:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #16181d;
  --text-2: #454b57;
  --muted: #858d99;
  --line: #e7e9ee;
  --line-2: #d3d8e0;
  --accent: #2563eb;
  --accent-soft: #edf2ff;
  --code-bg: #f5f7fa;
  --radius: 12px;
  --side-w: 252px;
  --col-w: 900px;
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", system-ui,
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 17px;
  line-height: 1.85;
  letter-spacing: .008em;
  overflow-wrap: break-word;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

.skip { position: absolute; left: -9999px; }
.skip:focus {
  left: 12px;
  top: 12px;
  background: var(--surface);
  padding: 8px 12px;
  border: 1px solid var(--line-2);
  border-radius: 6px;
  z-index: 9;
}

/* --------------------------------------------------------------- 骨架 */

.shell { display: flex; align-items: flex-start; min-height: 100vh; }

.col { flex: 1 1 auto; min-width: 0; display: flex; flex-direction: column; }

main {
  flex: 1 1 auto;
  width: 100%;
  max-width: var(--col-w);
  margin: 0 auto;
  padding: 56px 44px 0;
}

/* ------------------------------------------------------------- 左侧栏 */

.side {
  flex: 0 0 var(--side-w);
  width: var(--side-w);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  background: var(--surface);
  border-right: 1px solid var(--line);
}
.side-in {
  display: flex;
  flex-direction: column;
  gap: 26px;
  min-height: 100%;
  padding: 34px 18px 28px;
}

.brand { display: flex; align-items: center; gap: 11px; padding: 0 10px; }
.brand:hover { text-decoration: none; }
.brand-mark {
  flex: 0 0 auto;
  width: 34px;
  height: 34px;
  border-radius: 9px;
  background: var(--accent);
  color: #fff;
  display: grid;
  place-items: center;
  font-size: 16px;
  font-weight: 700;
}
.brand-txt { display: flex; flex-direction: column; min-width: 0; line-height: 1.4; }
.brand-name { font-size: 16.5px; font-weight: 650; color: var(--text); }
.brand-sub { font-size: 12px; color: var(--muted); }

.nav { display: flex; flex-direction: column; gap: 3px; }
.nav a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 9px 12px;
  border-radius: 9px;
  border: 1px solid transparent;
  font-size: 15.5px;
  color: var(--text-2);
}
.nav a:hover { background: #f1f3f7; color: var(--text); text-decoration: none; }
.nav a.on { background: var(--accent-soft); border-color: #dde5fb; color: var(--accent); font-weight: 600; }
.nav a b { font-size: 12.5px; font-weight: 500; color: var(--muted); font-variant-numeric: tabular-nums; }
.nav a.on b { color: var(--accent); }

.side-foot { margin: auto 0 0; padding: 0 12px; font-size: 12.5px; color: var(--muted); }
.side-foot b { color: var(--text-2); font-weight: 600; font-variant-numeric: tabular-nums; }

/* ---------------------------------------------------------------- 首页 */

.intro { padding-bottom: 28px; border-bottom: 1px solid var(--line); }
.intro h1 { font-size: clamp(28px, 4.6vw, 36px); margin: 0 0 12px; letter-spacing: -.018em; line-height: 1.25; }
.lede { margin: 0; font-size: 17px; line-height: 1.8; color: var(--text-2); }
.stats { margin: 14px 0 0; font-size: 14px; color: var(--muted); }
.stats b { color: var(--text-2); font-weight: 600; }
.stats a { color: var(--text-2); }
.stats a:hover { color: var(--accent); text-decoration: none; }

.sec { padding: 42px 0 4px; }
.sec-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line);
}
.sec-head h2 { font-size: 20px; margin: 0; letter-spacing: -.008em; }
.sec-head h2 a { color: var(--text); }
.sec-head h2 a:hover { color: var(--accent); text-decoration: none; }
.sec-head .count { font-size: 13px; color: var(--muted); }
.sec-intro { margin: 14px 0 0; font-size: 15px; line-height: 1.8; color: var(--text-2); }
.more { margin: 18px 0 0; font-size: 15px; }

.muted { color: var(--muted); font-size: 14px; margin: 0; }

/* ------------------------------------------------------------ 列表条目 */

.list { display: flex; flex-direction: column; }

.item { display: flex; gap: 26px; padding: 26px 0; border-bottom: 1px solid var(--line); }
.item:last-child { border-bottom: none; padding-bottom: 8px; }

.item-d {
  flex: 0 0 100px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
  padding-top: 5px;
}
.item-d time {
  font-size: 13px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.item-b { flex: 1 1 auto; min-width: 0; }
.item-t { display: block; font-size: 19px; font-weight: 630; line-height: 1.55; color: var(--text); letter-spacing: -.006em; }
.item-t:hover { color: var(--accent); text-decoration: none; }
.item-s { margin: 9px 0 0; font-size: 15.5px; color: var(--text-2); line-height: 1.8; }
.item-m { margin: 10px 0 0; font-size: 13px; color: var(--muted); }

.tag {
  display: inline-block;
  font-size: 12.5px;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 2px 10px;
  white-space: nowrap;
}

/* ---------------------------------------------------------- 栏目 / 文章 */

.page-t { font-size: clamp(26px, 4.2vw, 32px); margin: 14px 0 10px; letter-spacing: -.018em; line-height: 1.3; }
.crumb { margin: 0 0 20px; font-size: 13.5px; color: var(--muted); }
.crumb a { color: var(--muted); }
.crumb a:hover { color: var(--accent); text-decoration: none; }
.crumb span { margin: 0 7px; }

/* 文章正文区：把长文包进一块安静的白面，边缘留白撑开，降低四周干扰 */
.post {
  margin-top: 8px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 40px 52px 52px;
  box-shadow: 0 1px 2px rgba(16, 24, 40, .03), 0 12px 32px -18px rgba(16, 24, 40, .12);
}
.post-t { font-size: clamp(27px, 4.4vw, 34px); line-height: 1.32; margin: 8px 0 14px; letter-spacing: -.02em; }
.post-m {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
  margin: 0 0 34px;
  padding-bottom: 22px;
  border-bottom: 1px solid var(--line);
  font-size: 13.5px;
  color: var(--muted);
}

/* -------------------------------------------------------------- 正文 */

.prose { font-size: 17.5px; line-height: 1.9; color: #1f2229; letter-spacing: .01em; }
.prose > *:first-child { margin-top: 0; }
.prose h1, .prose h2, .prose h3, .prose h4 { line-height: 1.45; margin: 2.1em 0 .8em; letter-spacing: -.012em; color: #14161a; }
.prose h1 { font-size: 27px; }
.prose h2 { font-size: 24px; padding-bottom: .35em; border-bottom: 1px solid var(--line); }
.prose h3 { font-size: 20px; }
.prose h4 { font-size: 17.5px; color: var(--text-2); }
.prose p { margin: 0 0 1.3em; }
.prose ul, .prose ol { margin: 0 0 1.3em; padding-left: 1.5em; }
.prose li { margin: .5em 0; }
.prose li > ul, .prose li > ol { margin: .5em 0; }
.prose strong { font-weight: 650; color: #101216; }
.prose hr { border: none; border-top: 1px solid var(--line); margin: 2.4em 0; }

.prose blockquote {
  margin: 1.4em 0;
  padding: 6px 20px;
  border-left: 3px solid var(--line-2);
  border-radius: 0 8px 8px 0;
  background: var(--code-bg);
  color: var(--text-2);
}
.prose blockquote p { margin: .9em 0; }

.prose code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  font-size: .88em;
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 4px;
  padding: .12em .38em;
  overflow-wrap: break-word;
}
.prose pre {
  background: var(--code-bg);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 18px 20px;
  margin: 1.4em 0;
  overflow-x: auto;
  line-height: 1.7;
}
.prose pre code { background: none; border: none; padding: 0; font-size: 14px; }

.table-wrap {
  margin: 1.5em 0;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  overflow-x: auto;
}
.prose table { border-collapse: collapse; width: 100%; font-size: 15px; }
.prose th, .prose td {
  border-bottom: 1px solid var(--line);
  padding: 11px 15px;
  text-align: left;
  vertical-align: top;
  line-height: 1.7;
}
.prose thead th { background: #f7f8fa; font-weight: 630; white-space: nowrap; }
.prose tbody tr:last-child td { border-bottom: none; }

.fig { margin: 2em 0; text-align: center; }
.fig img {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
}
.fig figcaption { margin-top: 12px; font-size: 14px; color: var(--muted); line-height: 1.7; }
.fig.missing {
  border: 1px dashed var(--line-2);
  border-radius: 10px;
  padding: 20px;
  color: var(--muted);
  font-size: 14px;
}

/* ------------------------------------------------------------ 上下篇 */

.pager {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin: 52px 0 0;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}
.pg {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface);
  font-size: 15px;
  line-height: 1.6;
  color: var(--text);
}
.pg span { font-size: 12.5px; color: var(--muted); }
.pg:hover { border-color: var(--line-2); text-decoration: none; }
.pg.next { text-align: right; }
.pg.off { border: none; background: none; }
.back { margin: 26px 0 0; font-size: 15px; }

/* -------------------------------------------------------------- 页脚 */

.foot {
  width: 100%;
  max-width: var(--col-w);
  margin: 0 auto;
  padding: 36px 44px 56px;
  font-size: 13.5px;
  color: var(--muted);
}
.foot p { margin: 0 0 5px; }

/* ---------------------------------------------------------- 响应式 */

@media (max-width: 1000px) {
  .shell { display: block; }

  .side {
    position: sticky;
    top: 0;
    z-index: 6;
    width: auto;
    height: auto;
    flex: none;
    overflow: visible;
    border-right: none;
    border-bottom: 1px solid var(--line);
  }
  .side-in { gap: 12px; padding: 12px 18px 0; }
  .brand { padding: 0 2px; }
  .brand-sub { display: none; }

  .nav {
    flex-direction: row;
    gap: 7px;
    margin: 0 -18px;
    padding: 0 18px 12px;
    overflow-x: auto;
    scrollbar-width: none;
  }
  .nav::-webkit-scrollbar { display: none; }
  .nav a { flex: 0 0 auto; border: 1px solid var(--line); padding: 6px 14px; font-size: 14.5px; }
  .nav a b { margin-left: 6px; }

  .side-foot { display: none; }

  main { padding: 32px 22px 0; }
  .foot { padding: 28px 22px 44px; }

  .post { padding: 30px 28px 36px; border-radius: 14px; }
  .crumb { margin-bottom: 16px; }

  .sec { padding: 32px 0 2px; }
  .prose { font-size: 17px; }
}

@media (max-width: 640px) {
  body { font-size: 16.5px; line-height: 1.85; }

  main { padding: 22px 14px 0; }
  .foot { padding: 24px 14px 40px; }

  .post { padding: 24px 20px 30px; border-radius: 12px; }

  .item { flex-direction: column; gap: 12px; padding: 22px 0; }
  .item-b { order: 1; }
  .item-d { order: 2; flex-direction: row; align-items: center; gap: 10px; padding-top: 0; }
  .item-t { font-size: 18px; }
  .item-s { font-size: 15px; }
  .item-m { display: none; }

  .pager { grid-template-columns: 1fr; gap: 10px; }
  .pg.next { text-align: left; }

  .prose { font-size: 16.5px; line-height: 1.85; }
  .prose h1 { font-size: 23px; }
  .prose h2 { font-size: 21px; }
  .prose h3 { font-size: 18.5px; }
  .prose th, .prose td { padding: 9px 12px; }
}