:root {
  --font-display: "SF Pro Display", "PingFang SC", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --font-body: "SF Pro Text", "PingFang SC", "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui, sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Cascadia Code", Menlo, Consolas, monospace;
  --max-width: 1120px;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --transition-fast: 0.2s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04), 0 1px 2px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 4px 16px rgba(0, 0, 0, 0.06), 0 2px 4px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 12px 40px rgba(0, 0, 0, 0.08), 0 4px 12px rgba(0, 0, 0, 0.04);
}

[data-theme="light"] {
  --bg-primary: #fafafa;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f5f5f7;
  --bg-elevated: #ffffff;
  --text-primary: #1d1d1f;
  --text-secondary: #6e6e73;
  --text-tertiary: #86868b;
  --border-primary: rgba(0, 0, 0, 0.08);
  --border-secondary: rgba(0, 0, 0, 0.04);
  --accent: #0071e3;
  --accent-hover: #0077ed;
  --accent-subtle: rgba(0, 113, 227, 0.08);
  --green: #34c759;
  --green-subtle: rgba(52, 199, 89, 0.1);
  --glow-1: rgba(0, 113, 227, 0.12);
  --glow-2: rgba(52, 199, 89, 0.08);
  --code-bg: #f5f5f7;
  --overlay: rgba(0, 0, 0, 0.5);
  --card-shadow: 0 2px 12px rgba(0, 0, 0, 0.06), 0 0 1px rgba(0, 0, 0, 0.08);
  --card-shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.1), 0 0 1px rgba(0, 0, 0, 0.08);
}

[data-theme="dark"] {
  --bg-primary: #000000;
  --bg-secondary: #1c1c1e;
  --bg-tertiary: #2c2c2e;
  --bg-elevated: #1c1c1e;
  --text-primary: #f5f5f7;
  --text-secondary: #a1a1a6;
  --text-tertiary: #86868b;
  --border-primary: rgba(255, 255, 255, 0.08);
  --border-secondary: rgba(255, 255, 255, 0.04);
  --accent: #2997ff;
  --accent-hover: #4db2ff;
  --accent-subtle: rgba(41, 151, 255, 0.12);
  --green: #30d158;
  --green-subtle: rgba(48, 209, 88, 0.12);
  --glow-1: rgba(41, 151, 255, 0.15);
  --glow-2: rgba(48, 209, 88, 0.1);
  --code-bg: #2c2c2e;
  --overlay: rgba(0, 0, 0, 0.7);
  --card-shadow: 0 2px 12px rgba(0, 0, 0, 0.3), 0 0 1px rgba(255, 255, 255, 0.05);
  --card-shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.4), 0 0 1px rgba(255, 255, 255, 0.08);
}

*, *::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(--bg-primary);
  color: var(--text-primary);
  line-height: 1.5;
  transition: background-color var(--transition-slow), color var(--transition-slow);
  overflow-x: hidden;
}

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

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

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

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

/* === NAV === */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(250, 250, 250, 0.72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid var(--border-secondary);
  transition: background var(--transition-slow), border-color var(--transition-slow);
}

[data-theme="dark"] .nav {
  background: rgba(0, 0, 0, 0.72);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 52px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 1rem;
  color: var(--text-primary);
  text-decoration: none;
}

.nav-brand svg {
  width: 28px;
  height: 28px;
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

.nav-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: 50%;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.nav-btn:hover {
  background: var(--accent-subtle);
  color: var(--accent);
}

.nav-btn svg {
  width: 18px;
  height: 18px;
}

.nav-lang {
  font-family: var(--font-body);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 20px;
  background: var(--accent-subtle);
  color: var(--accent);
  border: none;
  cursor: pointer;
  transition: background var(--transition-fast), color var(--transition-fast);
}

.nav-lang:hover {
  background: var(--accent);
  color: #fff;
}

/* === HERO === */
.hero {
  position: relative;
  padding: 160px 0 100px;
  text-align: center;
  overflow: hidden;
}

.hero-glow {
  position: absolute;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--glow-1) 0%, var(--glow-2) 40%, transparent 70%);
  filter: blur(80px);
  pointer-events: none;
  opacity: 0.6;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border-radius: 20px;
  background: var(--accent-subtle);
  color: var(--accent);
  font-size: 0.8rem;
  font-weight: 500;
  margin-bottom: 24px;
}

.hero-badge svg {
  width: 14px;
  height: 14px;
}

.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 6vw, 4.5rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.08;
  margin-bottom: 20px;
}

.hero h1 .gradient-text {
  background: linear-gradient(135deg, var(--accent) 0%, var(--green) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: clamp(1.05rem, 2vw, 1.25rem);
  color: var(--text-secondary);
  max-width: 580px;
  margin: 0 auto 40px;
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-body);
  font-size: 0.95rem;
  font-weight: 500;
  padding: 12px 24px;
  border-radius: 980px;
  border: none;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  line-height: 1.2;
}

.btn svg {
  width: 18px;
  height: 18px;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--accent-hover);
  color: #fff;
  transform: scale(1.02);
}

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

.btn-secondary:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: scale(1.02);
}

/* === SECTIONS === */
.section {
  padding: 100px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 64px;
}

.section-label {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 12px;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 560px;
  margin: 0 auto;
  line-height: 1.6;
}

/* === FEATURES === */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
}

.feature-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: 32px;
  transition: all var(--transition-base);
  cursor: default;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--card-shadow-hover);
  border-color: var(--accent);
}

.feature-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  margin-bottom: 20px;
  font-size: 1.4rem;
}

.feature-icon.system {
  background: var(--accent-subtle);
  color: var(--accent);
}

.feature-icon.encoding {
  background: var(--green-subtle);
  color: var(--green);
}

.feature-icon.data {
  background: rgba(255, 149, 0, 0.1);
  color: #ff9f0a;
}

.feature-icon.security {
  background: rgba(175, 82, 222, 0.1);
  color: #af52de;
}

.feature-icon.calculator {
  background: rgba(90, 200, 250, 0.1);
  color: #5ac8fa;
}

.feature-card h3 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
  line-height: 1.5;
}

.feature-tools {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.tool-tag {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 6px;
  background: var(--bg-tertiary);
  color: var(--text-tertiary);
  font-size: 0.75rem;
  font-weight: 500;
  transition: all var(--transition-fast);
}

.feature-card:hover .tool-tag {
  background: var(--accent-subtle);
  color: var(--accent);
}

/* === SCREENSHOTS === */
.screenshots-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.screenshot-item {
  position: relative;
  aspect-ratio: 16 / 10;
  border-radius: var(--radius-lg);
  overflow: hidden;
  cursor: pointer;
  transition: all var(--transition-base);
  border: 1px solid var(--border-primary);
  background: var(--bg-elevated);
}

.screenshot-item:hover {
  transform: scale(1.02);
  box-shadow: var(--card-shadow-hover);
}

.screenshot-item img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--transition-base);
}

.screenshot-light,
.screenshot-dark {
  position: absolute;
  inset: 0;
}

[data-theme="light"] .screenshot-dark,
[data-theme="dark"] .screenshot-light {
  display: none;
}

.screenshot-item:hover img {
  transform: scale(1.04);
}

.screenshot-label {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  padding: 16px 20px;
  background: linear-gradient(transparent, rgba(0, 0, 0, 0.6));
  color: #fff;
  font-size: 0.85rem;
  font-weight: 500;
  opacity: 0;
  transform: translateY(8px);
  transition: all var(--transition-base);
}

.screenshot-item:hover .screenshot-label {
  opacity: 1;
  transform: translateY(0);
}

/* === HIGHLIGHTS === */
.highlights-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 20px;
}

.highlight-card {
  background: var(--bg-elevated);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-lg);
  padding: 36px;
  display: flex;
  gap: 20px;
  align-items: flex-start;
  transition: all var(--transition-base);
}

.highlight-card:hover {
  border-color: var(--accent);
  box-shadow: var(--card-shadow-hover);
}

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

.highlight-card h3 {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 600;
  margin-bottom: 6px;
}

.highlight-card p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* === QUICK START === */
.quickstart {
  text-align: center;
}

.code-block-wrapper {
  position: relative;
  display: inline-block;
  background: var(--code-bg);
  border: 1px solid var(--border-primary);
  border-radius: var(--radius-md);
  padding: 20px 60px 20px 28px;
  margin-top: 24px;
  text-align: left;
  max-width: 100%;
}

.code-block-wrapper code {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--text-primary);
  white-space: nowrap;
}

.code-copy {
  position: absolute;
  top: 50%;
  right: 12px;
  transform: translateY(-50%);
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-tertiary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.code-copy:hover {
  background: var(--accent-subtle);
  color: var(--accent);
}

.code-copy.copied {
  color: var(--green);
}

.code-copy svg {
  width: 16px;
  height: 16px;
}

/* === FOOTER === */
.footer {
  border-top: 1px solid var(--border-primary);
  padding: 40px 0;
  transition: border-color var(--transition-slow);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.footer-copy {
  font-size: 0.85rem;
  color: var(--text-tertiary);
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.footer-links a {
  font-size: 0.85rem;
  color: var(--text-tertiary);
  transition: color var(--transition-fast);
}

.footer-links a:hover {
  color: var(--accent);
}

/* === MODAL === */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: var(--overlay);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px;
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-base);
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  max-width: 900px;
  max-height: 85vh;
  border-radius: var(--radius-lg);
  overflow: hidden;
  transform: scale(0.92);
  transition: transform var(--transition-base);
  background: var(--bg-elevated);
  box-shadow: var(--shadow-lg);
}

.modal-overlay.active .modal-content {
  transform: scale(1);
}

.modal-content img {
  width: 100%;
  height: auto;
}

/* === SCROLL ANIMATIONS === */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

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

.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

@media (prefers-reduced-motion: reduce) {
  .reveal {
    opacity: 1;
    transform: none;
    transition: none;
  }
  html {
    scroll-behavior: auto;
  }
}

/* === RESPONSIVE === */
@media (max-width: 1024px) {
  .screenshots-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .screenshots-grid .screenshot-item:last-child {
    grid-column: span 2;
    max-width: 50%;
    margin: 0 auto;
  }
}

@media (max-width: 768px) {
  .hero {
    padding: 120px 0 72px;
  }
  .section {
    padding: 72px 0;
  }
  .section-header {
    margin-bottom: 48px;
  }
  .screenshots-grid {
    grid-template-columns: 1fr;
  }
  .screenshots-grid .screenshot-item:last-child {
    grid-column: auto;
    max-width: 100%;
  }
  .highlights-grid {
    grid-template-columns: 1fr;
  }
  .highlight-card {
    padding: 28px;
  }
  .hero-actions {
    flex-direction: column;
    width: 100%;
  }
  .hero-actions .btn {
    width: 100%;
    justify-content: center;
  }
  .footer-inner {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }
  .code-block-wrapper {
    width: 100%;
    box-sizing: border-box;
  }
  .code-block-wrapper code {
    font-size: 0.82rem;
    white-space: normal;
    word-break: break-all;
  }
  .modal-overlay {
    padding: 20px;
  }
}