: 16px;
  }

  .compare-badge {
    font-size: 0.74rem;
    padding: 3px 8px;
    white-space: nowrap;
  }

  .compare-content .side h4 {
    font-size: 0.88rem;
    line-height: 1.35;
  }

  .compare-content .side p {
    font-size: 0.8rem;
    line-height: 1.5;
  }

  .install-card {
    padding: 42px 18px 22px 18px;
  }

  .install-header {
    gap: 10px;
    margin-bottom: 10px;
  }

  .card-icon svg {
    width: 28px;
    height: 28px;
  }

  .install-card h3 {
    font-size: 1.05rem;
  }
}

/* ---------------- LANGUAGE SELECTOR ---------------- */
.lang-selector {
  position: relative;
  display: inline-flex;
  align-items: center;
}

.btn-lang {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
  height: 38px;
  padding: 0 12px;
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  font-size: 0.84rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  box-shadow: var(--shadow-sm);
  user-select: none;
}

.lang-globe-icon {
  width: 16px;
  height: 16px;
  color: var(--text-secondary);
  transition: color var(--transition-fast);
  flex-shrink: 0;
}

.lang-cur-code {
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.2px;
  color: var(--text-primary);
  transition: color var(--transition-fast);
}

.lang-chevron {
  width: 12px;
  height: 12px;
  color: var(--text-muted);
  transition: transform var(--transition-fast), color var(--transition-fast);
  flex-shrink: 0;
}

.btn-lang:hover {
  border-color: var(--primary);
  color: var(--primary);
  background: rgba(var(--primary-rgb), 0.08);
}

.btn-lang:hover .lang-globe-icon,
.btn-lang:hover .lang-cur-code,
.btn-lang:hover .lang-chevron {
  color: var(--primary);
}

.lang-selector.open .btn-lang {
  border-color: var(--primary);
  background: rgba(var(--primary-rgb), 0.09);
  color: var(--primary);
  box-shadow: 0 0 0 3px rgba(var(--primary-rgb), 0.15);
}

.lang-selector.open .lang-globe-icon,
.lang-selector.open .lang-cur-code,
.lang-selector.open .lang-chevron {
  color: var(--primary);
}

.lang-selector.open .lang-chevron {
  transform: rotate(180deg);
}

.lang-dropdown {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  min-width: 155px;
  background: var(--bg-surface-elevated);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 6px;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-8px) scale(0.96);
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  z-index: 1000;
  pointer-events: none;
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.lang-selector.open .lang-dropdown,
.lang-dropdown.open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
  pointer-events: auto;
}

.lang-option {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 6px;
  border: none;
  background: transparent;
  color: var(--text-primary);
  font-size: 0.83rem;
  font-weight: 500;
  cursor: pointer;
  text-align: left;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.lang-option:hover {
  background: rgba(var(--primary-rgb), 0.1);
  color: var(--primary);
}

.lang-option.active {
  background: rgba(var(--primary-rgb), 0.15);
  color: var(--primary);
  font-weight: 700;
}

/* Light Theme Enhancements for Lang Selector */
[data-theme="light"] .btn-lang {
  background: #ffffff;
  border-color: rgba(0, 0, 0, 0.12);
  color: var(--text-primary);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.05);
}

[data-theme="light"] .btn-lang:hover {
  background: rgba(var(--primary-rgb), 0.06);
  border-color: var(--primary);
}

[data-theme="light"] .lang-dropdown {
  background: #ffffff;
  border-color: rgba(0, 0, 0, 0.1);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.1);
}

[data-theme="light"] .lang-option {
  color: #334155;
}

[data-theme="light"] .lang-option:hover {
  background: rgba(var(--primary-rgb), 0.08);
  color: var(--primary);
}

[data-theme="light"] .lang-option.active {
  background: rgba(var(--primary-rgb), 0.12);
  color: var(--primary);
}

/* ---------------- BACK TO TOP BUTTON ---------------- */
.back-to-top {
  position: fixed;
  right: 28px;
  bottom: 32px;
  z-index: 999;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: var(--bg-surface-elevated);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.28);
  opacity: 0;
  visibility: hidden;
  transform: translateY(18px) scale(0.9);
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0) scale(1);
}

.back-to-top:hover {
  background: var(--primary);
  color: #ffffff;
  border-color: var(--primary);
  transform: translateY(-4px) scale(1.05);
  box-shadow: 0 10px 24px rgba(var(--primary-rgb), 0.45);
}

.back-to-top:active {
  transform: translateY(-1px) scale(0.98);
}

@media (max-width: 768px) {
  .back-to-top {
    right: 18px;
    bottom: 24px;
    width: 42px;
    height: 42px;
  }
}