/* ============================================================
   技术笔记 · 主题变量
   ============================================================ */
:root {
  --bg: #ffffff;
  --bg-soft: #f6f8fa;
  --card: #ffffff;
  --card-hover: #ffffff;
  --border: #e5e7eb;
  --border-soft: #eef0f2;
  --text: #1f2328;
  --text-soft: #5b6570;
  --text-mute: #8b949e;
  --accent: #2f6feb;
  --accent-soft: rgba(47, 111, 235, 0.1);
  --code-bg: #f6f8fa;
  --shadow: 0 1px 2px rgba(16, 22, 26, 0.04), 0 4px 16px rgba(16, 22, 26, 0.04);
  --shadow-hover: 0 2px 6px rgba(16, 22, 26, 0.06), 0 12px 28px rgba(16, 22, 26, 0.08);
  --radius: 12px;
  --maxw: 1200px;
  color-scheme: light;
}

[data-theme="dark"] {
  --bg: #0d1117;
  --bg-soft: #12181f;
  --card: #151b23;
  --card-hover: #1a212b;
  --border: #262d38;
  --border-soft: #1e252e;
  --text: #e4e8ed;
  --text-soft: #a2adba;
  --text-mute: #7b8794;
  --accent: #58a6ff;
  --accent-soft: rgba(88, 166, 255, 0.14);
  --code-bg: #161b22;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 6px 20px rgba(0, 0, 0, 0.25);
  --shadow-hover: 0 4px 10px rgba(0, 0, 0, 0.35), 0 14px 34px rgba(0, 0, 0, 0.35);
  color-scheme: dark;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 88px; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  transition: background-color .2s ease, color .2s ease;
}

a { color: var(--accent); text-decoration: none; transition: color .15s ease; }
a:hover { color: var(--accent); text-decoration: underline; text-underline-offset: 3px; }
img { max-width: 100%; }
.muted { color: var(--text-mute); }

/* ============================================================
   页头：现代深色标题栏（editorial black，明暗主题下均保持深色）
   ============================================================ */
:root {
  --header-top: #191d24;
  --header-bottom: #0b0e13;
  --header-text: #f4f6f9;
  --header-soft: rgba(255, 255, 255, 0.72);
  --header-mute: rgba(255, 255, 255, 0.46);
  --header-line: rgba(255, 255, 255, 0.09);
  --header-focus: #5aa2ff;
}
[data-theme="dark"] {
  --header-top: #10141a;
  --header-bottom: #06080b;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: linear-gradient(180deg, var(--header-top), var(--header-bottom) 72%);
  color: var(--header-text);
  border-bottom: 1px solid var(--header-line);
  box-shadow: 0 10px 26px rgba(0, 0, 0, 0.16);
}

.banner-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 16px 28px;
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 18px;
}

.banner-side { display: flex; align-items: center; gap: 4px; }
.banner-left  { justify-content: flex-start; flex-wrap: wrap; }
.banner-right { justify-content: flex-end; gap: 10px; flex-wrap: wrap; }

.banner-center { text-align: center; min-width: 0; }
.banner-brand { color: var(--header-text); }
.banner-brand:hover { color: var(--header-text); text-decoration: none; }

.banner-title {
  margin: 0;
  font-size: 28px;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.18;
  color: var(--header-text);
}
.banner-subtitle {
  margin: 4px 0 0;
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--header-mute);
  font-weight: 500;
}

.banner-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 7px 12px;
  border-radius: 8px;
  color: var(--header-soft);
  font-size: 14px;
  font-weight: 500;
  white-space: nowrap;
  transition: color .15s ease, background-color .15s ease;
}
.banner-link:hover {
  background: rgba(255, 255, 255, 0.08);
  color: var(--header-text);
  text-decoration: none;
}
.banner-link.is-active {
  background: rgba(255, 255, 255, 0.14);
  color: var(--header-text);
}
.rss-link svg { width: 13.5px; height: 13.5px; }

/* 标题栏内联搜索框 */
.header-search { position: relative; display: flex; align-items: center; }
.header-search > svg {
  position: absolute;
  left: 13px;
  width: 15px;
  height: 15px;
  color: var(--header-mute);
  pointer-events: none;
  transition: color .2s ease;
}
.header-search:focus-within > svg { color: var(--header-focus); }
.header-search-input {
  width: 212px;
  padding: 9px 14px 9px 38px;
  border: 1px solid var(--header-line);
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.07);
  color: var(--header-text);
  font-size: 14px;
  font-family: inherit;
  line-height: 1.45;
  outline: none;
  transition: width .25s ease, background-color .2s ease,
    border-color .2s ease, box-shadow .2s ease;
}
.header-search-input::placeholder { color: var(--header-mute); }
.header-search-input:hover {
  background: rgba(255, 255, 255, 0.11);
  border-color: rgba(255, 255, 255, 0.18);
}
.header-search-input:focus {
  width: 272px;
  background: rgba(255, 255, 255, 0.13);
  border-color: var(--header-focus);
  box-shadow: 0 0 0 3px rgba(90, 162, 255, 0.25);
}
.header-search-input::-webkit-search-cancel-button,
.header-search-input::-webkit-search-decoration { -webkit-appearance: none; appearance: none; }

/* 主题切换按钮 */
.theme-toggle {
  width: 34px;
  height: 34px;
  display: grid;
  place-items: center;
  padding: 0;
  border: 1px solid var(--header-line);
  border-radius: 9px;
  background: rgba(255, 255, 255, 0.05);
  color: var(--header-soft);
  cursor: pointer;
  transition: color .15s ease, background-color .15s ease, border-color .15s ease;
}
.theme-toggle svg { width: 15px; height: 15px; }
.theme-toggle:hover {
  color: var(--header-text);
  background: rgba(255, 255, 255, 0.12);
  border-color: rgba(255, 255, 255, 0.22);
}
.theme-toggle:focus-visible { outline: 2px solid var(--header-focus); outline-offset: 2px; }
[data-theme="dark"] .ico-sun { display: none; }
html:not([data-theme="dark"]) .ico-moon { display: none; }

/* 搜索页：居中大号输入框 */
.search-page { max-width: 780px; margin: 0 auto; }
.search-page .search-form.is-page { margin: 8px 0 26px; }
.search-input.is-wide {
  width: 100%;
  padding: 13px 18px;
  border: 1px solid var(--border);
  border-radius: 12px;
  font-size: 15.5px;
  font-family: inherit;
  color: var(--text);
  background: var(--card);
  outline: none;
  transition: border-color .2s ease, box-shadow .2s ease;
}
.search-input.is-wide::placeholder { color: var(--text-mute); }
.search-input.is-wide:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}
.search-results .post-card { margin-bottom: 18px; }

/* ============================================================
   布局
   ============================================================ */
.layout {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 32px 24px 64px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 40px;
  align-items: start;
}
.layout-single { grid-template-columns: minmax(0, 1fr); }

.sidebar { position: sticky; top: 84px; }
.sidebar-inner { display: flex; flex-direction: column; gap: 20px; }

/* ============================================================
   卡片
   ============================================================ */
.card {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}

.card-title {
  margin: 0 0 12px;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
}
.card-title::before {
  content: "";
  width: 3px;
  height: 14px;
  border-radius: 2px;
  background: var(--accent);
}

.card-foot-note { margin: 12px 0 0; font-size: 12.5px; color: var(--text-mute); }

/* 可折叠侧栏卡片（归档 / 分类）：整张卡即 <details> */
.collapse-card { padding: 0; overflow: hidden; }
.collapse-card > summary.card-head {
  list-style: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 18px;
  margin: 0;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: .04em;
  color: var(--text);
  user-select: none;
}
.collapse-card > summary.card-head::-webkit-details-marker { display: none; }
.collapse-card > summary.card-head::before {
  content: "";
  width: 3px;
  height: 14px;
  border-radius: 2px;
  background: var(--accent);
}
.collapse-card > summary.card-head::after {
  content: "▸";
  margin-left: auto;
  color: var(--text-mute);
  transition: transform .2s ease;
  font-size: 12px;
}
.collapse-card[open] > summary.card-head::after { content: "▾"; }
.collapse-card > .card-body { padding: 0 18px 18px; }
.collapse-card .card-foot-note { padding: 0 18px 18px; margin-top: 10px; }

/* 近期文章 / 归档 / 分类 列表 */
.recent-list, .archive-list, .category-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

/* 归档 / 分类：默认最多露出 6 项，超出部分滚动查看 */
.collapse-card .item-link { line-height: 20px; }
.archive-list, .category-list {
  max-height: 214px; /* 6 项：6×(20 行高 + 7×2 内距) + 5×2 间距 */
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}
.archive-list::-webkit-scrollbar,
.category-list::-webkit-scrollbar { width: 6px; }
.archive-list::-webkit-scrollbar-thumb,
.category-list::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
.archive-list::-webkit-scrollbar-track,
.category-list::-webkit-scrollbar-track { background: transparent; }

.item-link {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 7px 8px;
  border-radius: 8px;
  color: var(--text-soft);
  font-size: 13.5px;
  line-height: 1.5;
}
.item-link:hover { background: var(--bg-soft); color: var(--accent); text-decoration: none; }
.item-date {
  font-size: 11.5px;
  color: var(--text-mute);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
  min-width: 38px;
}
.item-text { flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.item-count {
  font-size: 11.5px;
  color: var(--text-mute);
  background: var(--bg-soft);
  border-radius: 10px;
  padding: 0 7px;
  flex-shrink: 0;
}

/* 标签云 */
.tag-cloud { display: flex; flex-wrap: wrap; gap: 7px; }

/* 侧栏标签云：默认最多 6 行，超出滚动（整页 is-page 标签云不受影响） */
.sidebar-inner .tag-cloud .tag-chip { line-height: 20px; }
.sidebar-inner .tag-cloud {
  max-height: 215px; /* 6 行：6×(20 行高 + 8 内距 + 2 边框) + 5×7 行距 */
  overflow-y: auto;
  overscroll-behavior: contain;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}
.sidebar-inner .tag-cloud::-webkit-scrollbar { width: 6px; }
.sidebar-inner .tag-cloud::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
.sidebar-inner .tag-cloud::-webkit-scrollbar-track { background: transparent; }
.tag-chip {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 4px 10px;
  border-radius: 14px;
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  color: var(--text-soft);
  font-size: 12.5px;
  transition: all .15s ease;
}
.tag-chip:hover {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
  transform: translateY(-1px);
}
.tag-count {
  font-size: 11px;
  color: var(--text-mute);
  font-variant-numeric: tabular-nums;
}
.tag-chip.is-large { padding: 7px 14px; font-size: 14px; border-radius: 18px; }

/* ============================================================
   页面标题 / 文章卡片
   ============================================================ */
.page-head { margin-bottom: 24px; }
.page-title {
  margin: 0 0 6px;
  font-size: 26px;
  line-height: 1.3;
  letter-spacing: -.01em;
}
.page-subtitle { margin: 0; color: var(--text-mute); font-size: 14px; }

.post-card {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-bottom: 16px;
  box-shadow: var(--shadow);
  transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}
.post-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
  border-color: var(--border);
}

.card-meta {
  display: flex;
  align-items: center;
  gap: 7px;
  font-size: 12.5px;
  color: var(--text-mute);
  margin-bottom: 8px;
}
.card-cat { color: var(--accent); font-weight: 600; }
.card-cat:hover { text-decoration: underline; }
.dot { color: var(--border); }

.card-title {
  margin: 0 0 10px;
  font-size: 19px;
  line-height: 1.45;
}
.card-title a { color: var(--text); }
.card-title a:hover { color: var(--accent); text-decoration: none; }

.card-summary {
  margin: 0 0 14px;
  color: var(--text-soft);
  font-size: 14.5px;
  line-height: 1.75;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-foot { display: flex; align-items: center; flex-wrap: wrap; gap: 8px; }
.card-tag {
  font-size: 12px;
  color: var(--text-mute);
  padding: 2px 8px;
  border-radius: 6px;
  background: var(--bg-soft);
}
.card-tag:hover { color: var(--accent); text-decoration: none; }
.card-more { margin-left: auto; font-size: 13px; }

/* ============================================================
   文章详情
   ============================================================ */
/* 目录卡片：位于右侧栏顶部，随侧栏 sticky 固定，不遮挡正文 */
.toc-card { font-size: 13px; }
.toc-scroll { max-height: calc(100vh - 260px); overflow-y: auto; }
.toc-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 2px; }
.toc-item a {
  display: block;
  padding: 4px 8px;
  border-radius: 6px;
  color: var(--text-mute);
  line-height: 1.5;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.toc-item a:hover { background: var(--bg-soft); color: var(--accent); text-decoration: none; }
.toc-item.is-active a { color: var(--accent); background: var(--accent-soft); font-weight: 600; }
.toc-l3 a { padding-left: 20px; font-size: 12.5px; }

.post-article {
  background: var(--card);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 32px 36px;
  box-shadow: var(--shadow);
}

.post-head { margin-bottom: 24px; padding-bottom: 18px; border-bottom: 1px solid var(--border-soft); }
.post-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  font-size: 13px;
  color: var(--text-mute);
  margin-bottom: 10px;
}
.post-cat { color: var(--accent); font-weight: 600; }
.post-title { margin: 0; font-size: 30px; line-height: 1.35; letter-spacing: -.01em; }

.post-tags { margin-top: 28px; display: flex; flex-wrap: wrap; gap: 8px; }
.post-tag {
  padding: 4px 10px;
  border-radius: 14px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 12.5px;
}
.post-tag:hover { text-decoration: none; filter: brightness(1.08); }

.post-nav {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
  margin-top: 22px;
}
.nav-post {
  padding: 14px 16px;
  border: 1px solid var(--border-soft);
  border-radius: 10px;
  background: var(--card);
  color: var(--text-soft);
  font-size: 13.5px;
  line-height: 1.6;
}
a.nav-post:hover { color: var(--accent); border-color: var(--accent); text-decoration: none; }
.nav-post.next { text-align: right; }
.nav-post.is-empty { color: var(--text-mute); font-size: 13px; text-align: center; }

.related-block { margin-top: 36px; }
.section-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-soft);
  margin-bottom: 12px;
}

/* ============================================================
   Markdown 正文
   ============================================================ */
.markdown-body { font-size: 15.8px; line-height: 1.85; word-wrap: break-word; }
.markdown-body > *:first-child { margin-top: 0; }
.markdown-body h1, .markdown-body h2, .markdown-body h3, .markdown-body h4 {
  margin: 1.9em 0 .8em;
  line-height: 1.4;
  font-weight: 700;
  scroll-margin-top: 90px;
}
.markdown-body h1 { font-size: 25px; }
.markdown-body h2 {
  font-size: 21px;
  padding-bottom: .3em;
  border-bottom: 1px solid var(--border-soft);
}
.markdown-body h3 { font-size: 17.5px; }
.markdown-body h4 { font-size: 15.5px; }

.markdown-body p { margin: 1em 0; }
.markdown-body ul, .markdown-body ol { padding-left: 1.5em; margin: 1em 0; }
.markdown-body li { margin: .35em 0; }
.markdown-body li > ul, .markdown-body li > ol { margin: .3em 0; }

.markdown-body blockquote {
  margin: 1.3em 0;
  padding: 2px 16px;
  border-left: 3px solid var(--accent);
  background: var(--bg-soft);
  color: var(--text-soft);
  border-radius: 0 8px 8px 0;
}
.markdown-body blockquote p { margin: .7em 0; }

.markdown-body hr { margin: 2em 0; border: 0; border-top: 1px solid var(--border-soft); }

.markdown-body code {
  padding: .15em .4em;
  background: var(--code-bg);
  border: 1px solid var(--border-soft);
  border-radius: 5px;
  font-family: "JetBrains Mono", "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: .88em;
}

.markdown-body pre {
  position: relative;
  margin: 1.4em 0;
  padding: 16px 18px;
  background: var(--code-bg);
  border: 1px solid var(--border-soft);
  border-radius: 10px;
  overflow-x: auto;
  line-height: 1.65;
}
.markdown-body pre code {
  padding: 0;
  background: none;
  border: 0;
  font-size: 13.6px;
}

.markdown-body table {
  width: 100%;
  margin: 1.5em 0;
  border-collapse: collapse;
  font-size: 14.5px;
  display: block;
  overflow-x: auto;
}
.markdown-body th, .markdown-body td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
.markdown-body th { background: var(--bg-soft); font-weight: 600; }
.markdown-body tr:nth-child(2n) td { background: var(--bg-soft); }

.markdown-body .admonition,
.markdown-body .admonition details {
  margin: 1.5em 0;
  padding: 14px 16px;
  border-radius: 10px;
  background: var(--bg-soft);
  border: 1px solid var(--border-soft);
  border-left: 3px solid var(--accent);
}
.markdown-body .admonition-title {
  font-weight: 700;
  margin: 0 0 6px;
  color: var(--text);
}
.markdown-body .admonition.note { border-left-color: #2f6feb; }
.markdown-body .admonition.warning { border-left-color: #d29922; }
.markdown-body .admonition.danger { border-left-color: #cf222e; }
.markdown-body .admonition p:last-child { margin-bottom: 0; }

.markdown-body .task-list-item { list-style: none; margin-left: -1.2em; }
.markdown-body input[type="checkbox"] { margin-right: 6px; }

.markdown-body .headerlink, .markdown-body .anchor {
  opacity: 0;
  margin-left: 8px;
  font-size: .85em;
  color: var(--text-mute);
  text-decoration: none;
  transition: opacity .15s ease;
}
.markdown-body h1:hover .anchor,
.markdown-body h2:hover .anchor,
.markdown-body h3:hover .anchor { opacity: 1; }

/* 代码复制按钮 */
.copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  padding: 3px 9px;
  font-size: 11.5px;
  color: var(--text-mute);
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 6px;
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s ease;
}
.markdown-body pre:hover .copy-btn { opacity: 1; }
.copy-btn:hover { color: var(--accent); border-color: var(--accent); }

/* ============================================================
   归档 / 分类 / 分页 / 404
   ============================================================ */
.year-block { margin-bottom: 28px; }
.year-title {
  margin: 0 0 10px;
  font-size: 20px;
  font-variant-numeric: tabular-nums;
  color: var(--text);
}

.cat-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 14px; }
.cat-card {
  display: block;
  padding: 18px;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  background: var(--card);
  box-shadow: var(--shadow);
  transition: transform .18s ease, border-color .18s ease;
}
.cat-card:hover { transform: translateY(-2px); border-color: var(--accent); text-decoration: none; }
.cat-name { font-size: 16px; font-weight: 700; color: var(--text); }
.cat-desc { margin: 6px 0 0; font-size: 13px; color: var(--text-soft); }
.cat-count { display: inline-block; margin-top: 10px; font-size: 12px; color: var(--text-mute); }

.pager { display: flex; justify-content: center; align-items: center; gap: 6px; margin: 32px 0 8px; flex-wrap: wrap; }
.page-btn {
  min-width: 36px;
  height: 36px;
  padding: 0 12px;
  display: inline-grid;
  place-items: center;
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text-soft);
  font-size: 14px;
  background: var(--card);
}
a.page-btn:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.page-btn.is-current { background: var(--accent); border-color: var(--accent); color: #fff; font-weight: 600; }
.page-dots { color: var(--text-mute); padding: 0 4px; }

.empty-state {
  padding: 48px 24px;
  text-align: center;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  background: var(--card);
}

.notfound { text-align: center; padding: 60px 20px; }
.notfound .code { font-size: 64px; font-weight: 800; color: var(--accent); line-height: 1; }
.notfound p { color: var(--text-soft); margin: 16px 0 22px; }
.btn {
  display: inline-block;
  padding: 9px 20px;
  border-radius: 8px;
  background: var(--accent);
  color: #fff;
}
.btn:hover { color: #fff; text-decoration: none; filter: brightness(1.08); }

/* ============================================================
   页脚
   ============================================================ */
.site-footer {
  border-top: 1px solid var(--border-soft);
  background: var(--bg-soft);
  margin-top: 40px;
}
.footer-inner { max-width: var(--maxw); margin: 0 auto; padding: 28px 24px; text-align: center; }
.footer-line { margin: 4px 0; font-size: 13.5px; color: var(--text-soft); }

/* 返回顶部 */
.to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text-soft);
  cursor: pointer;
  box-shadow: var(--shadow);
  display: none;
  place-items: center;
  font-size: 16px;
}
.to-top.show { display: grid; }
.to-top:hover { color: var(--accent); border-color: var(--accent); }

/* ============================================================
   响应式
   ============================================================ */
@media (max-width: 1000px) {
  .layout { grid-template-columns: minmax(0, 1fr); }
  .sidebar { position: static; }
  .toc-scroll { max-height: none; }
}

@media (max-width: 720px) {
  .banner-inner {
    grid-template-columns: 1fr;
    grid-template-rows: auto auto auto;
    gap: 10px;
    padding: 14px 16px;
    min-height: 0;
  }
  .banner-left, .banner-right { justify-content: center; }
  .banner-right { flex-wrap: wrap; }
  .header-search { flex: 1 1 auto; width: 100%; max-width: 340px; }
  .header-search-input,
  .header-search-input:focus { width: 100%; }
  .banner-title { font-size: 24px; }
  .banner-subtitle { font-size: 11px; }
  .layout { padding: 20px 16px 48px; }
  .post-article { padding: 22px 18px; }
  .post-title { font-size: 24px; }
  .post-nav { grid-template-columns: 1fr; }
  .nav-post.next { text-align: left; }
  .markdown-body { font-size: 15.2px; }
}