/* ==========================================================================
   BBIN线上主站 · 共享样式表 /assets/site.css
   骨架：技术蓝图网格 + 纸本叠层 + 珠宝色分区
   ========================================================================== */

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 1.5rem;
}

body,
h1, h2, h3, h4, h5, h6,
p, figure, blockquote, dl, dd,
ul, ol { margin: 0; }

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

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

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

a { color: inherit; }

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

/* ---------- 2. 变量 ---------- */
:root {
  --ink-deep: #0B1C2C;
  --ink-2: #12303F;
  --line-blue: #27536B;
  --paper: #F4F1EA;
  --paper-2: #E4DED2;
  --gold: #C9A227;
  --celadon: #7FB3A3;
  --wine: #5B2A3A;
  --indigo: #2E2A55;
  --graphite: #2B2E33;
  --muted: #6E7681;

  --font-head: "Noto Sans SC", "Archivo Narrow", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-body: "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, "Noto Sans Mono CJK SC", monospace;

  --wrap: 1360px;
  --gutter: clamp(1.15rem, 4vw, 3rem);
  --hair: 1px solid rgba(39, 83, 107, 0.55);
  --hair-ink: 1px solid rgba(11, 28, 44, 0.14);
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

/* ---------- 3. 基础排版 ---------- */
html { background: var(--ink-deep); }

body {
  background: var(--paper);
  color: var(--graphite);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.9;
  letter-spacing: 0.012em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4 {
  font-family: var(--font-head);
  font-weight: 600;
  line-height: 1.16;
  letter-spacing: 0.03em;
}

strong { font-weight: 600; color: var(--ink-deep); }

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

:focus-visible {
  outline: 2px solid var(--gold);
  outline-offset: 3px;
}

#main-content { scroll-margin-top: 1.5rem; }

/* ---------- 4. 布局容器 ---------- */
.wrap {
  width: min(100% - (var(--gutter) * 2), var(--wrap));
  margin-inline: auto;
}

.section { padding: clamp(2.6rem, 6.5vw, 5rem) 0; }
.section--tight { padding: clamp(1.6rem, 4vw, 2.6rem) 0; }
.section--deep { background: var(--ink-deep); color: var(--paper); }
.section--night { background: var(--ink-2); color: var(--paper); }
.section--paper2 { background: var(--paper-2); }
.section--wine { background: var(--wine); color: var(--paper); }
.section--indigo { background: var(--indigo); color: var(--paper); }
.section--narrow > .wrap { width: min(100% - (var(--gutter) * 2), 900px); }
.section--hair { border-top: var(--hair-ink); }

/* 三栏不对称栅格 */
.rails {
  display: grid;
  grid-template-columns: 160px minmax(0, 1fr) 200px;
  gap: clamp(1.3rem, 3vw, 2.6rem);
  align-items: start;
}

.rail {
  position: sticky;
  top: 1.6rem;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.7;
  letter-spacing: 0.06em;
}

.rail__title {
  font-size: 11px;
  letter-spacing: 0.2em;
  color: var(--muted);
  padding-bottom: 0.55rem;
  margin-bottom: 0.85rem;
  border-bottom: var(--hair-ink);
}

.rail__list { display: grid; gap: 0.35rem; }

.rail__link {
  display: block;
  color: var(--muted);
  text-decoration: none;
  padding: 0.18rem 0 0.18rem 0.7rem;
  border-left: 1px solid rgba(11, 28, 44, 0.16);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.rail__link:hover { color: var(--ink-deep); border-color: var(--celadon); }
.rail__link.is-active { color: var(--ink-deep); border-color: var(--gold); }

.section--deep .rail__title,
.section--night .rail__title,
.section--wine .rail__title,
.section--indigo .rail__title {
  color: rgba(244, 241, 234, 0.5);
  border-color: rgba(39, 83, 107, 0.8);
}

.section--deep .rail__link,
.section--night .rail__link,
.section--wine .rail__link,
.section--indigo .rail__link {
  color: rgba(244, 241, 234, 0.62);
  border-color: rgba(39, 83, 107, 0.8);
}

.section--deep .rail__link:hover,
.section--night .rail__link:hover,
.section--deep .rail__link.is-active,
.section--night .rail__link.is-active {
  color: var(--gold);
  border-color: var(--gold);
}

.grid-2 { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: clamp(1.2rem, 3vw, 2.2rem); }
.grid-3 { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: clamp(1.2rem, 3vw, 2rem); }

/* ---------- 5. 跳转链接 ---------- */
.skip-link {
  position: absolute;
  left: 1rem;
  top: -6rem;
  z-index: 200;
  padding: 0.7rem 1.1rem;
  background: var(--gold);
  color: var(--ink-deep);
  font-size: 14px;
  font-weight: 500;
  letter-spacing: 0.08em;
  text-decoration: none;
  transition: top 0.2s var(--ease);
}

.skip-link:focus { top: 1rem; }

/* ---------- 6. 页头 / 刊头 ---------- */
.site-header {
  position: relative;
  background: var(--ink-deep);
  color: var(--paper);
  overflow: hidden;
  border-bottom: 1px solid var(--line-blue);
}

.site-header__grid {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(39, 83, 107, 0.55) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(39, 83, 107, 0.28) 1px, transparent 1px);
  background-size: 84px 84px;
  opacity: 0.45;
  -webkit-mask-image: linear-gradient(to bottom, #000 0%, transparent 96%);
  mask-image: linear-gradient(to bottom, #000 0%, transparent 96%);
}

.site-header__inner { position: relative; z-index: 1; }

.masthead {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1rem;
  padding: clamp(1.5rem, 3.6vw, 2.6rem) 0 clamp(1rem, 2.2vw, 1.5rem);
}

.masthead__side { display: flex; align-items: center; gap: 0.9rem; }
.masthead__side--left { justify-content: flex-start; }
.masthead__side--right { justify-content: flex-end; }
.masthead__center { text-align: center; }

.brand-mark {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: 0.4rem;
  text-decoration: none;
  color: var(--paper);
}

.brand-mark__name {
  font-family: var(--font-head);
  font-weight: 600;
  font-size: clamp(1.7rem, 4.2vw, 2.9rem);
  line-height: 1.1;
  letter-spacing: 0.1em;
  text-indent: 0.1em;
  transition: color 0.22s var(--ease);
}

.brand-mark:hover .brand-mark__name { color: var(--gold); }

.brand-mark__note {
  font-family: var(--font-mono);
  font-size: 11px;
  line-height: 1.4;
  letter-spacing: 0.24em;
  text-indent: 0.24em;
  color: var(--celadon);
}

.masthead__utility {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: rgba(244, 241, 234, 0.72);
  text-decoration: none;
  padding: 0.35rem 0.2rem;
  border-bottom: 1px solid rgba(39, 83, 107, 0.95);
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.masthead__utility:hover { color: var(--gold); border-color: var(--gold); }

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 0.55rem;
  padding: 0.55rem 0.75rem;
  border: 1px solid var(--line-blue);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  transition: border-color 0.2s var(--ease), color 0.2s var(--ease);
}

.nav-toggle:hover { border-color: var(--gold); color: var(--gold); }

.nav-toggle__bars { position: relative; display: block; width: 16px; height: 10px; }

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  width: 16px;
  height: 1px;
  background: currentColor;
  transition: transform 0.24s var(--ease);
}

.nav-toggle__bars::before { top: 2px; }
.nav-toggle__bars::after { bottom: 2px; }

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { transform: translateY(3px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { transform: translateY(-3px) rotate(-45deg); }

/* 主导航 */
.site-nav {
  position: relative;
  z-index: 1;
  background: var(--ink-2);
  border-top: 1px solid var(--line-blue);
}

.site-nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: stretch;
}

.site-nav__item { display: flex; }

.site-nav__link {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.95rem 1.35rem;
  font-size: 14px;
  letter-spacing: 0.12em;
  color: rgba(244, 241, 234, 0.76);
  text-decoration: none;
  border-left: 1px solid rgba(39, 83, 107, 0.5);
  transition: color 0.2s var(--ease), background-color 0.2s var(--ease);
}

.site-nav__item:last-child .site-nav__link { border-right: 1px solid rgba(39, 83, 107, 0.5); }

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 0;
  width: 0;
  height: 2px;
  background: var(--gold);
  transform: translateX(-50%);
  transition: width 0.26s var(--ease);
}

.site-nav__link:hover { color: var(--paper); background: rgba(39, 83, 107, 0.34); }
.site-nav__link:hover::after { width: 42%; }

.site-nav__link[aria-current="page"] { color: var(--gold); }
.site-nav__link[aria-current="page"]::after { width: 64%; }

/* ---------- 7. 页脚 ---------- */
.site-footer {
  position: relative;
  background: var(--ink-deep);
  color: var(--paper);
  border-top: 1px solid var(--line-blue);
  padding: clamp(2.4rem, 6vw, 4rem) 0 1.6rem;
  overflow: hidden;
}

.site-footer__rule {
  position: absolute;
  inset: 0 0 auto 0;
  height: 3px;
  background: linear-gradient(
    90deg,
    var(--gold) 0 16%,
    var(--celadon) 16% 32%,
    var(--wine) 32% 44%,
    var(--indigo) 44% 58%,
    rgba(39, 83, 107, 0.9) 58% 100%
  );
  opacity: 0.85;
}

.footer-head {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem 1.6rem;
  padding-bottom: 1.7rem;
  border-bottom: var(--hair);
}

.footer-head__brand-block { display: flex; flex-direction: column; gap: 0.3rem; }

.footer-head__brand {
  font-family: var(--font-head);
  font-weight: 600;
  font-size: clamp(1.3rem, 3vw, 1.9rem);
  line-height: 1.2;
  letter-spacing: 0.1em;
  color: var(--paper);
}

.footer-head__note {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--celadon);
}

.footer-grid {
  display: grid;
  grid-template-columns: 1fr 0.8fr 1.3fr;
  gap: clamp(1.6rem, 4vw, 3rem);
  padding: clamp(1.8rem, 4vw, 2.6rem) 0 clamp(1.6rem, 3.6vw, 2.4rem);
}

.footer-col__title {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--gold);
  padding-bottom: 0.6rem;
  margin-bottom: 0.9rem;
  border-bottom: 1px solid rgba(39, 83, 107, 0.7);
}

.footer-col__list { display: grid; gap: 0.45rem; }

.footer-col__list--plain {
  font-family: var(--font-mono);
  font-size: 13px;
  line-height: 1.85;
  letter-spacing: 0.02em;
  color: rgba(244, 241, 234, 0.76);
  word-break: break-word;
}

.footer-col__link {
  display: inline-block;
  font-size: 14px;
  letter-spacing: 0.05em;
  color: rgba(244, 241, 234, 0.76);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.footer-col__link:hover { color: var(--gold); border-color: var(--gold); }

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.8rem 1.4rem;
  padding-top: 1.4rem;
  border-top: var(--hair);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: rgba(244, 241, 234, 0.6);
}

.footer-bottom__legal,
.footer-bottom__meta { line-height: 1.7; }

.to-top {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.5rem 0.85rem;
  border: 1px solid rgba(39, 83, 107, 0.95);
  color: rgba(244, 241, 234, 0.72);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.to-top:hover { color: var(--gold); border-color: var(--gold); }

/* ---------- 8. 通用按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.55rem;
  padding: 0.75rem 1.3rem;
  font-family: var(--font-body);
  font-size: 13px;
  font-weight: 500;
  line-height: 1;
  letter-spacing: 0.14em;
  text-decoration: none;
  border: 1px solid currentColor;
  background: transparent;
  color: var(--paper);
  transition: background-color 0.2s var(--ease), color 0.2s var(--ease), border-color 0.2s var(--ease);
}

.btn:hover { background: var(--paper); color: var(--ink-deep); border-color: var(--paper); }
.btn--gold { color: var(--gold); }
.btn--gold:hover { background: var(--gold); color: var(--ink-deep); border-color: var(--gold); }
.btn--celadon { color: var(--celadon); }
.btn--celadon:hover { background: var(--celadon); color: var(--ink-deep); border-color: var(--celadon); }
.btn--ink { color: var(--ink-deep); border-color: rgba(11, 28, 44, 0.5); }
.btn--ink:hover { background: var(--ink-deep); color: var(--paper); border-color: var(--ink-deep); }
.btn--solid-gold { background: var(--gold); color: var(--ink-deep); border-color: var(--gold); }
.btn--solid-gold:hover { background: transparent; color: var(--gold); }

/* ---------- 9. 面包屑 / 页头区块 ---------- */
.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
}

.breadcrumb__item { display: inline-flex; align-items: center; gap: 0.5rem; }
.breadcrumb__item + .breadcrumb__item::before { content: "/"; color: rgba(110, 118, 129, 0.6); }
.breadcrumb a { text-decoration: none; border-bottom: 1px solid transparent; }
.breadcrumb a:hover { color: var(--gold); border-color: var(--gold); }
.breadcrumb [aria-current="page"] { color: var(--ink-deep); }

.section--deep .breadcrumb,
.section--night .breadcrumb { color: rgba(244, 241, 234, 0.6); }
.section--deep .breadcrumb [aria-current="page"],
.section--night .breadcrumb [aria-current="page"] { color: var(--paper); }

.page-head { padding: clamp(2rem, 5vw, 3.4rem) 0 clamp(1.2rem, 3vw, 2rem); }

.page-head__title {
  margin-top: 1rem;
  font-size: clamp(2rem, 5.4vw, 3.4rem);
  line-height: 1.14;
  color: var(--ink-deep);
}

.page-head__lede {
  margin-top: 1rem;
  max-width: 58ch;
  font-size: 17px;
  line-height: 1.9;
  color: var(--muted);
}

.section--deep .page-head__title,
.section--night .page-head__title { color: var(--paper); }
.section--deep .page-head__lede,
.section--night .page-head__lede { color: rgba(244, 241, 234, 0.68); }

/* ---------- 10. 小元件 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1;
  letter-spacing: 0.2em;
  color: var(--muted);
}

.eyebrow::before { content: ""; width: 22px; height: 1px; background: var(--gold); }
.section--deep .eyebrow,
.section--night .eyebrow { color: rgba(244, 241, 234, 0.62); }

.num-index {
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1;
  letter-spacing: 0.14em;
  color: var(--gold);
}

.section-title {
  margin-top: 0.9rem;
  font-size: clamp(1.55rem, 3.6vw, 2.35rem);
  line-height: 1.18;
  color: var(--ink-deep);
}

.section--deep .section-title,
.section--night .section-title,
.section--wine .section-title,
.section--indigo .section-title { color: var(--paper); }

.section-lede {
  margin-top: 0.9rem;
  max-width: 52ch;
  font-size: 17px;
  line-height: 1.9;
  color: var(--muted);
}

.section--deep .section-lede,
.section--night .section-lede,
.section--wine .section-lede,
.section--indigo .section-lede { color: rgba(244, 241, 234, 0.68); }

.tag {
  display: inline-block;
  padding: 0.38rem 0.6rem;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.4;
  letter-spacing: 0.1em;
  color: var(--ink-2);
  background: var(--paper-2);
  border: 1px solid rgba(11, 28, 44, 0.14);
}

.tag--gold { color: #6a5410; background: rgba(201, 162, 39, 0.16); border-color: rgba(201, 162, 39, 0.5); }
.tag--celadon { color: #2c5a4c; background: rgba(127, 179, 163, 0.18); border-color: rgba(127, 179, 163, 0.55); }
.tag--deep { color: var(--paper); background: rgba(39, 83, 107, 0.55); border-color: var(--line-blue); }

.paper {
  background: var(--paper);
  border: var(--hair-ink);
  box-shadow: 4px 4px 0 rgba(11, 28, 44, 0.06), 8px 8px 0 rgba(228, 222, 210, 0.9);
}

.paper--tint { background: var(--paper-2); }
.paper--pad { padding: clamp(1.1rem, 2.6vw, 1.8rem); }

.rule-dotted {
  height: 1px;
  border: 0;
  background-image: linear-gradient(to right, rgba(11, 28, 44, 0.28) 1px, transparent 1px);
  background-size: 8px 1px;
  background-repeat: repeat-x;
  margin: 1.6rem 0;
}

.section--deep .rule-dotted,
.section--night .rule-dotted {
  background-image: linear-gradient(to right, rgba(39, 83, 107, 0.9) 1px, transparent 1px);
}

/* ---------- 11. 图片容器基础规则 ---------- */
.figure-frame {
  position: relative;
  border: 1px solid rgba(39, 83, 107, 0.6);
  background: var(--ink-2);
  overflow: hidden;
}

.figure-frame__media {
  display: block;
  width: 100%;
  height: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.figure-frame--wide .figure-frame__media { aspect-ratio: 21 / 9; }
.figure-frame--square .figure-frame__media { aspect-ratio: 1 / 1; }
.figure-frame--portrait .figure-frame__media { aspect-ratio: 3 / 4; }

.figure-frame--blank { aspect-ratio: 16 / 10; }

.figure-frame--blank::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(39, 83, 107, 0.6) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(39, 83, 107, 0.35) 1px, transparent 1px);
  background-size: 40px 40px;
}

.figure-frame__caption {
  padding: 0.6rem 0.85rem;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: 0.06em;
  color: var(--muted);
  background: var(--paper);
  border-top: 1px solid rgba(39, 83, 107, 0.4);
}

/* ---------- 12. 正文区 ---------- */
.prose { font-size: 17px; line-height: 1.9; color: var(--graphite); }
.prose > * + * { margin-top: 1.15em; }
.prose h2 { font-size: clamp(1.4rem, 3vw, 1.9rem); line-height: 1.25; margin-top: 2.2rem; }
.prose h3 { font-size: 1.18rem; line-height: 1.35; margin-top: 1.6rem; }
.prose ul, .prose ol { padding-left: 1.35rem; display: grid; gap: 0.45rem; }
.prose ul { list-style: square; }
.prose ol { list-style: decimal; }
.prose li::marker { color: var(--gold); }
.prose a { color: var(--ink-deep); text-decoration: none; border-bottom: 1px solid var(--gold); }
.prose a:hover { color: var(--gold); }
.prose blockquote { border-left: 2px solid var(--gold); padding: 0.3rem 0 0.3rem 1.15rem; color: var(--muted); }
.prose code { font-family: var(--font-mono); font-size: 0.9em; background: var(--paper-2); padding: 0.1em 0.4em; }
.prose hr { border: 0; border-top: var(--hair-ink); margin: 2rem 0; }

.section--deep .prose,
.section--night .prose { color: rgba(244, 241, 234, 0.86); }
.section--deep .prose a,
.section--night .prose a { color: var(--paper); }

/* ---------- 13. 显现动效 ---------- */
html.has-js [data-reveal] {
  opacity: 0;
  transform: translateY(10px);
  transition: opacity 0.26s var(--ease), transform 0.26s var(--ease);
}

html.has-js [data-reveal].is-visible { opacity: 1; transform: none; }

/* ---------- 14. 响应式 ---------- */
@media (max-width: 1180px) {
  .rails { grid-template-columns: 150px minmax(0, 1fr); }
  .rail--right { display: none; }
}

@media (max-width: 1024px) {
  .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .footer-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  .rails { grid-template-columns: minmax(0, 1fr); }
  .rail { position: static; }
  .rail--left { display: none; }

  .masthead { grid-template-columns: 1fr auto; align-items: center; }
  .masthead__side--left { display: none; }
  .masthead__side--right .masthead__utility { display: none; }
  .masthead__center { justify-self: start; text-align: left; }
  .brand-mark { align-items: flex-start; }

  .nav-toggle { display: inline-flex; }

  .site-nav {
    overflow: hidden;
    max-height: 0;
    transition: max-height 0.3s var(--ease);
  }

  .site-nav[data-open="true"] { max-height: 30rem; }

  .site-nav__list { flex-direction: column; align-items: stretch; }

  .site-nav__link {
    justify-content: space-between;
    padding: 0.9rem 1.15rem;
    border-left: 0;
    border-top: 1px solid rgba(39, 83, 107, 0.5);
  }

  .site-nav__item:last-child .site-nav__link { border-right: 0; }
  .site-nav__link::after { display: none; }
  .site-nav__link:hover { background: rgba(39, 83, 107, 0.4); }
  .site-nav__link[aria-current="page"] { background: rgba(201, 162, 39, 0.1); }

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

@media (max-width: 640px) {
  body { font-size: 15.5px; }
  .prose { font-size: 16px; }
  .footer-grid { grid-template-columns: minmax(0, 1fr); }
  .footer-bottom { flex-direction: column; align-items: flex-start; }
  .brand-mark__name { letter-spacing: 0.06em; text-indent: 0.06em; }
  .figure-frame--wide .figure-frame__media { aspect-ratio: 16 / 10; }
}

/* ---------- 15. 动效偏好 ---------- */
@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;
  }

  html.has-js [data-reveal] { opacity: 1; transform: none; }
  .site-nav { transition: none; }
}