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

:root {
  --bg: #fafbfc;
  --bg-alt: #f0f2f5;
  --text: #1a1a2e;
  --text-muted: #555;
  --accent: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-light: #dbeafe;
  --border: #e2e8f0;
  --card-bg: #fff;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --radius: 12px;
  --radius-sm: 8px;
  --max-w: 1100px;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "SF Mono", "Fira Code", "Consolas", monospace;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent);
  text-decoration: none;
  transition: color 0.2s;
}
a:hover {
  color: var(--accent-hover);
}

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

/* ===== Navigation ===== */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 251, 252, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
  height: 60px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text);
}
.nav-logo:hover {
  color: var(--accent);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 20px;
}

.nav-links a {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s;
}
.nav-links a:hover {
  color: var(--text);
}

.lang-btn {
  padding: 4px 12px;
  font-size: 0.8rem;
  font-weight: 600;
  border: 1.5px solid var(--accent);
  border-radius: 6px;
  background: transparent;
  color: var(--accent);
  cursor: pointer;
  transition: all 0.2s;
  min-width: 42px;
}
.lang-btn:hover {
  background: var(--accent);
  color: #fff;
}

/* ===== Hero ===== */
.hero {
  padding: 100px 0 80px;
  text-align: center;
  background: linear-gradient(180deg, var(--accent-light) 0%, var(--bg) 100%);
}

.hero h1 {
  font-size: 2.8rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
}

.hero-sub {
  font-size: 1.15rem;
  color: var(--text-muted);
  max-width: 700px;
  margin: 0 auto 28px;
  line-height: 1.8;
}

.hero-badges {
  display: flex;
  justify-content: center;
  gap: 10px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}

.badge {
  padding: 5px 14px;
  font-size: 0.82rem;
  font-weight: 600;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: 20px;
  color: var(--text-muted);
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
}

.btn {
  display: inline-block;
  padding: 12px 28px;
  font-size: 0.95rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  transition: all 0.2s;
  cursor: pointer;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border: 2px solid var(--accent);
}
.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: #fff;
}

.btn-outline {
  background: transparent;
  color: var(--accent);
  border: 2px solid var(--accent);
}
.btn-outline:hover {
  background: var(--accent);
  color: #fff;
}

/* ===== Sections ===== */
.section {
  padding: 80px 0;
}

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

.section h2 {
  font-size: 2rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 12px;
}

.section-desc {
  text-align: center;
  color: var(--text-muted);
  max-width: 680px;
  margin: 0 auto 48px;
  font-size: 1.05rem;
}

/* ===== Feature Grid ===== */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 20px;
}

.feature-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: box-shadow 0.2s, transform 0.2s;
}
.feature-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.feature-icon {
  font-size: 1.8rem;
  margin-bottom: 12px;
}

.feature-card h3 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.feature-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
}

.feature-card > a {
  display: inline-block;
  margin-top: 12px;
  font-size: 0.85rem;
  font-weight: 600;
}

/* ===== Install ===== */
.install-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
}

.install-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
}

.install-card h3 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--accent);
}

.install-card code {
  display: block;
  background: #1e293b;
  color: #e2e8f0;
  padding: 14px 16px;
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.6;
  overflow-x: auto;
  white-space: pre-wrap;
  word-break: break-all;
}

.install-note {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ===== Usage ===== */
.usage-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
}

.usage-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
}

.usage-tag {
  display: inline-block;
  padding: 3px 10px;
  font-size: 0.75rem;
  font-weight: 600;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 4px;
  margin-bottom: 12px;
}

.usage-zh {
  font-size: 0.92rem;
  margin-bottom: 10px;
  line-height: 1.7;
}

.usage-en {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
  font-style: italic;
}

/* ===== Tree ===== */
.tree {
  background: #1e293b;
  border-radius: var(--radius);
  padding: 28px 32px;
  overflow-x: auto;
}

.tree pre {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.7;
  color: #e2e8f0;
  margin: 0;
  white-space: pre;
}

.tree pre span {
  color: #94a3b8;
}

/* ===== Flow ===== */
.flow {
  display: flex;
  align-items: flex-start;
  justify-content: center;
  gap: 8px;
  flex-wrap: wrap;
}

.flow-step {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 18px;
  text-align: center;
  min-width: 150px;
  max-width: 180px;
  flex: 1;
}

.flow-num {
  width: 32px;
  height: 32px;
  background: var(--accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  margin: 0 auto 10px;
}

.flow-step h4 {
  font-size: 0.88rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.flow-step p {
  font-size: 0.78rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.flow-arrow {
  font-size: 1.4rem;
  color: var(--accent);
  font-weight: 300;
  padding-top: 36px;
}

/* ===== Principles ===== */
.principles-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 16px;
}

.principle {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
}

.principle-icon {
  font-size: 1.4rem;
  flex-shrink: 0;
  margin-top: 2px;
}

.principle p {
  font-size: 0.9rem;
  line-height: 1.6;
}

/* ===== Footer ===== */
.footer {
  padding: 40px 0;
  text-align: center;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-version {
  margin-top: 8px;
  font-size: 0.8rem;
  opacity: 0.7;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-links a:not(:last-child) {
    display: none;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero-sub {
    font-size: 1rem;
  }

  .section {
    padding: 56px 0;
  }

  .section h2 {
    font-size: 1.6rem;
  }

  .flow {
    flex-direction: column;
    align-items: center;
  }

  .flow-arrow {
    transform: rotate(90deg);
    padding: 0;
  }

  .flow-step {
    max-width: 100%;
    width: 100%;
  }

  .install-grid,
  .usage-grid,
  .principles-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .hero {
    padding: 72px 0 56px;
  }

  .hero h1 {
    font-size: 1.7rem;
  }

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