/* =========================================================
   /assets/site.css — 12博品牌 共享外壳与基础组件
   结构：reset → 变量 → 基础排版 → 布局工具 → 通用组件
        → 头部 → 页脚 → 响应式 → 动效降级
   ========================================================= */

/* ---------- 1. reset ---------- */
*,
*::before,
*::after { box-sizing: border-box; }

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

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

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

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

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

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

::selection { background: var(--gold-200); color: var(--ink-950); }

/* ---------- 2. 变量 ---------- */
:root {
  --green-900: #12332B;
  --green-700: #1E4A3C;
  --green-500: #2F6B56;
  --gold-500: #D8B56A;
  --gold-200: #F0D9A6;
  --clay-500: #C56B4A;
  --clay-200: #EBC3B3;
  --mist-400: #A9B7BD;
  --paper-100: #F7F3EA;
  --paper-200: #E8E2D5;
  --ink-950: #0E1F1A;

  --rail-w: 256px;
  --note-w: 160px;

  --radius-xl: 28px;
  --radius-lg: 18px;
  --radius-md: 12px;
  --radius-pill: 999px;

  --hair: rgba(18, 51, 43, 0.14);
  --hair-light: rgba(169, 183, 189, 0.26);

  --font-sans: "Source Han Sans SC", "Noto Sans SC", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", -apple-system, BlinkMacSystemFont,
    "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", "JetBrains Mono", ui-monospace, SFMono-Regular,
    Menlo, Consolas, "Liberation Mono", monospace;

  --ease-out: cubic-bezier(0.22, 0.61, 0.36, 1);
  --shadow-soft: 0 14px 34px rgba(18, 51, 43, 0.10);
}

/* ---------- 3. 基础排版 ---------- */
body {
  min-height: 100vh;
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.8;
  letter-spacing: 0.01em;
  color: var(--ink-950);
  background-color: var(--paper-100);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3 {
  color: var(--green-900);
  font-weight: 800;
  letter-spacing: 0.02em;
  line-height: 1.2;
}

h1 { font-size: clamp(2.2rem, 4.8vw, 4.6rem); line-height: 1.12; }
h2 { font-size: clamp(1.6rem, 2.8vw, 2.4rem); }
h3 { font-size: 1.2rem; font-weight: 700; line-height: 1.35; }

p { line-height: 1.85; }

strong { font-weight: 700; color: var(--green-900); }

:focus-visible {
  outline: 3px solid var(--gold-500);
  outline-offset: 3px;
  border-radius: 4px;
}

.mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.01em;
}

/* ---------- 4. 布局工具 ---------- */
.container {
  width: 100%;
  max-width: 1120px;
  margin-inline: auto;
  padding-inline: clamp(20px, 4vw, 44px);
}

.container--narrow { max-width: 820px; }

.section { padding-block: clamp(32px, 5.5vw, 68px); }
.section--tight { padding-block: clamp(22px, 3.5vw, 40px); }

#main-content {
  display: block;
  scroll-margin-top: 88px;
}

.grid {
  display: grid;
  gap: clamp(16px, 2.4vw, 28px);
}

.grid--2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid--3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }

.split {
  display: grid;
  grid-template-columns: 5fr 7fr;
  gap: clamp(20px, 3.5vw, 48px);
  align-items: start;
}

.stack > * + * { margin-top: var(--stack-gap, 1rem); }

.rule {
  height: 1px;
  border: 0;
  background: var(--hair);
}

/* ---------- 5. 排版工具 ---------- */
.display {
  font-size: clamp(2.2rem, 4.8vw, 4.6rem);
  line-height: 1.12;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--green-900);
}

.h2 {
  font-size: clamp(1.6rem, 2.8vw, 2.4rem);
  line-height: 1.2;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--green-900);
}

.h3 {
  font-size: 1.25rem;
  line-height: 1.35;
  font-weight: 700;
  color: var(--green-900);
}

.lead {
  font-size: clamp(1.05rem, 1.6vw, 1.25rem);
  line-height: 1.75;
  color: var(--green-700);
}

.muted { color: var(--green-500); }

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.6em;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--green-500);
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: var(--gold-500);
  flex: none;
}

.prose {
  max-width: 64ch;
  font-size: 1.0625rem;
  line-height: 1.88;
  letter-spacing: 0.01em;
}

.prose p + p { margin-top: 1.1em; }
.prose strong { color: var(--green-900); }

.link-underline {
  position: relative;
  display: inline-block;
  padding-bottom: 2px;
  color: var(--green-700);
  font-weight: 600;
}

.link-underline::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: 1px;
  width: 100%;
  background: var(--gold-500);
  transform: scaleX(0);
  transform-origin: left center;
  transition: transform 0.2s var(--ease-out);
}

.link-underline:hover::after,
.link-underline:focus-visible::after { transform: scaleX(1); }

/* ---------- 6. 通用组件 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.55em;
  padding: 0.8rem 1.35rem;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 0.9375rem;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: 0.03em;
  transition: background-color 0.18s var(--ease-out),
    color 0.18s var(--ease-out), border-color 0.18s var(--ease-out),
    transform 0.18s var(--ease-out);
}

.btn:active { transform: translateY(1px); }

.btn--primary { background: var(--gold-500); color: var(--ink-950); }
.btn--primary:hover { background: var(--gold-200); }

.btn--solid { background: var(--green-700); color: var(--paper-100); }
.btn--solid:hover { background: var(--green-500); }

.btn--ghost {
  background: transparent;
  border-color: var(--mist-400);
  color: var(--green-900);
}
.btn--ghost:hover {
  border-color: var(--gold-500);
  background: rgba(240, 217, 166, 0.35);
}

.btn--sm { padding: 0.55rem 1rem; font-size: 0.8125rem; }

.tag {
  display: inline-flex;
  align-items: center;
  gap: 0.45em;
  padding: 0.28em 0.8em;
  border: 1px solid transparent;
  border-radius: var(--radius-pill);
  font-size: 0.75rem;
  font-weight: 600;
  line-height: 1.6;
  letter-spacing: 0.06em;
  white-space: nowrap;
}

.tag--gold {
  background: var(--gold-200);
  border-color: rgba(216, 181, 106, 0.6);
  color: var(--green-900);
}

.tag--clay {
  background: var(--clay-200);
  border-color: rgba(197, 107, 74, 0.45);
  color: var(--ink-950);
}

.tag--mist {
  background: rgba(169, 183, 189, 0.22);
  border-color: rgba(169, 183, 189, 0.5);
  color: var(--green-700);
}

.tag--outline {
  background: transparent;
  border-color: var(--mist-400);
  color: var(--green-700);
}

/* 索引卡（模块 A） */
.card {
  padding: clamp(20px, 3vw, 32px);
  background: #FFFFFF;
  border: 1px solid var(--paper-200);
  border-radius: var(--radius-xl);
  transition: border-color 0.2s var(--ease-out),
    box-shadow 0.2s var(--ease-out), transform 0.2s var(--ease-out);
}

.card:hover {
  border-color: var(--gold-500);
  box-shadow: var(--shadow-soft);
}

.card--dark {
  background: var(--green-900);
  border-color: rgba(216, 181, 106, 0.28);
  color: rgba(247, 243, 234, 0.84);
}

.card--dark .card__title { color: var(--paper-100); }
.card--dark:hover { border-color: var(--gold-500); }

.card--paper {
  background: var(--paper-100);
  border-color: var(--paper-200);
}

.card__no {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  letter-spacing: 0.12em;
  color: var(--clay-500);
}

.card__title {
  margin-top: 0.5rem;
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.35;
  color: var(--green-900);
}

.card__text {
  margin-top: 0.6rem;
  font-size: 0.9375rem;
  line-height: 1.75;
  color: var(--green-700);
}

.card__foot {
  margin-top: 1.1rem;
  padding-top: 0.85rem;
  border-top: 1px solid var(--hair);
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--green-500);
}

/* 密集索引列表（模块 B） */
.rows {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--hair);
}

.rows > li { border-bottom: 1px solid rgba(18, 51, 43, 0.1); }

.rows a,
.rows .row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 0.4rem 1.2rem;
  padding: 0.9rem 0.3rem;
  transition: background-color 0.18s var(--ease-out),
    color 0.18s var(--ease-out);
}

.rows a:hover { background: rgba(240, 217, 166, 0.35); }

.row__title { font-weight: 600; color: var(--green-900); }

.row__meta {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  color: var(--green-500);
  font-variant-numeric: tabular-nums;
}

/* 图片容器（页面阶段放占位） */
.figure {
  position: relative;
  margin: 0;
  overflow: hidden;
  background: var(--paper-200);
  border: 1px solid rgba(18, 51, 43, 0.1);
  border-radius: var(--radius-xl);
}

.figure__media {
  display: block;
  width: 100%;
  overflow: hidden;
  background: inherit;
}

.figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.figure--wide .figure__media { aspect-ratio: 16 / 9; }
.figure--tall .figure__media { aspect-ratio: 4 / 5; }
.figure--square .figure__media { aspect-ratio: 1 / 1; }

.figure figcaption {
  padding: 0.7rem 1rem;
  border-top: 1px solid rgba(18, 51, 43, 0.08);
  background: rgba(247, 243, 234, 0.94);
  font-size: 0.8125rem;
  line-height: 1.6;
  color: var(--green-500);
}

.figure--placeholder .figure__media {
  background-color: var(--paper-200);
  background-image:
    repeating-radial-gradient(circle at 88% 12%,
      rgba(18, 51, 43, 0.10) 0 1px, transparent 1px 18px),
    linear-gradient(140deg, rgba(216, 181, 106, 0.28), rgba(169, 183, 189, 0.26));
}

/* 面包屑 */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4em;
  font-size: 0.8125rem;
  letter-spacing: 0.02em;
  color: var(--green-500);
}

.breadcrumb li { display: inline-flex; align-items: center; gap: 0.4em; }

.breadcrumb li + li::before {
  content: "›";
  font-family: var(--font-mono);
  color: var(--mist-400);
}

.breadcrumb a {
  color: var(--green-700);
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease-out), border-color 0.18s var(--ease-out);
}

.breadcrumb a:hover {
  color: var(--green-900);
  border-bottom-color: var(--gold-500);
}

.breadcrumb [aria-current="page"] {
  color: var(--green-900);
  font-weight: 600;
}

/* ---------- 7. 头部：品牌轨道 ---------- */
.site-header { position: relative; z-index: 80; }

.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 200;
  padding: 0.6rem 1.05rem;
  border-radius: var(--radius-pill);
  background: var(--gold-500);
  color: var(--ink-950);
  font-size: 0.875rem;
  font-weight: 700;
  transform: translateY(-180%);
  transition: transform 0.18s var(--ease-out);
}

.skip-link:focus,
.skip-link:focus-visible { transform: translateY(0); }

/* 移动端品牌条（桌面隐藏） */
.top-bar { display: none; }

.top-brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--paper-100);
}

.top-brand-text { font-weight: 800; letter-spacing: 0.05em; font-size: 1.05rem; }

.nav-toggle {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 0.5rem 0.95rem;
  border: 1px solid rgba(216, 181, 106, 0.55);
  border-radius: var(--radius-pill);
  color: var(--gold-200);
  font-size: 0.8125rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  transition: background-color 0.18s var(--ease-out),
    border-color 0.18s var(--ease-out), color 0.18s var(--ease-out);
}

.nav-toggle:hover {
  background: rgba(216, 181, 106, 0.16);
  border-color: var(--gold-500);
}

.nav-toggle-text { line-height: 1; }

.nav-toggle-bars {
  position: relative;
  display: inline-block;
  width: 18px;
  height: 12px;
}

.nav-toggle-bars::before,
.nav-toggle-bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.2s var(--ease-out), top 0.2s var(--ease-out),
    bottom 0.2s var(--ease-out);
}

.nav-toggle-bars::before { top: 0; }
.nav-toggle-bars::after { bottom: 0; }

.nav-toggle[aria-expanded="true"] .nav-toggle-bars::before {
  top: 5px;
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars::after {
  bottom: 5px;
  transform: rotate(-45deg);
}

/* 品牌轨道 */
.brand-rail {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  z-index: 80;
  display: flex;
  flex-direction: column;
  gap: 22px;
  width: var(--rail-w);
  padding: 30px 22px 24px;
  overflow-y: auto;
  background-color: var(--green-900);
  color: var(--paper-100);
  border-right: 1px solid rgba(216, 181, 106, 0.2);
}

.brand-rail::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.4;
  background-image:
    repeating-radial-gradient(circle at 118% 6%,
      rgba(169, 183, 189, 0.16) 0 1px, transparent 1px 26px);
}

.rail-head { position: relative; padding-right: 26px; }

.rail-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--paper-100);
}

.rail-brand-name {
  font-size: 1.05rem;
  font-weight: 800;
  letter-spacing: 0.05em;
}

.rail-mark,
.top-mark {
  position: relative;
  flex: none;
  width: 26px;
  height: 26px;
  border-radius: 9px;
  background: var(--gold-500);
}

.rail-mark::after,
.top-mark::after {
  content: "";
  position: absolute;
  inset: 6px;
  border: 2px solid var(--green-900);
  border-radius: 4px;
}

.rail-tagline {
  position: absolute;
  top: 4px;
  right: 0;
  writing-mode: vertical-rl;
  text-orientation: mixed;
  height: 110px;
  font-size: 0.72rem;
  letter-spacing: 0.3em;
  color: rgba(240, 217, 166, 0.75);
}

.rail-nav { flex: 1 1 auto; min-height: 0; }

.rail-nav-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.rail-link {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: center;
  gap: 10px;
  padding: 11px 12px 11px 14px;
  border-radius: 14px;
  font-size: 0.9375rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: rgba(247, 243, 234, 0.72);
  transition: background-color 0.18s var(--ease-out),
    color 0.18s var(--ease-out), box-shadow 0.18s var(--ease-out);
}

.rail-idx {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  color: var(--mist-400);
  font-variant-numeric: tabular-nums;
  transition: color 0.18s var(--ease-out);
}

.rail-label { line-height: 1.4; }

.rail-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: transparent;
  box-shadow: inset 0 0 0 1px rgba(169, 183, 189, 0.55);
  transition: transform 0.2s var(--ease-out),
    background-color 0.18s var(--ease-out),
    box-shadow 0.18s var(--ease-out);
}

.rail-link:hover,
.rail-link:focus-visible {
  background: rgba(47, 107, 86, 0.45);
  color: var(--paper-100);
}

.rail-link:hover .rail-dot,
.rail-link:focus-visible .rail-dot {
  background: var(--gold-200);
  box-shadow: none;
}

.rail-link:hover .rail-idx,
.rail-link:focus-visible .rail-idx { color: var(--gold-200); }

.rail-link[aria-current="page"] {
  background: var(--green-700);
  color: var(--paper-100);
  box-shadow: inset 3px 0 0 0 var(--gold-500);
}

.rail-link[aria-current="page"] .rail-idx { color: var(--gold-500); }

.rail-link[aria-current="page"] .rail-dot {
  background: var(--gold-500);
  box-shadow: 0 0 0 3px rgba(216, 181, 106, 0.22);
  transform: scale(1.15);
}

.rail-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.85rem 1rem;
  border-radius: var(--radius-pill);
  background: var(--gold-500);
  color: var(--ink-950);
  font-size: 0.9375rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  transition: background-color 0.18s var(--ease-out),
    transform 0.18s var(--ease-out);
}

.rail-cta:hover { background: var(--gold-200); }
.rail-cta:active { transform: translateY(1px); }

.rail-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px 8px;
  padding-top: 14px;
  border-top: 1px solid var(--hair-light);
  font-size: 0.75rem;
  color: rgba(169, 183, 189, 0.92);
  line-height: 1.6;
}

.rail-meta-key { letter-spacing: 0.16em; }

.rail-meta-val {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  color: var(--gold-200);
}

/* 滚动进度（仅桌面） */
.scroll-progress {
  display: none;
  position: fixed;
  top: 0;
  left: calc(var(--rail-w) - 3px);
  z-index: 70;
  width: 3px;
  height: 100vh;
  pointer-events: none;
  background: rgba(18, 51, 43, 0.08);
}

.scroll-progress-bar {
  display: block;
  width: 100%;
  height: 0;
  background: linear-gradient(180deg, var(--gold-500), var(--clay-500));
}

/* 抽屉遮罩 */
.rail-scrim {
  position: fixed;
  inset: 0;
  z-index: 85;
  display: none;
  background: rgba(14, 31, 26, 0.58);
}

.rail-scrim:not([hidden]) {
  display: block;
  animation: scrim-in 0.24s var(--ease-out) both;
}

@keyframes scrim-in {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* ---------- 8. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(48px, 8vw, 96px);
  background-color: var(--green-900);
  color: rgba(247, 243, 234, 0.76);
  border-top: 1px solid rgba(216, 181, 106, 0.35);
}

.site-footer::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 190px;
  pointer-events: none;
  background:
    radial-gradient(120% 100% at 12% 0%, rgba(216, 181, 106, 0.14), transparent 62%),
    repeating-radial-gradient(circle at 96% 0%,
      rgba(169, 183, 189, 0.12) 0 1px, transparent 1px 24px);
}

.footer-inner {
  position: relative;
  width: 100%;
  max-width: 1120px;
  margin-inline: auto;
  padding: clamp(36px, 5vw, 64px) clamp(20px, 4vw, 44px)
    clamp(24px, 3vw, 36px);
  display: grid;
  grid-template-columns: 1.05fr 1.5fr 0.95fr;
  gap: clamp(24px, 4vw, 44px);
}

.footer-wordmark {
  font-size: 1.6rem;
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: 0.04em;
  color: var(--paper-100);
}

.footer-statement {
  margin-top: 10px;
  max-width: 22ch;
  font-size: 0.95rem;
  line-height: 1.7;
  color: rgba(247, 243, 234, 0.74);
}

.footer-status {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  margin-top: 16px;
  font-size: 0.8125rem;
  line-height: 1.65;
  color: rgba(169, 183, 189, 0.95);
}

.footer-dot {
  flex: none;
  width: 8px;
  height: 8px;
  margin-top: 0.5em;
  border-radius: 50%;
  background: var(--clay-500);
  box-shadow: 0 0 0 3px rgba(197, 107, 74, 0.22);
}

.footer-nav {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(20px, 3vw, 36px);
}

.footer-col-title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  color: var(--gold-200);
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-col a {
  position: relative;
  display: inline-block;
  padding-bottom: 2px;
  font-size: 0.9375rem;
  color: rgba(247, 243, 234, 0.8);
  transition: color 0.18s var(--ease-out);
}

.footer-col a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  height: 1px;
  width: 0;
  background: var(--gold-500);
  transition: width 0.2s var(--ease-out);
}

.footer-col a:hover,
.footer-col a:focus-visible { color: var(--gold-200); }

.footer-col a:hover::after,
.footer-col a:focus-visible::after { width: 100%; }

.footer-contact-list {
  display: flex;
  flex-direction: column;
  gap: 11px;
  font-size: 0.9375rem;
  line-height: 1.6;
}

.footer-contact-list li {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.footer-k {
  font-size: 0.75rem;
  letter-spacing: 0.14em;
  color: rgba(169, 183, 189, 0.95);
}

.footer-contact-list .mono {
  font-size: 0.9375rem;
  color: var(--paper-100);
  word-break: break-all;
}

.footer-base {
  position: relative;
  width: 100%;
  max-width: 1120px;
  margin-inline: auto;
  padding: 18px clamp(20px, 4vw, 44px) 26px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 22px;
  border-top: 1px solid var(--hair-light);
  font-size: 0.8125rem;
  color: rgba(169, 183, 189, 0.9);
}

.footer-base p { line-height: 1.6; }
.footer-base .mono { color: rgba(169, 183, 189, 0.9); }

.to-top {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 0.5rem 0.95rem;
  border: 1px solid rgba(216, 181, 106, 0.45);
  border-radius: var(--radius-pill);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--gold-200);
  transition: background-color 0.18s var(--ease-out),
    border-color 0.18s var(--ease-out), color 0.18s var(--ease-out);
}

.to-top::before {
  content: "↑";
  font-family: var(--font-mono);
  line-height: 1;
}

.to-top:hover {
  background: var(--gold-500);
  border-color: var(--gold-500);
  color: var(--ink-950);
}

/* ---------- 9. 响应式 ---------- */
@media (min-width: 960px) {
  body { padding-left: var(--rail-w); }
  .scroll-progress { display: block; }
  #main-content { scroll-margin-top: 24px; }
}

@media (max-width: 1023px) {
  .footer-inner { grid-template-columns: 1fr 1fr; }
  .footer-intro { grid-column: 1 / -1; }
}

@media (max-width: 959px) {
  body { padding-top: 64px; }

  .top-bar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 95;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    height: 64px;
    padding-inline: clamp(14px, 4vw, 22px);
    background: var(--green-900);
    border-bottom: 1px solid rgba(216, 181, 106, 0.28);
  }

  .brand-rail {
    width: min(330px, 88vw);
    z-index: 90;
    padding-top: 22px;
    border-right: 0;
    transform: translateX(-104%);
    transition: transform 0.3s var(--ease-out),
      box-shadow 0.3s var(--ease-out);
  }

  .brand-rail[data-open] {
    transform: translateX(0);
    box-shadow: 0 0 0 1px rgba(216, 181, 106, 0.22),
      26px 0 60px rgba(14, 31, 26, 0.45);
  }

  .rail-head { padding-right: 0; }
  .rail-tagline { display: none; }

  body.is-nav-open { overflow: hidden; }

  .figure--wide .figure__media { aspect-ratio: 3 / 2; }
}

@media (max-width: 860px) {
  .grid--2,
  .grid--3,
  .split { grid-template-columns: minmax(0, 1fr); }
}

@media (max-width: 639px) {
  .footer-inner { grid-template-columns: minmax(0, 1fr); }
  .footer-nav { gap: 22px; }
  .footer-base { flex-direction: column; align-items: flex-start; }
  .figure--wide .figure__media { aspect-ratio: 4 / 3; }
  .figure { border-radius: var(--radius-lg); }
}

/* ---------- 10. 动效降级 ---------- */
@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;
    scroll-behavior: auto !important;
  }
}