:root {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-card: #ffffff;
  --bg-code: #f6f8fa;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --accent: #6366f1;
  --accent-2: #8b5cf6;
  --accent-3: #ec4899;
  --border: #e2e8f0;
  --success: #10b981;
  --warning: #f59e0b;
  --shadow: 0 10px 30px -5px rgba(99, 102, 241, 0.15), 0 4px 6px -4px rgba(99, 102, 241, 0.1);
}

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

html, body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei",
               "Helvetica Neue", Helvetica, Arial, sans-serif;
  font-size: 15px;
  line-height: 1.7;
  color: var(--text-primary);
  background: linear-gradient(135deg, #f5f7ff 0%, #fdf4ff 50%, #fef3f9 100%);
  min-height: 100vh;
}

/* ===== 顶部 Header ===== */
.site-header {
  background: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #ec4899 100%);
  color: #fff;
  padding: 18px 0;
  box-shadow: 0 4px 20px rgba(99,102,241,0.25);
  position: sticky;
  top: 0;
  z-index: 100;
}
.header-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  gap: 24px;
}
.brand {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.5px;
  white-space: nowrap;
}
.brand .emoji { font-size: 24px; margin-right: 6px; }
.tagline {
  color: rgba(255,255,255,0.85);
  font-size: 13px;
  margin-left: auto;
  font-weight: 400;
}
.back-blog {
  flex-shrink: 0;
  color: #fff;
  font-size: 13px;
  text-decoration: none;
  padding: 6px 14px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.45);
  background: rgba(255,255,255,0.12);
  transition: background .2s, transform .2s;
}
.back-blog:hover {
  background: rgba(255,255,255,0.25);
  transform: translateX(-2px);
}

/* ===== 主体 ===== */
.layout {
  max-width: 1280px;
  margin: 32px auto;
  padding: 0 24px;
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 32px;
}

/* ===== 侧边栏 ===== */
.sidebar {
  position: sticky;
  top: 92px;
  height: calc(100vh - 120px);
  overflow-y: auto;
  background: rgba(255,255,255,0.85);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 20px 16px;
  box-shadow: var(--shadow);
}
.sidebar h3 {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin: 14px 0 8px;
  padding-left: 8px;
}
.sidebar h3:first-child { margin-top: 0; }
.sidebar ul { list-style: none; }
.sidebar li { margin: 2px 0; }
.sidebar a {
  display: block;
  padding: 8px 12px;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 14px;
  border-radius: 8px;
  transition: all 0.2s;
  border-left: 3px solid transparent;
}
.sidebar a:hover {
  background: linear-gradient(90deg, rgba(99,102,241,0.08), transparent);
  color: var(--accent);
  border-left-color: var(--accent);
}
.sidebar a.active {
  background: linear-gradient(90deg, rgba(99,102,241,0.15), rgba(236,72,153,0.05));
  color: var(--accent);
  font-weight: 600;
  border-left-color: var(--accent);
}

/* ===== 主内容 ===== */
main {
  background: var(--bg-card);
  border-radius: 14px;
  padding: 40px 56px;
  box-shadow: var(--shadow);
  min-height: calc(100vh - 120px);
}

main h1, main h2, main h3, main h4 {
  color: var(--text-primary);
  font-weight: 700;
  margin-top: 1.6em;
  margin-bottom: 0.6em;
  line-height: 1.3;
}
main h1 {
  font-size: 32px;
  padding-bottom: 12px;
  border-bottom: 2px solid;
  border-image: linear-gradient(90deg, var(--accent), var(--accent-2)) 1;
  margin-top: 0.2em;
}
main h2 {
  font-size: 24px;
  padding-left: 14px;
  border-left: 4px solid var(--accent);
}
main h3 { font-size: 19px; color: var(--accent-2); }
main h4 { font-size: 16px; color: var(--text-secondary); }

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

main ul, main ol { padding-left: 24px; margin: 0.6em 0; }
main li { margin: 0.25em 0; }

main a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px dashed var(--accent);
  transition: color 0.2s;
}
main a:hover { color: var(--accent-2); }

/* 表格 */
main table {
  width: 100%;
  border-collapse: collapse;
  margin: 1em 0;
  font-size: 14px;
  border-radius: 8px;
  overflow: hidden;
  box-shadow: 0 1px 3px rgba(0,0,0,0.04);
}
main th {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
  text-align: left;
  padding: 12px 14px;
  font-weight: 600;
}
main td {
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
}
main tbody tr:nth-child(even) { background: #f9fafb; }
main tbody tr:hover { background: #f3f4ff; }

/* 代码 */
main code {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 6px;
  font-family: "JetBrains Mono", Consolas, "Courier New", monospace;
  font-size: 13px;
  color: #db2777;
}
main pre {
  background: #0f172a;
  color: #e2e8f0;
  padding: 18px 22px;
  border-radius: 10px;
  overflow-x: auto;
  margin: 1em 0;
  border-left: 4px solid var(--accent);
  box-shadow: 0 4px 14px rgba(15,23,42,0.15);
}
main pre code {
  background: none;
  border: none;
  padding: 0;
  color: inherit;
  font-size: 13.5px;
}

/* 引用 */
main blockquote {
  border-left: 4px solid var(--accent);
  background: linear-gradient(90deg, rgba(99,102,241,0.05), transparent);
  padding: 12px 18px;
  margin: 1em 0;
  color: var(--text-secondary);
  border-radius: 0 8px 8px 0;
}

/* 任务列表 */
main .task-list-item input[type="checkbox"] {
  margin-right: 6px;
  accent-color: var(--accent);
  transform: scale(1.1);
}
main .task-list-item { list-style: none; margin-left: -20px; }

/* 分割线 */
main hr {
  border: none;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
  margin: 2em 0;
}

/* 首页 hero */
.hero {
  background: linear-gradient(135deg, rgba(99,102,241,0.08), rgba(139,92,246,0.08), rgba(236,72,153,0.08));
  border-radius: 14px;
  padding: 36px 40px;
  margin-bottom: 32px;
  text-align: center;
}
.hero h1 {
  font-size: 38px;
  background: linear-gradient(135deg, #6366f1, #8b5cf6, #ec4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  border-bottom: none;
  margin-bottom: 10px;
}
.hero p { font-size: 16px; max-width: 720px; margin: 0 auto; color: var(--text-secondary); }

.cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
  margin: 24px 0;
}
.card {
  background: linear-gradient(135deg, #fff, #fafbff);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 22px 24px;
  transition: transform 0.2s, box-shadow 0.2s;
  text-decoration: none;
  color: var(--text-primary);
  position: relative;
  overflow: hidden;
}
.card:hover { transform: translateY(-3px); box-shadow: var(--shadow); }
.card::before {
  content: "";
  position: absolute;
  top: 0; left: 0;
  width: 4px; height: 100%;
  background: linear-gradient(180deg, var(--accent), var(--accent-2), var(--accent-3));
}
.card .num {
  display: inline-block;
  font-size: 12px;
  font-weight: 700;
  color: var(--accent);
  background: rgba(99,102,241,0.1);
  padding: 2px 10px;
  border-radius: 12px;
  margin-bottom: 8px;
}
.card h3 { font-size: 16px; margin: 6px 0 4px; color: var(--text-primary); border-left: none; padding-left: 0; }
.card p { font-size: 13px; color: var(--text-muted); margin-top: 4px; }

.footer {
  text-align: center;
  color: var(--text-muted);
  font-size: 13px;
  margin: 40px 0 20px;
  padding: 18px;
}

/* 滚动条 */
.sidebar::-webkit-scrollbar { width: 6px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--accent); border-radius: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }

@media (max-width: 860px) {
  .layout { grid-template-columns: 1fr; }
  .sidebar { position: relative; top: 0; height: auto; }
  main { padding: 24px 22px; }
  .hero h1 { font-size: 28px; }
}