:root {
  --bg: #ffffff;
  --bg-soft: #f6f7fb;
  --fg: #1f2430;
  --fg-muted: #6b7280;
  --accent: #4f46e5;
  --accent-soft: #eef2ff;
  --border: #e5e7eb;
  --code-bg: #1e1e2e;
  --shadow: 0 1px 3px rgba(17, 24, 39, 0.06), 0 8px 24px rgba(17, 24, 39, 0.06);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1117;
    --bg-soft: #161a22;
    --fg: #e5e7eb;
    --fg-muted: #9ca3af;
    --accent: #818cf8;
    --accent-soft: rgba(129, 140, 248, 0.12);
    --border: #262b36;
    --code-bg: #181c26;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.4), 0 8px 24px rgba(0, 0, 0, 0.4);
  }
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.7;
}

.container { max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* 顶部导航 */
.site-header {
  position: sticky; top: 0; z-index: 10;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: baseline; gap: 12px; height: 60px; }
.logo { font-size: 20px; font-weight: 800; color: var(--fg); text-decoration: none; letter-spacing: 0.5px; }
.logo span { color: var(--accent); }
.tagline { color: var(--fg-muted); font-size: 13px; }

/* 首页 hero */
.hero { padding: 64px 0 36px; }
.hero h1 {
  font-size: 46px; margin: 0 0 12px; letter-spacing: 1px;
  background: linear-gradient(120deg, var(--accent), #06b6d4);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero p { color: var(--fg-muted); margin: 0; font-size: 16px; }

.section-title {
  font-size: 13px; color: var(--fg-muted); text-transform: uppercase;
  letter-spacing: 2px; margin: 20px 0 16px;
}

/* 分类导航 */
.cat-nav {
  display: flex; flex-wrap: wrap; gap: 10px; margin: 4px 0 24px;
}
.chip {
  padding: 7px 16px; border-radius: 999px; border: 1px solid var(--border);
  background: var(--bg); color: var(--fg-muted); font-size: 14px; cursor: pointer;
  transition: all 0.15s ease; font-family: inherit;
}
.chip:hover { border-color: var(--accent); color: var(--accent); }
.chip.active { background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 600; }

/* 文章卡片 */
.cards {
  list-style: none; margin: 0 0 56px; padding: 0;
  display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 16px;
}
.card a {
  display: block; height: 100%; padding: 20px;
  border: 1px solid var(--border); border-radius: 14px;
  text-decoration: none; color: var(--fg); background: var(--bg-soft);
  transition: transform 0.15s ease, box-shadow 0.15s ease, border-color 0.15s ease;
}
.card a:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: var(--accent); }
.card-meta { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
.card-date { font-size: 12px; color: var(--fg-muted); font-variant-numeric: tabular-nums; }
.card-title { font-size: 17px; font-weight: 700; margin-bottom: 8px; line-height: 1.4; }
.card-excerpt { font-size: 14px; color: var(--fg-muted); }

/* 分类 badge */
.card-cat {
  display: inline-block; padding: 1px 10px; border-radius: 999px;
  font-size: 12px; font-weight: 600;
}
.cat-AI { background: rgba(79, 70, 229, 0.12); color: #4f46e5; }
.cat-ML { background: rgba(6, 182, 212, 0.12); color: #0891b2; }
.cat-Risk { background: rgba(245, 158, 11, 0.14); color: #b45309; }
.cat-Arch { background: rgba(236, 72, 153, 0.12); color: #be185d; }
.cat-未分类 { background: var(--accent-soft); color: var(--fg-muted); }
@media (prefers-color-scheme: dark) {
  .cat-AI { background: rgba(129, 140, 248, 0.15); color: #a5b4fc; }
  .cat-ML { background: rgba(34, 211, 238, 0.15); color: #67e8f9; }
  .cat-Risk { background: rgba(251, 191, 36, 0.15); color: #fcd34d; }
  .cat-Arch { background: rgba(244, 114, 182, 0.15); color: #f9a8d4; }
}

/* 文章页 */
.post { max-width: 780px; margin: 0 auto; padding: 40px 0 64px; }
.back { color: var(--accent); text-decoration: none; font-size: 14px; }
.back:hover { text-decoration: underline; }
.post-header { margin: 20px 0 28px; }
.post-date { color: var(--fg-muted); font-size: 13px; }
.post-title { font-size: 32px; margin: 8px 0 0; line-height: 1.3; }

.post-body { font-size: 16px; }
.post-body h1, .post-body h2, .post-body h3, .post-body h4 { line-height: 1.4; }
.post-body h2 { font-size: 24px; margin: 40px 0 16px; padding-bottom: 8px; border-bottom: 1px solid var(--border); }
.post-body h3 { font-size: 19px; margin: 28px 0 12px; }
.post-body p { margin: 14px 0; }
.post-body ul, .post-body ol { padding-left: 24px; }
.post-body li { margin: 6px 0; }
.post-body blockquote {
  margin: 16px 0; padding: 12px 16px;
  border-left: 4px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 8px 8px 0;
  color: var(--fg-muted);
}
.post-body blockquote p { margin: 0; }
.post-body code {
  font-family: "JetBrains Mono", "Cascadia Code", Consolas, monospace;
  font-size: 0.9em;
  background: var(--accent-soft); color: var(--accent);
  padding: 2px 6px; border-radius: 5px;
}
.post-body pre {
  background: var(--code-bg); color: #cdd6f4;
  padding: 18px 20px; border-radius: 12px; overflow-x: auto; margin: 18px 0;
}
.post-body pre code { background: none; color: inherit; padding: 0; font-size: 13.5px; line-height: 1.6; }
.post-body table { border-collapse: collapse; width: 100%; margin: 18px 0; font-size: 14.5px; }
.post-body th, .post-body td { border: 1px solid var(--border); padding: 8px 12px; text-align: left; }
.post-body th { background: var(--bg-soft); }
.post-body img { max-width: 100%; border-radius: 10px; }
.post-body a { color: var(--accent); }
.post-body hr { border: none; border-top: 1px solid var(--border); margin: 32px 0; }
.post-body strong { font-weight: 700; }

/* 页脚 */
.site-footer {
  border-top: 1px solid var(--border); padding: 28px 0;
  color: var(--fg-muted); font-size: 13px; text-align: center;
}