/* ==========================================================================
   博发真人会馆 · 共享样式 /assets/site.css
   会馆档案室：暖白阅读面 + 深墨蓝轨道 + 浅砂分层 + 朱砂橙／松石绿状态
   ========================================================================== */

/* --- 1. 基础重置 --------------------------------------------------------- */
*,
*::before,
*::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--topbar-h) + var(--hint-h) + 16px);
}

body,
h1, h2, h3, h4, h5,
p, ol, ul, figure, blockquote, dl, dd { margin: 0; }

ol, ul { padding: 0; list-style: none; }

img, svg, video { display: block; max-width: 100%; }

button {
  font: inherit;
  color: inherit;
  background: none;
  border: 0;
  padding: 0;
  cursor: pointer;
}

a { color: inherit; text-decoration: none; }

table { border-collapse: collapse; width: 100%; }

/* --- 2. 变量 ------------------------------------------------------------- */
:root {
  /* 矿物色体系 */
  --c-mist: #6E8091;        /* 晨雾灰蓝 */
  --c-ink: #1E2A38;         /* 深墨蓝 */
  --c-warm: #F7F3EC;        /* 暖白 */
  --c-sand: #EDE3D3;        /* 浅砂 */
  --c-cinnabar: #B84A22;    /* 朱砂橙 */
  --c-cinnabar-lt: #D9713F;
  --c-turquoise: #2F6F62;   /* 松石绿 */
  --c-turquoise-lt: #7FBFAE;
  --c-terracotta: #A96B4A;  /* 陶土 */
  --c-moss: #6B7A4F;        /* 苔绿 */
  --c-stone: #8A8F8C;       /* 岩灰 */

  --text-sub: #4C5967;

  /* 线条 */
  --rule: rgba(30, 42, 56, 0.16);
  --rule-strong: rgba(30, 42, 56, 0.34);
  --rule-dark: rgba(247, 243, 236, 0.16);

  /* 纸张纤维底纹 */
  --paper:
    repeating-linear-gradient(90deg, rgba(30, 42, 56, 0.030) 0 1px, transparent 1px 4px),
    repeating-linear-gradient(0deg, rgba(30, 42, 56, 0.020) 0 1px, transparent 1px 6px);

  /* 字体 */
  --font-serif: "Noto Serif SC", "Source Han Serif SC", "Songti SC", "SimSun", serif;
  --font-sans: "Noto Sans SC", "Source Han Sans SC", "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", "Sarasa Mono SC", ui-monospace, SFMono-Regular, Consolas, monospace;

  /* 字号阶梯 12 / 14 / 16 / 20 / 28 / 36 / 44 */
  --fs-12: 0.75rem;
  --fs-14: 0.875rem;
  --fs-16: 1rem;
  --fs-20: 1.25rem;
  --fs-28: 1.75rem;
  --fs-36: 2.25rem;
  --fs-44: 2.75rem;

  /* 结构 */
  --rail-w: 208px;
  --hint-h: 42px;
  --topbar-h: 58px;
}

/* --- 3. 正文与排版 ------------------------------------------------------- */
body {
  background-color: var(--c-warm);
  background-image: var(--paper);
  color: var(--c-ink);
  font-family: var(--font-sans);
  font-size: var(--fs-16);
  line-height: 1.85;
  font-weight: 400;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  font-family: var(--font-serif);
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: 0.01em;
}

h1 { font-size: clamp(var(--fs-28), 4.6vw, var(--fs-44)); }
h2 { font-size: clamp(1.375rem, 3.2vw, var(--fs-28)); }
h3 { font-size: var(--fs-20); font-weight: 600; }
h4 { font-size: var(--fs-16); font-weight: 600; }

.mono,
.num,
[data-num] {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.04em;
}

.num { color: var(--c-mist); }

.eyebrow {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.2em;
  color: var(--c-mist);
  text-transform: uppercase;
}

.lede {
  font-family: var(--font-serif);
  font-size: clamp(1.0625rem, 2.4vw, 1.375rem);
  line-height: 1.75;
  color: var(--c-ink);
}

.prose {
  max-width: 36em;
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--c-ink);
}

.prose p + p,
.prose ul + p,
.prose p + ul { margin-top: 1.1em; }

.prose ul { max-width: 36em; }
.prose li {
  position: relative;
  padding-left: 1.1em;
  margin-top: 0.5em;
}
.prose li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.86em;
  width: 6px;
  height: 1px;
  background: var(--c-terracotta);
}

.rule {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: 28px 0;
}

.note {
  border-left: 3px solid var(--c-sand);
  padding: 4px 0 4px 14px;
  font-size: var(--fs-14);
  line-height: 1.75;
  color: var(--text-sub);
}

.note--version {
  border-left-color: var(--c-terracotta);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.05em;
  font-variant-numeric: tabular-nums;
  color: var(--text-sub);
}

/* --- 4. 布局容器 --------------------------------------------------------- */
.shell {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 20px;
}

.section { padding: 40px 0; }

.section--sand { background-color: var(--c-sand); }
.section--mist { background-color: rgba(110, 128, 145, 0.13); }
.section--ink {
  background-color: var(--c-ink);
  color: var(--c-warm);
}
.section--ink .section-head__line,
.section--ink .note { color: rgba(247, 243, 236, 0.72); }
.section--ink .section-head { border-bottom-color: var(--rule-dark); }
.section--ink .section-head__index { color: var(--c-cinnabar-lt); }

.grid { display: grid; gap: 20px; }
.grid--2 { grid-template-columns: 1fr; }
.grid--3 { grid-template-columns: 1fr; }
.grid--doc { grid-template-columns: 1fr; }

.section-head {
  display: grid;
  gap: 10px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--rule-strong);
  margin-bottom: 24px;
}

.section-head__index {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.18em;
  color: var(--c-cinnabar);
  font-variant-numeric: tabular-nums;
}

.section-head__title {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: clamp(1.375rem, 3vw, var(--fs-28));
}

.section-head__line {
  font-size: var(--fs-14);
  line-height: 1.8;
  color: var(--text-sub);
  max-width: 46em;
}

/* --- 5. 组件 ------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border: 1px solid var(--c-ink);
  background: transparent;
  color: var(--c-ink);
  font-size: var(--fs-14);
  line-height: 1.4;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}

.btn:hover { background: var(--c-ink); color: var(--c-warm); }

.btn--solid {
  background: var(--c-cinnabar);
  border-color: var(--c-cinnabar);
  color: var(--c-warm);
}
.btn--solid:hover { background: #9C3D1B; border-color: #9C3D1B; color: var(--c-warm); }

.btn--ghost {
  border-color: var(--rule-strong);
  color: var(--c-mist);
}
.btn--ghost:hover { background: var(--c-mist); border-color: var(--c-mist); color: var(--c-warm); }

.btn--mono {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.08em;
}

.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 9px;
  border: 1px solid currentColor;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.06em;
  line-height: 1.6;
  font-variant-numeric: tabular-nums;
  color: var(--c-mist);
}
.tag--cinnabar { color: var(--c-cinnabar); }
.tag--turquoise { color: var(--c-turquoise); }
.tag--moss { color: var(--c-moss); }
.tag--clay { color: var(--c-terracotta); }
.tag--stone { color: var(--c-stone); }

.card {
  position: relative;
  background: var(--c-warm);
  border: 1px solid var(--rule-strong);
  padding: 20px 22px 22px;
}
.card::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: 0;
  width: 16px;
  height: 16px;
  background: var(--c-warm);
  border-top: 1px solid var(--rule-strong);
  border-left: 1px solid var(--rule-strong);
  clip-path: polygon(100% 0, 100% 100%, 0 100%);
}

.card__head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px;
  padding-bottom: 10px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--rule);
}

.card__title {
  font-family: var(--font-serif);
  font-size: var(--fs-20);
  font-weight: 600;
  line-height: 1.4;
}

.card__list { display: grid; gap: 8px; }
.card__list li {
  position: relative;
  padding-left: 1.05em;
  font-size: var(--fs-14);
  line-height: 1.75;
  color: var(--text-sub);
}
.card__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.82em;
  width: 5px;
  height: 1px;
  background: var(--c-moss);
}

.breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.04em;
  color: var(--c-stone);
}
.breadcrumbs__item::after {
  content: "/";
  margin-left: 8px;
  color: var(--rule-strong);
}
.breadcrumbs__item:last-child::after { content: ""; }
.breadcrumbs__item a:hover { color: var(--c-cinnabar); }

.table-wrap {
  width: 100%;
  overflow-x: auto;
  border: 1px solid var(--rule);
  background: var(--c-warm);
}

.data-table {
  width: 100%;
  font-size: var(--fs-14);
}
.data-table th,
.data-table td {
  text-align: left;
  padding: 12px 14px;
  border-bottom: 1px solid var(--rule);
  vertical-align: top;
  line-height: 1.7;
}
.data-table thead th {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.08em;
  color: var(--c-mist);
  border-bottom: 1px solid var(--rule-strong);
  white-space: nowrap;
}
.data-table tbody tr:hover { background: rgba(237, 227, 211, 0.55); }
.data-table tbody tr:last-child td { border-bottom: 0; }

.figure { margin: 0; }

.figure__frame {
  position: relative;
  border: 1px solid var(--rule-strong);
  background-color: var(--c-sand);
  background-image: var(--paper);
  overflow: hidden;
}
.figure__frame::after {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1px solid rgba(247, 243, 236, 0.55);
  pointer-events: none;
}

.figure__img {
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  background: var(--c-mist);
  color: transparent;
}
.figure--portrait .figure__img { aspect-ratio: 3 / 4; }
.figure--wide .figure__img { aspect-ratio: 16 / 9; }

.figure__caption {
  margin-top: 10px;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  line-height: 1.65;
  letter-spacing: 0.03em;
  color: var(--c-stone);
}

.fold {
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}
.fold__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  width: 100%;
  padding: 14px 0;
  text-align: left;
  font-family: var(--font-serif);
  font-size: var(--fs-16);
  font-weight: 600;
  color: var(--c-ink);
}
.fold__head::after {
  content: "＋";
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--fs-14);
  color: var(--c-cinnabar);
}
.fold__head[aria-expanded="true"]::after { content: "－"; }
.fold__head:hover { color: var(--c-cinnabar); }
.fold__body { padding: 0 0 18px; }

.to-top {
  position: fixed;
  right: 18px;
  bottom: 18px;
  z-index: 55;
  padding: 9px 14px;
  border: 1px solid var(--c-ink);
  background: var(--c-ink);
  color: var(--c-warm);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.08em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0s linear 0.2s, background-color 0.18s ease;
}
.to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: none;
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0s, background-color 0.18s ease;
}
.to-top:hover {
  background: var(--c-cinnabar);
  border-color: var(--c-cinnabar);
}

/* --- 6. 焦点与主内容偏移 ------------------------------------------------ */
:focus-visible {
  outline: 2px solid var(--c-cinnabar);
  outline-offset: 2px;
}
.site-header :focus-visible,
.site-footer :focus-visible,
.to-top:focus-visible {
  outline-color: var(--c-cinnabar-lt);
}

#main-content {
  margin-left: 0;
  padding-top: calc(var(--topbar-h) + var(--hint-h));
  outline: none;
}

/* --- 7. 头部：移动端顶部条 + 抽屉 --------------------------------------- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 60;
  background: var(--c-ink);
  color: var(--c-warm);
  border-bottom: 1px solid var(--rule-dark);
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 200;
  padding: 8px 14px;
  background: var(--c-warm);
  color: var(--c-ink);
  border: 1px solid var(--c-cinnabar);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.06em;
  transform: translateY(-180%);
  transition: transform 0.18s ease;
}
.skip-link:focus { transform: translateY(0); }

.rail-top {
  position: relative;
  z-index: 4;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  height: var(--topbar-h);
  padding: 0 14px;
}

.brand { display: flex; align-items: center; gap: 10px; min-width: 0; }

.brand__mark {
  display: grid;
  place-items: center;
  flex: none;
  width: 34px;
  height: 34px;
  border: 1px solid rgba(247, 243, 236, 0.34);
  background: rgba(247, 243, 236, 0.07);
  font-family: var(--font-serif);
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--c-warm);
}

.brand__text { display: flex; flex-direction: column; min-width: 0; }

.brand__name {
  font-family: var(--font-serif);
  font-size: 1rem;
  font-weight: 700;
  line-height: 1.3;
  letter-spacing: 0.02em;
  white-space: nowrap;
}

.brand__sub {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.1em;
  line-height: 1.4;
  color: var(--c-stone);
  white-space: nowrap;
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  flex: none;
  padding: 8px 12px;
  border: 1px solid rgba(247, 243, 236, 0.3);
  color: var(--c-warm);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.1em;
}
.nav-toggle:hover { border-color: var(--c-cinnabar-lt); color: var(--c-cinnabar-lt); }

.nav-toggle__bars {
  position: relative;
  width: 16px;
  height: 10px;
}
.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1px;
  background: currentColor;
  transition: transform 0.18s ease;
}
.nav-toggle__bars::before { top: 0; }
.nav-toggle__bars::after { bottom: 0; }
.site-header[data-open] .nav-toggle__bars::before { transform: translateY(4.5px) rotate(45deg); }
.site-header[data-open] .nav-toggle__bars::after { transform: translateY(-4.5px) rotate(-45deg); }

.nav-scrim {
  position: fixed;
  inset: 0;
  z-index: 2;
  background: rgba(30, 42, 56, 0.5);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease;
}
.site-header[data-open] .nav-scrim {
  opacity: 1;
  pointer-events: auto;
}

.nav {
  position: fixed;
  top: var(--topbar-h);
  bottom: 0;
  left: 0;
  z-index: 3;
  display: flex;
  flex-direction: column;
  width: min(320px, 84vw);
  padding: 8px 0 20px;
  background: var(--c-ink);
  border-right: 1px solid var(--rule-dark);
  overflow-y: auto;
  transform: translateX(-102%);
  visibility: hidden;
  transition: transform 0.2s ease, visibility 0s linear 0.2s;
}
.site-header[data-open] .nav {
  transform: translateX(0);
  visibility: visible;
  transition: transform 0.2s ease, visibility 0s;
}

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

.nav__item { border-bottom: 1px solid rgba(247, 243, 236, 0.08); }

.nav__link {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  align-items: baseline;
  gap: 8px;
  padding: 11px 18px;
  border-left: 3px solid transparent;
  font-size: 0.9375rem;
  line-height: 1.5;
  color: rgba(247, 243, 236, 0.82);
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}
.nav__link:hover {
  background: rgba(247, 243, 236, 0.06);
  color: #FFFFFF;
}
.nav__link[aria-current="page"] {
  background: rgba(184, 74, 34, 0.2);
  border-left-color: var(--c-cinnabar);
  color: #FFFFFF;
}

.nav__num {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.08em;
  color: var(--c-stone);
  font-variant-numeric: tabular-nums;
}
.nav__link[aria-current="page"] .nav__num { color: var(--c-cinnabar-lt); }

.nav__label { min-width: 0; }

.rail-tools {
  margin-top: auto;
  padding: 18px;
  border-top: 1px solid var(--rule-dark);
}

.rail-tools__title {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.18em;
  color: var(--c-stone);
  margin-bottom: 10px;
}

.rail-tools__list {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-bottom: 12px;
}

.rail-tool {
  display: block;
  width: 100%;
  padding: 7px 0;
  border-bottom: 1px dashed rgba(247, 243, 236, 0.16);
  text-align: left;
  font-size: var(--fs-14);
  line-height: 1.6;
  color: rgba(247, 243, 236, 0.78);
  transition: color 0.18s ease;
}
.rail-tool:hover { color: #FFFFFF; }

.rail-tool--button {
  border-bottom-style: solid;
  border-bottom-color: rgba(247, 243, 236, 0.28);
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.06em;
}
.rail-tool--button[aria-pressed="true"] { color: var(--c-turquoise-lt); }

.hint-bar {
  position: fixed;
  top: var(--topbar-h);
  left: 0;
  right: 0;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 12px;
  height: var(--hint-h);
  padding: 0 14px;
  background: var(--c-sand);
  color: var(--c-ink);
  border-bottom: 1px solid var(--rule-strong);
  overflow: hidden;
}

.hint-bar__text {
  flex: 1 1 auto;
  min-width: 0;
  font-size: var(--fs-12);
  line-height: 1.4;
  color: var(--text-sub);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.hint-bar__action {
  flex: none;
  padding: 5px 12px;
  border: 1px solid var(--c-ink);
  background: transparent;
  color: var(--c-ink);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.06em;
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease;
}
.hint-bar__action:hover { background: var(--c-ink); color: var(--c-warm); }
.hint-bar__action[aria-pressed="true"] {
  background: var(--c-turquoise);
  border-color: var(--c-turquoise);
  color: #FFFFFF;
}

.hint-bar__progress {
  position: absolute;
  left: 0;
  bottom: 0;
  height: 2px;
  width: 0;
  background: var(--c-cinnabar);
  transition: width 0.12s linear;
}

/* --- 8. 页脚 ------------------------------------------------------------- */
.site-footer {
  margin-left: 0;
  padding: 42px 0 24px;
  background: var(--c-ink);
  color: rgba(247, 243, 236, 0.82);
  border-top: 1px solid var(--rule-dark);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 28px;
}

.footer-brand__name {
  font-family: var(--font-serif);
  font-size: var(--fs-20);
  font-weight: 700;
  color: var(--c-warm);
  line-height: 1.4;
}

.footer-brand__line {
  margin-top: 6px;
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.1em;
  color: var(--c-stone);
}

.footer-brand__note {
  margin-top: 12px;
  max-width: 24em;
  font-size: var(--fs-14);
  line-height: 1.75;
  color: rgba(247, 243, 236, 0.62);
}

.footer-col__title {
  padding-bottom: 10px;
  margin-bottom: 10px;
  border-bottom: 1px solid var(--rule-dark);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.16em;
  color: rgba(247, 243, 236, 0.56);
}

.footer-col__list { display: flex; flex-direction: column; }

.footer-col__link {
  display: inline-block;
  padding: 5px 0;
  font-size: 0.9375rem;
  line-height: 1.6;
  color: rgba(247, 243, 236, 0.82);
  transition: color 0.18s ease;
}
.footer-col__link:hover {
  color: var(--c-cinnabar-lt);
  text-decoration: underline;
  text-underline-offset: 4px;
}

.footer-meta {
  display: grid;
  grid-template-columns: 1fr;
  gap: 6px;
  margin-top: 34px;
  padding-top: 18px;
  border-top: 1px dashed var(--rule-dark);
}

.footer-meta__item {
  font-family: var(--font-mono);
  font-size: var(--fs-12);
  letter-spacing: 0.04em;
  line-height: 1.8;
  color: rgba(247, 243, 236, 0.68);
  font-variant-numeric: tabular-nums;
}

.footer-meta__note {
  margin-top: 6px;
  max-width: 40em;
  font-size: var(--fs-12);
  line-height: 1.8;
  color: var(--c-stone);
}

.footer-legal {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 20px;
  justify-content: space-between;
  margin-top: 22px;
  padding-top: 14px;
  border-top: 1px solid var(--rule-dark);
}

.footer-legal__item {
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.06em;
  color: var(--c-stone);
}

/* --- 9. 断点：平板与桌面 ------------------------------------------------- */
@media (min-width: 640px) {
  .shell { padding: 0 32px; }
  .section { padding: 56px 0; }
  .grid { gap: 24px; }
  .hint-bar { padding: 0 20px; }
  .hint-bar__text { font-size: var(--fs-14); }
  .footer-meta { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 768px) {
  .grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: 1.5fr 1fr 1fr 1fr; gap: 32px; }
  .rail-top { padding: 0 20px; }
}

@media (min-width: 1024px) {
  html { scroll-padding-top: calc(var(--hint-h) + 20px); }

  #main-content {
    margin-left: var(--rail-w);
    padding-top: var(--hint-h);
  }

  .site-header {
    right: auto;
    bottom: 0;
    width: var(--rail-w);
    border-bottom: 0;
    border-right: 1px solid var(--rule-dark);
  }

  .rail-top {
    height: auto;
    flex-direction: column;
    align-items: flex-start;
    gap: 18px;
    padding: 26px 18px 20px;
    border-bottom: 1px solid var(--rule-dark);
  }

  .brand__sub { font-size: 0.625rem; }

  .nav-toggle { display: none; }

  .nav {
    position: static;
    transform: none;
    visibility: visible;
    width: auto;
    flex: 1 1 auto;
    padding: 16px 0 0;
    background: transparent;
    border-right: 0;
    overflow: visible;
    transition: none;
  }

  .nav-scrim { display: none; }

  .rail-tools { padding: 18px; }

  .hint-bar {
    top: 0;
    left: var(--rail-w);
    z-index: 1;
    padding: 0 28px;
  }

  .site-footer { margin-left: var(--rail-w); padding: 54px 0 26px; }
  .footer-meta { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .section { padding: 64px 0; }
}

@media (min-width: 1100px) {
  .grid--doc { grid-template-columns: minmax(0, 1fr) 264px; gap: 40px; }
}

@media (min-width: 1280px) {
  .shell { padding: 0 44px; }
}

/* --- 10. 减弱动效 ------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }

  .to-top,
  .to-top.is-visible { transform: none; }
}