/* ============================================================
   知源学堂 zylearn · Digital Apothecary
   CSS Custom Properties & Global Styles
   ============================================================ */

:root {
  --color-bg: #F8F5F0;
  --color-bg-alt: #ECE8E2;
  --color-surface: #FDFCFA;
  --color-primary: #2C5F45;
  --color-primary-glow: #3A7A5C;
  --color-primary-dim: rgba(44, 95, 69, 0.08);
  --color-accent: #8C5A3E;
  --color-accent-glow: #A67050;
  --color-accent-dim: rgba(140, 90, 62, 0.08);
  --color-card-bg: rgba(253, 252, 250, 0.8);
  --color-card-bg-hover: rgba(248, 245, 240, 0.95);
  --color-card-border: rgba(140, 90, 62, 0.12);
  --color-card-border-hover: rgba(44, 95, 69, 0.3);
  --color-text: #222825;
  --color-text-secondary: #595F5C;
  --color-text-muted: #A09A8E;
  --color-border-subtle: rgba(44, 95, 69, 0.07);
  --color-border-medium: rgba(44, 95, 69, 0.12);
  --font-heading: 'Noto Serif SC', serif;
  --font-mono: 'JetBrains Mono', monospace;
  --font-body: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans SC', sans-serif;
  --transition-base: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --container-max: 1200px;
  --container-padding: clamp(1rem, 5vw, 3rem);
}

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

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

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

body {
  font-family: var(--font-body);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  overflow-x: hidden;
  min-height: 100vh;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

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

/* ============================================================
   Background Layers
   ============================================================ */

#particle-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
}

.bg-grid {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(var(--color-border-subtle) 1px, transparent 1px),
    linear-gradient(90deg, var(--color-border-subtle) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, black 30%, transparent 70%);
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 40%, black 30%, transparent 70%);
}

.bg-radial {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 60% 50% at 50% 40%, rgba(44, 95, 69, 0.06) 0%, transparent 55%),
    radial-gradient(ellipse 35% 35% at 75% 15%, rgba(140, 90, 62, 0.04) 0%, transparent 50%),
    radial-gradient(ellipse 45% 25% at 15% 80%, rgba(44, 95, 69, 0.03) 0%, transparent 50%),
    radial-gradient(ellipse 30% 20% at 85% 85%, rgba(140, 90, 62, 0.02) 0%, transparent 40%);
}

main {
  position: relative;
  z-index: 1;
}

/* ============================================================
   Section Container
   ============================================================ */

.section-container {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 var(--container-padding);
}

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto clamp(3rem, 6vw, 5rem);
}

.section-title {
  font-family: var(--font-heading);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  color: var(--color-text);
  letter-spacing: 0.04em;
  margin-bottom: 1rem;
}

.section-line {
  width: 60px;
  height: 2px;
  margin: 0 auto 1.5rem;
  background: linear-gradient(90deg, transparent, var(--color-accent), transparent);
  border-radius: 1px;
}

.section-subtitle {
  font-family: var(--font-body);
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  letter-spacing: 0.02em;
  font-weight: 400;
}

/* ============================================================
   HERO SECTION
   ============================================================ */

.hero {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 2rem var(--container-padding);
  text-align: center;
}

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

/* Badge */

.hero-logo {
  width: clamp(80px, 12vw, 120px);
  height: clamp(80px, 12vw, 120px);
  margin: 0 auto 2rem;
  animation: logo-float 6s ease-in-out infinite;
}

.hero-logo svg {
  width: 100%;
  height: 100%;
}

@keyframes logo-float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-8px); }
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1rem;
  background: var(--color-primary-dim);
  border: 1px solid var(--color-card-border);
  border-radius: 100px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--color-primary);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.badge-dot {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-primary);
  box-shadow: 0 0 8px var(--color-primary-glow);
  animation: badge-pulse 2s ease-in-out infinite;
}

@keyframes badge-pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.6; transform: scale(0.9); }
}

/* Title */

.hero-title {
  font-family: var(--font-heading);
  font-size: clamp(3.5rem, 10vw, 7rem);
  font-weight: 900;
  line-height: 1.1;
  margin-bottom: 1rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-glow) 30%, var(--color-accent-glow) 70%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 30px rgba(44, 95, 69, 0.08));
}

.title-char {
  display: inline-block;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 20px rgba(44, 95, 69, 0.15));
}

/* Subtitle */

.hero-subtitle {
  font-family: var(--font-mono);
  font-size: clamp(1rem, 1.8vw, 1.3rem);
  color: var(--color-primary);
  letter-spacing: 0.06em;
  margin-bottom: 1.5rem;
  text-shadow: 0 0 30px rgba(44, 95, 69, 0.15);
}

/* Description */

.hero-desc {
  font-size: clamp(0.95rem, 1.5vw, 1.15rem);
  color: var(--color-text-secondary);
  line-height: 1.8;
  max-width: 600px;
  margin: 0 auto 2.5rem;
}

/* CTA Buttons */

.hero-cta {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.85rem 2rem;
  border-radius: 100px;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  transition: all var(--transition-base);
  cursor: pointer;
  position: relative;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-glow) 100%);
  color: var(--color-bg);
  box-shadow:
    0 4px 20px rgba(44, 95, 69, 0.2),
    0 0 40px rgba(44, 95, 69, 0.06);
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.1);
}

.btn-primary:hover {
  box-shadow: 0 6px 30px rgba(44, 95, 69, 0.3);
  transform: translateY(-2px);
}

.btn-outline {
  background: transparent;
  color: var(--color-text);
  border: 1px solid rgba(237, 242, 247, 0.2);
  backdrop-filter: blur(4px);
}

.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  box-shadow: 0 0 20px rgba(44, 95, 69, 0.1);
  transform: translateY(-2px);
}

.btn-icon {
  flex-shrink: 0;
}

/* Scroll Indicator */

.hero-scroll-indicator {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.6rem;
  z-index: 2;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(-6px); }
}

.scroll-text {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--color-text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.scroll-line {
  width: 1px;
  height: 40px;
  background: linear-gradient(to bottom, var(--color-text-muted), transparent);
  border-radius: 1px;
}

/* Stagger Animation */

.stagger-item {
  opacity: 0;
  transform: translateY(30px);
  animation: stagger-in 0.7s cubic-bezier(0.4, 0, 0.2, 1) forwards;
}

.stagger-item:nth-child(1) { animation-delay: 0.1s; }
.stagger-item:nth-child(2) { animation-delay: 0.25s; }
.stagger-item:nth-child(3) { animation-delay: 0.4s; }
.stagger-item:nth-child(4) { animation-delay: 0.55s; }
.stagger-item:nth-child(5) { animation-delay: 0.7s; }

@keyframes stagger-in {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ============================================================
   FEATURES SECTION
   ============================================================ */

.features {
  padding: clamp(4rem, 10vw, 8rem) 0;
  position: relative;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(1.2rem, 2vw, 1.8rem);
}

/* Feature Card */

.feature-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  padding: clamp(1.8rem, 3vw, 2.5rem);
  backdrop-filter: blur(24px) saturate(180%);
  -webkit-backdrop-filter: blur(24px) saturate(180%);
  transition:
    transform var(--transition-slow),
    box-shadow var(--transition-slow),
    border-color var(--transition-slow),
    background var(--transition-slow);
  cursor: default;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(ellipse at 50% 0%, rgba(44, 95, 69, 0.1), transparent 75%);
  opacity: 0;
  transition: opacity var(--transition-slow);
  pointer-events: none;
}

.feature-card:hover {
  transform: translateY(-8px);
  border-color: var(--color-card-border-hover);
  box-shadow:
    0 12px 48px rgba(44, 95, 69, 0.1),
    0 4px 12px rgba(0, 0, 0, 0.06);
  background: var(--color-card-bg-hover);
}

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

.feature-icon {
  width: 52px;
  height: 52px;
  margin-bottom: 1.5rem;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--color-primary-dim);
  border-radius: 50%;
  padding: 10px;
  border: 1px solid var(--color-border-medium);
}

.feature-icon svg {
  width: 100%;
  height: 100%;
}

.feature-title {
  font-family: var(--font-heading);
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 0.75rem;
  letter-spacing: 0.02em;
}

.feature-desc {
  font-size: 0.925rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* ============================================================
   STATS SECTION
   ============================================================ */

.stats {
  padding: clamp(4rem, 10vw, 8rem) 0;
  position: relative;
  background: var(--color-bg-alt);
  overflow: hidden;
}

/* Background Shapes */

.stats-bg-shapes {
  position: absolute;
  inset: 0;
  pointer-events: none;
  overflow: hidden;
}

.shape {
  position: absolute;
  border: 1px solid rgba(44, 95, 69, 0.08);
  border-radius: 50%;
}

.shape-1 {
  width: 400px;
  height: 400px;
  top: -100px;
  left: -100px;
}

.shape-2 {
  width: 300px;
  height: 300px;
  bottom: -80px;
  right: -60px;
}

.shape-3 {
  width: 200px;
  height: 200px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0.4;
}

.stats-list {
  display: flex;
  justify-content: center;
  gap: clamp(3rem, 8vw, 6rem);
  flex-wrap: wrap;
}

.stat-item {
  text-align: center;
  position: relative;
  padding: 2rem 1.5rem;
}

.stat-glow {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 160px;
  height: 160px;
  background: radial-gradient(circle, rgba(44, 95, 69, 0.12), transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  z-index: 0;
}

.stat-number {
  font-family: var(--font-mono);
  font-size: clamp(3rem, 6vw, 5rem);
  font-weight: 700;
  color: var(--color-primary);
  position: relative;
  z-index: 1;
  display: inline-block;
  text-shadow: 0 0 40px rgba(44, 95, 69, 0.15);
}

.stat-suffix {
  font-family: var(--font-mono);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 700;
  color: var(--color-accent);
  position: relative;
  z-index: 1;
  margin-left: 0.2rem;
}

.stat-label {
  display: block;
  font-family: var(--font-heading);
  font-size: 1.2rem;
  color: var(--color-text-secondary);
  margin-top: 0.5rem;
  position: relative;
  z-index: 1;
  letter-spacing: 0.06em;
}

/* ============================================================
   DOWNLOAD CTA SECTION
   ============================================================ */

.download {
  position: relative;
  padding: clamp(4rem, 10vw, 6rem) 0 clamp(5rem, 12vw, 8rem);
  background: linear-gradient(180deg, transparent, rgba(140, 90, 62, 0.03) 30%, var(--color-bg-alt));
}

.download-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: clamp(1.2rem, 2vw, 1.8rem);
  max-width: 900px;
  margin: 0 auto;
}

.download-card {
  background: var(--color-card-bg);
  border: 1px solid var(--color-card-border);
  border-radius: var(--radius-lg);
  padding: clamp(1.8rem, 3vw, 2.5rem);
  text-align: center;
  backdrop-filter: blur(24px) saturate(180%);
  -webkit-backdrop-filter: blur(24px) saturate(180%);
  transition:
    transform var(--transition-slow),
    box-shadow var(--transition-slow),
    border-color var(--transition-slow),
    background var(--transition-slow);
  cursor: default;
  position: relative;
  overflow: hidden;
}

.download-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background: radial-gradient(ellipse at 50% 0%, rgba(44, 95, 69, 0.1), transparent 75%);
  opacity: 0;
  transition: opacity var(--transition-slow);
  pointer-events: none;
}

.download-card:hover {
  transform: translateY(-8px);
  border-color: var(--color-card-border-hover);
  box-shadow:
    0 12px 48px rgba(44, 95, 69, 0.1),
    0 4px 12px rgba(0, 0, 0, 0.06);
  background: var(--color-card-bg-hover);
}

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

.download-icon-wrap {
  width: 56px;
  height: 56px;
  margin: 0 auto 1.2rem;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--color-primary-dim);
  border: 1px solid var(--color-border-medium);
}

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

.download-title {
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 0.4rem;
  letter-spacing: 0.04em;
}

.download-platform {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: 1rem;
}

.download-badge {
  display: inline-block;
  padding: 0.3rem 1rem;
  border-radius: 100px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

.badge-ready {
  background: rgba(140, 90, 62, 0.08);
  color: var(--color-accent);
  border: 1px solid rgba(140, 90, 62, 0.2);
}

/* ============================================================
   FOOTER
   ============================================================ */

.footer {
  padding: clamp(2.5rem, 5vw, 4rem) var(--container-padding);
  border-top: 1px solid rgba(44, 95, 69, 0.08);
  text-align: center;
}

.footer-container {
  max-width: var(--container-max);
  margin: 0 auto;
}

.footer-brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.3rem;
  margin-bottom: 1.5rem;
}

.footer-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 0.6rem;
  opacity: 0.7;
}

.footer-logo {
  font-family: var(--font-heading);
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-text);
  letter-spacing: 0.06em;
}

.footer-logo-en {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--color-primary);
  letter-spacing: 0.1em;
}

.footer-copy {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.4rem;
}

.footer-tagline {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--color-text-muted);
  letter-spacing: 0.05em;
  opacity: 0.6;
}

.footer-beian {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--color-text-muted);
  margin-top: 0.5rem;
  transition: color var(--transition-base);
}

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

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

.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1),
              transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered reveal for cards */
.feature-card.reveal[data-delay="0"],
.download-card.reveal[data-delay="0"] {
  transition-delay: 0s;
}

.feature-card.reveal[data-delay="1"],
.download-card.reveal[data-delay="1"] {
  transition-delay: 0.12s;
}

.feature-card.reveal[data-delay="2"],
.download-card.reveal[data-delay="2"] {
  transition-delay: 0.24s;
}

/* ============================================================
   RESPONSIVE: Tablet (768px - 1024px)
   ============================================================ */

@media (max-width: 1024px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .download-grid {
    grid-template-columns: repeat(3, 1fr);
    max-width: 700px;
  }
}

/* ============================================================
   RESPONSIVE: Mobile (< 768px)
   ============================================================ */

@media (max-width: 768px) {
  .features-grid {
    grid-template-columns: 1fr;
    max-width: 420px;
    margin: 0 auto;
  }

  .download-grid {
    grid-template-columns: 1fr;
    max-width: 320px;
  }

  .hero-title {
    font-size: clamp(2.5rem, 10vw, 4rem);
  }

  .hero-badge {
    font-size: 0.7rem;
    padding: 0.3rem 1rem;
  }

  .hero-desc {
    font-size: 0.9rem;
  }

  .stats-list {
    gap: 1.5rem;
  }

  .stat-glow {
    width: 90px;
    height: 90px;
  }

  .section-title {
    font-size: 1.8rem;
  }

  .hero-scroll-indicator {
    display: none;
  }

  .btn {
    padding: 0.75rem 1.8rem;
    font-size: 0.8rem;
  }
}

/* ============================================================
   RESPONSIVE: Small Mobile (< 480px)
   ============================================================ */

@media (max-width: 480px) {
  .hero-cta {
    flex-direction: column;
    align-items: center;
    gap: 0.8rem;
  }

  .btn {
    width: 100%;
    justify-content: center;
    max-width: 280px;
  }

  .stats-list {
    flex-direction: column;
    align-items: center;
    gap: 1rem;
  }

  .stat-item {
    padding: 1.2rem;
  }
}

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

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 4px;
  border-radius: 4px;
}

/* Reduced motion preference */
@media (prefers-reduced-motion: reduce) {
  .stagger-item {
    animation: none;
    opacity: 1;
    transform: none;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }

  .hero-scroll-indicator {
    animation: none;
  }
}