/* ===== Base ===== */
:root {
  --bg: #fbfbf9;
  --surface: #ffffff;
  --text: #1f2328;
  --text-soft: #57606a;
  --text-muted: #8b949e;
  --border: #ebe9e4;
  --accent: #2f5d7c;
  --accent-soft: #eef4f8;
  --shadow: 0 1px 2px rgba(20, 30, 40, .04), 0 6px 24px rgba(20, 30, 40, .05);
  --shadow-hover: 0 2px 6px rgba(20, 30, 40, .06), 0 14px 40px rgba(20, 30, 40, .09);
  --radius: 14px;
  --max: 1080px;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --serif: "Source Han Serif SC", "Noto Serif CJK SC", "Songti SC", Georgia, serif;
  --mono: "SFMono-Regular", "JetBrains Mono", Consolas, "Liberation Mono", Menlo, monospace;
}

:root[data-theme="dark"] {
  --bg: #0d1117;
  --surface: #161b22;
  --text: #e6edf3;
  --text-soft: #b1bac4;
  --text-muted: #7d8590;
  --border: #262d35;
  --accent: #6cb6e3;
  --accent-soft: #1a2530;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3), 0 6px 24px rgba(0, 0, 0, .35);
  --shadow-hover: 0 2px 6px rgba(0, 0, 0, .4), 0 14px 40px rgba(0, 0, 0, .5);
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  transition: background-color .3s ease, color .3s ease;
}

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

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

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
  transition: background-color .3s ease, border-color .3s ease;
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}
.header-right {
  display: flex;
  align-items: center;
  gap: 22px;
}
.brand {
  color: var(--text);
  font-weight: 650;
  font-size: 17px;
  letter-spacing: .02em;
}
.nav { display: flex; gap: 26px; }
.nav a {
  color: var(--text-soft);
  font-size: 14.5px;
  transition: color .2s;
}
.nav a:hover { color: var(--accent); }

/* ===== Theme toggle ===== */
.theme-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border: 1px solid var(--border);
  border-radius: 50%;
  background: transparent;
  color: var(--text-soft);
  cursor: pointer;
  padding: 0;
  transition: color .2s, border-color .2s;
}
.theme-toggle:hover {
  color: var(--accent);
  border-color: color-mix(in srgb, var(--accent) 40%, var(--border));
}
.theme-toggle .icon-sun { display: none; }
.theme-toggle .icon-moon { display: block; }
[data-theme="dark"] .theme-toggle .icon-sun { display: block; }
[data-theme="dark"] .theme-toggle .icon-moon { display: none; }

/* ===== Hero ===== */
.hero {
  padding: 88px 0 56px;
  text-align: center;
}
.hero-title {
  margin: 0 0 14px;
  font-size: clamp(40px, 7vw, 64px);
  font-weight: 680;
  letter-spacing: -.02em;
  line-height: 1.1;
  background: linear-gradient(135deg, var(--text) 30%, var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-sub {
  margin: 0;
  color: var(--text-soft);
  font-size: 17px;
}

/* ===== Card grid ===== */
.posts {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 22px;
  padding-bottom: 96px;
}
.card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 26px 24px;
  box-shadow: var(--shadow);
  color: var(--text);
  transition: transform .22s cubic-bezier(.2,.7,.3,1), box-shadow .22s, border-color .22s, background-color .3s ease, color .3s ease;
}
.card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
  border-color: color-mix(in srgb, var(--accent) 35%, var(--border));
}
.card-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 16px;
}
.card-date {
  font-size: 12.5px;
  color: var(--text-muted);
  font-variant-numeric: tabular-nums;
  letter-spacing: .03em;
}
.card-tag {
  font-size: 11.5px;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 2px 9px;
  border-radius: 999px;
  font-weight: 500;
}
.card-title {
  margin: 0 0 10px;
  font-size: 19.5px;
  font-weight: 620;
  line-height: 1.4;
  letter-spacing: -.01em;
}
.card-desc {
  margin: 0 0 20px;
  color: var(--text-soft);
  font-size: 14.5px;
  line-height: 1.65;
  flex: 1;
}
.card-more {
  font-size: 14px;
  color: var(--accent);
  font-weight: 500;
  align-self: flex-start;
  transition: transform .2s;
}
.card:hover .card-more { transform: translateX(3px); }

/* ===== Post ===== */
.post { padding: 64px 0 96px; max-width: 760px; margin: 0 auto; }
.post-header { margin-bottom: 40px; }
.post-tag {
  display: inline-block;
  font-size: 12px;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 11px;
  border-radius: 999px;
  margin-bottom: 18px;
  font-weight: 500;
}
.post-title {
  margin: 0 0 14px;
  font-size: clamp(28px, 4vw, 38px);
  font-weight: 680;
  line-height: 1.25;
  letter-spacing: -.015em;
}
.post-meta {
  color: var(--text-muted);
  font-size: 14px;
  font-variant-numeric: tabular-nums;
}
.post-content { font-size: 16.5px; line-height: 1.85; }
.post-content h2 {
  margin: 48px 0 18px;
  font-size: 23px;
  font-weight: 640;
  letter-spacing: -.01em;
  padding-bottom: .3em;
  border-bottom: 1px solid var(--border);
}
.post-content h3 { margin: 36px 0 14px; font-size: 19px; font-weight: 620; }
.post-content p { margin: 18px 0; }
.post-content ul, .post-content ol { padding-left: 1.5em; }
.post-content li { margin: .5em 0; }
.post-content blockquote {
  margin: 22px 0;
  padding: 2px 20px;
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 8px 8px 0;
  color: var(--text-soft);
}
.post-content blockquote p { margin: 12px 0; }
.post-content a { text-decoration: underline; text-underline-offset: 3px; text-decoration-color: color-mix(in srgb, var(--accent) 40%, transparent); }
.post-content a:hover { text-decoration-color: var(--accent); }
.post-content img { max-width: 100%; border-radius: 10px; }

.post-content table {
  display: block;
  overflow-x: auto;
  border-collapse: collapse;
  margin: 22px 0;
  font-size: 14.5px;
}
.post-content th, .post-content td {
  border: 1px solid var(--border);
  padding: 9px 14px;
  text-align: left;
}
.post-content th { background: var(--accent-soft); font-weight: 620; }
.post-content tr:nth-child(even) td { background: color-mix(in srgb, var(--bg) 50%, transparent); }

/* code */
.post-content code, .post-content pre {
  font-family: var(--mono);
  font-size: 14px;
}
.post-content :not(pre) > code {
  background: var(--accent-soft);
  color: var(--accent);
  padding: 2px 6px;
  border-radius: 5px;
  font-size: .88em;
}
.post-content pre {
  background: color-mix(in srgb, var(--surface) 60%, #000 4%);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 18px 20px;
  overflow-x: auto;
  line-height: 1.6;
}
.post-content pre code { background: none; padding: 0; color: inherit; }
.post-content hr { border: none; border-top: 1px solid var(--border); margin: 40px 0; }

.post-footer { margin-top: 64px; padding-top: 24px; border-top: 1px solid var(--border); }
.back-link { color: var(--text-soft); font-size: 14.5px; }
.back-link:hover { color: var(--accent); }

/* ===== Footer ===== */
.site-footer {
  border-top: 1px solid var(--border);
  padding: 28px 0;
  color: var(--text-muted);
  font-size: 13.5px;
  transition: border-color .3s ease, color .3s ease;
}
.footer-dot { margin: 0 8px; opacity: .6; }

/* ===== Responsive ===== */
@media (max-width: 640px) {
  .hero { padding: 56px 0 40px; }
  .post { padding: 40px 0 72px; }
  .posts { grid-template-columns: 1fr; gap: 16px; padding-bottom: 64px; }
  .nav { gap: 18px; }
}