/* ============================================
   PS Tutorial Website - Global Styles
   Colorful Glassmorphism Light Theme
   ============================================ */

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

/* ---------- CSS Custom Properties ---------- */
:root {
  /* Colors */
  --color-primary: #6366f1;
  --color-primary-light: #818cf8;
  --color-primary-dark: #4f46e5;
  --color-secondary: #a855f7;
  --color-secondary-light: #c084fc;
  --color-accent: #06b6d4;
  --color-accent-warm: #f59e0b;

  --gradient-primary: linear-gradient(135deg, #6366f1, #a855f7);
  --gradient-hero: linear-gradient(135deg, rgba(238, 242, 255, 0.7) 0%, rgba(224, 231, 255, 0.5) 30%, rgba(245, 243, 255, 0.5) 60%, rgba(237, 233, 254, 0.6) 100%);
  --gradient-card: linear-gradient(135deg, rgba(255, 255, 255, 0.65), rgba(248, 250, 252, 0.55));
  --gradient-accent: linear-gradient(135deg, #06b6d4, #6366f1, #a855f7);
  --gradient-text: linear-gradient(135deg, #6366f1, #a855f7);

  /* Backgrounds – Glassmorphism */
  --bg-body: linear-gradient(135deg, #e0e7ff 0%, #f0e6ff 25%, #e0f2fe 50%, #fce7f3 75%, #ede9fe 100%);
  --bg-card: rgba(255, 255, 255, 0.55);
  --bg-card-hover: rgba(255, 255, 255, 0.72);
  --bg-section-alt: rgba(248, 250, 252, 0.45);
  --bg-nav: rgba(255, 255, 255, 0.6);
  --bg-code: rgba(241, 245, 249, 0.7);
  --bg-tag: rgba(238, 242, 255, 0.7);

  /* Glass */
  --glass-blur: blur(18px);
  --glass-border: 1px solid rgba(255, 255, 255, 0.45);
  --glass-shadow: 0 8px 32px rgba(99, 102, 241, 0.08);

  /* Text */
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-tertiary: #94a3b8;
  --text-inverse: #ffffff;
  --text-link: #6366f1;

  /* Borders */
  --border-light: rgba(226, 232, 240, 0.6);
  --border-medium: rgba(203, 213, 225, 0.6);
  --border-focus: #6366f1;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(99, 102, 241, 0.04), 0 1px 2px rgba(0, 0, 0, 0.03);
  --shadow-md: 0 4px 16px rgba(99, 102, 241, 0.08), 0 2px 4px rgba(0, 0, 0, 0.03);
  --shadow-lg: 0 10px 30px rgba(99, 102, 241, 0.1), 0 4px 8px rgba(0, 0, 0, 0.04);
  --shadow-xl: 0 20px 50px rgba(99, 102, 241, 0.12), 0 8px 16px rgba(0, 0, 0, 0.05);
  --shadow-glow: 0 0 40px rgba(99, 102, 241, 0.18);
  --shadow-card-hover: 0 12px 40px rgba(99, 102, 241, 0.15), 0 4px 12px rgba(168, 85, 247, 0.08);

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  /* Border Radius */
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-xl: 28px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-spring: 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);

  /* Z-index */
  --z-bg: -1;
  --z-nav: 1000;
  --z-modal: 2000;
  --z-tooltip: 3000;

  /* Typography */
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-body);
  background-attachment: fixed;
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  position: relative;
}

/* ---------- Three.js Canvas Background ---------- */
#bg-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: var(--z-bg);
  pointer-events: none;
}

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

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

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

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

ul,
ol {
  list-style: none;
}

/* ---------- Navigation ---------- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: var(--z-nav);
  background: var(--bg-nav);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-bottom: var(--glass-border);
  transition: all var(--transition-base);
}

.navbar.scrolled {
  box-shadow: var(--shadow-md);
  background: rgba(255, 255, 255, 0.75);
}

.nav-container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

.nav-logo {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-weight: 800;
  font-size: 1.3rem;
  color: var(--text-primary);
  text-decoration: none;
}

.nav-logo .logo-icon {
  width: 38px;
  height: 38px;
  background: var(--gradient-primary);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 900;
  font-size: 0.85rem;
  letter-spacing: -0.5px;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.nav-link {
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: all var(--transition-base);
  position: relative;
  text-decoration: none;
}

.nav-link:hover {
  color: var(--color-primary);
  background: var(--bg-tag);
}

.nav-link.active {
  color: var(--color-primary);
  background: var(--bg-tag);
  font-weight: 600;
}

.nav-hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  padding: var(--space-2);
  cursor: pointer;
}

.nav-hamburger span {
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--transition-base);
}

/* Mobile nav */
@media (max-width: 768px) {
  .nav-hamburger {
    display: flex;
  }

  .nav-links {
    position: fixed;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--bg-card);
    flex-direction: column;
    padding: var(--space-4);
    border-bottom: 1px solid var(--border-light);
    box-shadow: var(--shadow-lg);
    transform: translateY(-120%);
    opacity: 0;
    transition: all var(--transition-base);
  }

  .nav-links.open {
    transform: translateY(0);
    opacity: 1;
  }

  .nav-link {
    width: 100%;
    text-align: center;
    padding: var(--space-3) var(--space-4);
  }
}

/* ---------- Hero Section ---------- */
.hero {
  position: relative;
  min-height: 85vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--gradient-hero);
  backdrop-filter: blur(2px);
  padding: 120px var(--space-6) var(--space-16);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.12) 0%, transparent 70%);
  border-radius: 50%;
  animation: float-slow 15s ease-in-out infinite;
}

.hero::after {
  content: '';
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(168, 85, 247, 0.1) 0%, transparent 70%);
  border-radius: 50%;
  animation: float-slow 12s ease-in-out infinite reverse;
}

.hero-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 800px;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: var(--space-8);
  box-shadow: var(--shadow-sm);
  animation: fadeInDown 0.8s ease;
}

.hero-badge .badge-dot {
  width: 8px;
  height: 8px;
  background: #10B981;
  border-radius: 50%;
  animation: pulse-dot 2s ease-in-out infinite;
}

.hero h1 {
  font-size: clamp(2.5rem, 6vw, 4rem);
  font-weight: 900;
  line-height: 1.1;
  margin-bottom: var(--space-6);
  color: var(--text-primary);
  animation: fadeInUp 0.8s ease 0.1s both;
}

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

.hero-description {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto var(--space-10);
  line-height: 1.8;
  animation: fadeInUp 0.8s ease 0.2s both;
}

.hero-actions {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeInUp 0.8s ease 0.3s both;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius-md);
  font-size: 0.95rem;
  font-weight: 600;
  transition: all var(--transition-base);
  text-decoration: none;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--gradient-primary);
  color: var(--text-inverse);
  box-shadow: 0 4px 15px rgba(37, 99, 235, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(37, 99, 235, 0.4);
  color: var(--text-inverse);
}

.btn-secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: 0.85rem;
}

/* ---------- Sections ---------- */
.section {
  padding: var(--space-20) var(--space-6);
}

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

.container {
  max-width: 1280px;
  margin: 0 auto;
}

.section-header {
  text-align: center;
  margin-bottom: var(--space-12);
}

.section-header .section-label {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-4);
  background: var(--bg-tag);
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-primary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: var(--space-4);
}

.section-header h2 {
  font-size: clamp(1.8rem, 4vw, 2.5rem);
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
  line-height: 1.2;
}

.section-header p {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ---------- Cards ---------- */
.card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-8);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
  box-shadow: var(--glass-shadow);
}

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

.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-card-hover);
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.6);
}

.card:hover::before {
  transform: scaleX(1);
}

.card-icon {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: var(--space-5);
  position: relative;
}

.card-icon.blue {
  background: #EFF6FF;
  color: #2563EB;
}

.card-icon.purple {
  background: #F5F3FF;
  color: #7C3AED;
}

.card-icon.cyan {
  background: #ECFEFF;
  color: #06B6D4;
}

.card-icon.amber {
  background: #FFFBEB;
  color: #F59E0B;
}

.card-icon.green {
  background: #F0FDF4;
  color: #10B981;
}

.card-icon.rose {
  background: #FFF1F2;
  color: #F43F5E;
}

.card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: var(--space-3);
  color: var(--text-primary);
}

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

.card-link {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  margin-top: var(--space-4);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary);
  transition: gap var(--transition-base);
}

.card-link:hover {
  gap: var(--space-3);
}

/* ---------- Feature Grid ---------- */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
}

/* ---------- Stats ---------- */
.stats-bar {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-6);
  padding: var(--space-10) var(--space-8);
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-radius: var(--radius-xl);
  box-shadow: var(--glass-shadow);
  border: var(--glass-border);
  position: relative;
  overflow: hidden;
}

.stats-bar::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-accent);
}

.stat-item {
  text-align: center;
  padding: var(--space-2);
}

.stat-number {
  font-size: 2.5rem;
  font-weight: 900;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1.1;
  margin-bottom: var(--space-2);
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* ---------- Tags ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  padding: var(--space-1) var(--space-3);
  background: var(--bg-tag);
  border-radius: var(--radius-full);
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--color-primary);
  border: 1px solid transparent;
  transition: all var(--transition-fast);
  cursor: pointer;
}

.tag:hover,
.tag.active {
  background: var(--color-primary);
  color: var(--text-inverse);
  border-color: var(--color-primary);
}

.tag-group {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

/* ---------- Search ---------- */
.search-box {
  position: relative;
  max-width: 500px;
}

.search-box input {
  width: 100%;
  padding: var(--space-3) var(--space-4) var(--space-3) 48px;
  border: 2px solid var(--border-light);
  border-radius: var(--radius-lg);
  font-family: var(--font-sans);
  font-size: 0.95rem;
  background: var(--bg-card);
  color: var(--text-primary);
  transition: all var(--transition-base);
  outline: none;
}

.search-box input::placeholder {
  color: var(--text-tertiary);
}

.search-box input:focus {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.1);
}

.search-box .search-icon {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-tertiary);
  font-size: 1rem;
  pointer-events: none;
}

/* ---------- Keyboard Key Visual ---------- */
.key {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 36px;
  height: 36px;
  padding: 0 var(--space-3);
  background: linear-gradient(180deg, #FFFFFF 0%, #F1F5F9 100%);
  border: 1px solid var(--border-medium);
  border-bottom-width: 3px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-primary);
  box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
  white-space: nowrap;
}

.key-combo {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.key-plus {
  font-size: 0.75rem;
  color: var(--text-tertiary);
  font-weight: 400;
}

/* ---------- Tabs ---------- */
.tabs {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-8);
}

.tab-btn {
  padding: var(--space-2) var(--space-5);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 500;
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border-light);
  transition: all var(--transition-base);
  cursor: pointer;
}

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

.tab-btn.active {
  background: var(--color-primary);
  color: var(--text-inverse);
  border-color: var(--color-primary);
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
}

/* ---------- Toggle Switch ---------- */
.toggle-wrapper {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  font-size: 0.9rem;
  font-weight: 500;
}

.toggle-label {
  color: var(--text-secondary);
  transition: color var(--transition-fast);
}

.toggle-label.active {
  color: var(--color-primary);
  font-weight: 600;
}

.toggle {
  width: 52px;
  height: 28px;
  background: var(--border-medium);
  border-radius: 14px;
  position: relative;
  cursor: pointer;
  transition: background var(--transition-base);
  border: none;
}

.toggle.active {
  background: var(--color-primary);
}

.toggle::after {
  content: '';
  position: absolute;
  width: 22px;
  height: 22px;
  background: white;
  border-radius: 50%;
  top: 3px;
  left: 3px;
  transition: transform var(--transition-base);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.15);
}

.toggle.active::after {
  transform: translateX(24px);
}

/* ---------- Page Header (with banner) ---------- */
.page-header {
  padding: 100px var(--space-6) 0;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.page-header .banner-img {
  width: 100%;
  max-width: 1280px;
  margin: var(--space-8) auto 0;
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  object-fit: cover;
  max-height: 320px;
}

.page-header h1 {
  font-size: clamp(2rem, 4vw, 2.8rem);
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
}

.page-header p {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 600px;
  margin: 0 auto;
  line-height: 1.7;
}

/* ---------- Shortcut Card ---------- */
.shortcut-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-5);
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-md);
  transition: all var(--transition-base);
  gap: var(--space-4);
}

.shortcut-card:hover {
  border-color: rgba(99, 102, 241, 0.3);
  box-shadow: var(--shadow-md);
  transform: translateX(4px);
  background: var(--bg-card-hover);
}

.shortcut-info {
  flex: 1;
}

.shortcut-name {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-primary);
  margin-bottom: 2px;
}

.shortcut-desc {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

/* ---------- Tool Card ---------- */
.tool-card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: all var(--transition-base);
  cursor: pointer;
  position: relative;
  overflow: hidden;
  box-shadow: var(--glass-shadow);
}

.tool-card::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-primary);
  transform: scaleX(0);
  transition: transform var(--transition-base);
}

.tool-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-card-hover);
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.6);
}

.tool-card:hover::after {
  transform: scaleX(1);
}

.tool-card .tool-icon {
  font-size: 2rem;
  margin-bottom: var(--space-4);
}

.tool-card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: var(--space-2);
  color: var(--text-primary);
}

.tool-card .tool-shortcut {
  margin-bottom: var(--space-3);
}

.tool-card p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

.tool-detail {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.tool-card.expanded .tool-detail {
  max-height: 500px;
}

.tool-detail-content {
  padding-top: var(--space-4);
  margin-top: var(--space-4);
  border-top: 1px solid var(--border-light);
}

.tool-detail-content h4 {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.tool-detail-content ul {
  list-style: none;
}

.tool-detail-content li {
  font-size: 0.83rem;
  color: var(--text-secondary);
  padding: var(--space-1) 0;
  padding-left: var(--space-4);
  position: relative;
}

.tool-detail-content li::before {
  content: '→';
  position: absolute;
  left: 0;
  color: var(--color-primary);
}

/* ---------- Tip Card ---------- */
.tip-card {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition-base);
  box-shadow: var(--glass-shadow);
}

.tip-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-card-hover);
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.6);
}

.tip-card-header {
  padding: var(--space-5) var(--space-6);
  display: flex;
  align-items: flex-start;
  gap: var(--space-4);
  cursor: pointer;
}

.tip-card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.3rem;
  flex-shrink: 0;
}

.tip-card-meta {
  flex: 1;
}

.tip-card-meta h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.tip-card-meta .tip-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.tip-difficulty {
  font-size: 0.78rem;
  color: var(--text-tertiary);
}

.tip-steps {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.tip-card.expanded .tip-steps {
  max-height: 2000px;
}

.tip-steps-content {
  padding: 0 var(--space-6) var(--space-6);
  border-top: 1px solid var(--border-light);
}

.step-item {
  display: flex;
  gap: var(--space-4);
  padding: var(--space-4) 0;
  border-bottom: 1px solid var(--border-light);
}

.step-item:last-child {
  border-bottom: none;
}

.step-number {
  width: 32px;
  height: 32px;
  background: var(--bg-tag);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--color-primary);
  flex-shrink: 0;
}

.step-text {
  flex: 1;
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  padding-top: 4px;
}

/* ---------- Learning Path ---------- */
.timeline {
  position: relative;
  max-width: 800px;
  margin: 0 auto;
}

.timeline::before {
  content: '';
  position: absolute;
  left: 28px;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--gradient-primary);
  border-radius: 3px;
}

.timeline-item {
  position: relative;
  padding-left: 76px;
  padding-bottom: var(--space-10);
}

.timeline-item:last-child {
  padding-bottom: 0;
}

.timeline-dot {
  position: absolute;
  left: 16px;
  top: 6px;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  background: var(--bg-card);
  border: 3px solid var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2;
  transition: all var(--transition-base);
}

.timeline-dot::after {
  content: '';
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--color-primary);
}

.timeline-item:hover .timeline-dot {
  transform: scale(1.15);
  box-shadow: 0 0 0 6px rgba(37, 99, 235, 0.15);
}

.timeline-content {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  transition: all var(--transition-base);
  cursor: pointer;
  box-shadow: var(--glass-shadow);
}

.timeline-content:hover {
  box-shadow: var(--shadow-lg);
  background: var(--bg-card-hover);
  border-color: rgba(255, 255, 255, 0.6);
}

.timeline-phase {
  display: inline-flex;
  padding: var(--space-1) var(--space-3);
  background: var(--bg-tag);
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--color-primary);
  margin-bottom: var(--space-3);
}

.timeline-content h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.timeline-content p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-3);
}

.timeline-skills {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.timeline-detail {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

.timeline-content.expanded .timeline-detail {
  max-height: 1000px;
}

.timeline-detail-inner {
  padding-top: var(--space-4);
  margin-top: var(--space-3);
  border-top: 1px solid var(--border-light);
}

.timeline-detail-inner h4 {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-2);
  margin-top: var(--space-3);
}

.timeline-detail-inner h4:first-child {
  margin-top: 0;
}

.timeline-detail-inner ul {
  list-style: none;
}

.timeline-detail-inner li {
  font-size: 0.83rem;
  color: var(--text-secondary);
  padding: var(--space-1) 0;
  padding-left: var(--space-5);
  position: relative;
}

.timeline-detail-inner li::before {
  content: '✦';
  position: absolute;
  left: 0;
  color: var(--color-primary);
  font-size: 0.7rem;
}

/* ---------- Virtual Keyboard ---------- */
.virtual-keyboard {
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  box-shadow: var(--glass-shadow);
  margin-bottom: var(--space-8);
  overflow-x: auto;
}

.keyboard-row {
  display: flex;
  gap: 6px;
  margin-bottom: 6px;
  justify-content: center;
}

.keyboard-row:last-child {
  margin-bottom: 0;
}

.kb-key {
  min-width: 46px;
  height: 46px;
  background: linear-gradient(180deg, #FAFBFC 0%, #EFF1F3 100%);
  border: 1px solid var(--border-medium);
  border-bottom-width: 3px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-sans);
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-primary);
  transition: all var(--transition-base);
  cursor: default;
  user-select: none;
  flex-shrink: 0;
}

.kb-key.highlighted {
  background: linear-gradient(180deg, #3B82F6, #2563EB);
  color: white;
  border-color: #1D4ED8;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.35);
  transform: translateY(-2px);
}

.kb-key.w-tab {
  min-width: 70px;
}

.kb-key.w-caps {
  min-width: 80px;
}

.kb-key.w-shift {
  min-width: 110px;
}

.kb-key.w-ctrl {
  min-width: 65px;
}

.kb-key.w-space {
  min-width: 280px;
}

.kb-key.w-backspace {
  min-width: 90px;
}

.kb-key.w-enter {
  min-width: 100px;
}

/* ---------- Footer ---------- */
.footer {
  background: rgba(255, 255, 255, 0.5);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border-top: var(--glass-border);
  padding: var(--space-12) var(--space-6) var(--space-8);
}

.footer-content {
  max-width: 1280px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--space-10);
}

.footer-brand {
  max-width: 300px;
}

.footer-brand .nav-logo {
  margin-bottom: var(--space-4);
}

.footer-brand p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.footer-col h4 {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-4);
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.footer-col a {
  display: block;
  font-size: 0.88rem;
  color: var(--text-secondary);
  padding: var(--space-1) 0;
  transition: color var(--transition-fast);
}

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

.footer-bottom {
  max-width: 1280px;
  margin: var(--space-8) auto 0;
  padding-top: var(--space-6);
  border-top: 1px solid var(--border-light);
  text-align: center;
  font-size: 0.82rem;
  color: var(--text-tertiary);
}

@media (max-width: 768px) {
  .footer-content {
    grid-template-columns: 1fr;
    gap: var(--space-8);
  }
}

/* ---------- Scroll Animations ---------- */
.fade-in {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

.fade-in-left {
  opacity: 0;
  transform: translateX(-30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-left.visible {
  opacity: 1;
  transform: translateX(0);
}

.fade-in-right {
  opacity: 0;
  transform: translateX(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in-right.visible {
  opacity: 1;
  transform: translateX(0);
}

/* ---------- Keyframes ---------- */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }

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

@keyframes fadeInDown {
  from {
    opacity: 0;
    transform: translateY(-20px);
  }

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

@keyframes float-slow {

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

  50% {
    transform: translate(-20px, 20px);
  }
}

@keyframes pulse-dot {

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

  50% {
    opacity: 0.7;
    transform: scale(1.3);
  }
}

@keyframes countUp {
  from {
    opacity: 0;
    transform: translateY(10px);
  }

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

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

  100% {
    background-position: 200% center;
  }
}

@keyframes slideInRight {
  from {
    opacity: 0;
    transform: translateX(20px);
  }

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

/* ---------- Scroll Bar ---------- */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

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

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

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

/* ---------- Selection ---------- */
::selection {
  background: rgba(37, 99, 235, 0.15);
  color: var(--color-primary-dark);
}

/* ---------- Utility ---------- */
.text-center {
  text-align: center;
}

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

.mt-4 {
  margin-top: var(--space-4);
}

.mt-8 {
  margin-top: var(--space-8);
}

.mb-4 {
  margin-bottom: var(--space-4);
}

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

.gap-4 {
  gap: var(--space-4);
}

.flex {
  display: flex;
}

.flex-wrap {
  flex-wrap: wrap;
}

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

.justify-between {
  justify-content: space-between;
}

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

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-6);
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-6);
}

@media (max-width: 768px) {

  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }

  .hero {
    min-height: 70vh;
    padding-top: 100px;
  }

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

  .virtual-keyboard {
    display: none;
  }
}

/* ---------- No Results ---------- */
.no-results {
  text-align: center;
  padding: var(--space-16) var(--space-6);
  color: var(--text-tertiary);
}

.no-results .no-results-icon {
  font-size: 3rem;
  margin-bottom: var(--space-4);
}

.no-results p {
  font-size: 1rem;
}

/* ---------- Back to top ---------- */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: var(--gradient-primary);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  box-shadow: 0 4px 15px rgba(37, 99, 235, 0.3);
  cursor: pointer;
  opacity: 0;
  pointer-events: none;
  transition: all var(--transition-base);
  z-index: 100;
  border: none;
}

.back-to-top.visible {
  opacity: 1;
  pointer-events: auto;
}

.back-to-top:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(37, 99, 235, 0.4);
}

/* ---------- Shortcut Grid ---------- */
.shortcut-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: var(--space-3);
}

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

/* ---------- Tool Grid ---------- */
.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: var(--space-5);
}

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

/* ---------- Tip Grid ---------- */
.tip-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(400px, 1fr));
  gap: var(--space-5);
}

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

/* ---------- Controls bar---------- */
.controls-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-4);
  margin-bottom: var(--space-6);
  padding: var(--space-4) var(--space-5);
  background: var(--bg-card);
  backdrop-filter: var(--glass-blur);
  -webkit-backdrop-filter: var(--glass-blur);
  border: var(--glass-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--glass-shadow);
}

.controls-bar .search-box {
  flex: 1;
  min-width: 200px;
}

.result-count {
  font-size: 0.85rem;
  color: var(--text-tertiary);
  font-weight: 500;
}