/* ==========================================================================
   久赢平台 · 中国官方主站  共享样式表  /assets/site.css
   目录型内容地图 · 居中刊头 · 控制台质感 · 半透明玻璃层与实色内容层并置
   ========================================================================== */

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

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

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

ul, ol { list-style: none; }

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

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

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

main { display: block; }

#main-content { outline: none; }

/* ---------- 2. 设计变量 ---------- */
:root {
  /* 品牌色 */
  --ink: #0B1F33;
  --ink-2: #17324D;
  --ink-3: #1F3E5C;
  --gold: #C8A24A;
  --gold-soft: #E4C97E;
  --celadon: #5F9E8F;
  --electric: #2BD9C8;
  --warm: #F7F3EA;
  --neutral: #E7E3DA;
  --graphite: #2E3A45;
  --violet: #6C5CE7;

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

  /* 布局 */
  --shell: 1180px;
  --gutter: clamp(18px, 4vw, 44px);
  --r-sm: 6px;
  --r-md: 12px;
  --r-lg: 20px;

  /* 线与层 */
  --line: rgba(11, 31, 51, .14);
  --line-strong: rgba(11, 31, 51, .28);
  --glass: rgba(255, 255, 255, .62);
  --glass-line: rgba(11, 31, 51, .10);

  /* 投影 */
  --shadow-1: 0 1px 0 rgba(11, 31, 51, .05), 0 10px 30px -22px rgba(11, 31, 51, .45);
  --shadow-2: 0 18px 44px -28px rgba(11, 31, 51, .55);

  --ease: cubic-bezier(.22, .61, .36, 1);
}

/* ---------- 3. 基础中文排版 ---------- */
body {
  background-color: var(--warm);
  background-image:
    linear-gradient(rgba(11, 31, 51, .040) 1px, transparent 1px),
    linear-gradient(90deg, rgba(11, 31, 51, .040) 1px, transparent 1px);
  background-size: 96px 96px, 96px 96px;
  background-attachment: fixed;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.75;
  letter-spacing: .01em;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-head);
  font-weight: 800;
  line-height: 1.16;
  letter-spacing: -.012em;
  color: var(--ink);
}

h1 { font-size: clamp(2.1rem, 5.6vw, 4.5rem); }
h2 { font-size: clamp(1.6rem, 3.2vw, 2.75rem); }
h3 { font-size: clamp(1.25rem, 2vw, 1.75rem); }
h4 { font-size: 1.125rem; }

p { text-wrap: pretty; }

strong { font-weight: 700; }

code, kbd, samp { font-family: var(--font-mono); font-size: .92em; }

/* 焦点反馈 */
:focus-visible {
  outline: 2px solid var(--electric);
  outline-offset: 3px;
  border-radius: 2px;
}

/* ---------- 4. 通用容器与章节 ---------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section { padding: clamp(44px, 7vw, 96px) 0; }

.section__head {
  display: grid;
  grid-template-columns: minmax(0, 4fr) minmax(0, 8fr);
  gap: clamp(18px, 3vw, 40px);
  align-items: start;
  margin-bottom: clamp(24px, 3.4vw, 44px);
}

.section-index {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(34px, 5vw, 56px);
  font-weight: 700;
  line-height: .9;
  letter-spacing: .02em;
  color: rgba(200, 162, 74, .48);
}

@supports (-webkit-text-stroke: 1px currentColor) {
  .section-index {
    color: transparent;
    -webkit-text-stroke: 1px var(--gold);
  }
}

.page-head {
  padding: clamp(32px, 6vw, 72px) 0 clamp(22px, 3.4vw, 38px);
  border-bottom: 1px solid var(--line);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: .22em;
  text-transform: uppercase;
  color: var(--celadon);
}

.eyebrow::before {
  content: "";
  width: 26px;
  height: 1px;
  background: currentColor;
  flex: none;
}

.lede {
  max-width: 64ch;
  font-size: clamp(17px, 1.55vw, 19px);
  line-height: 1.85;
  color: var(--graphite);
}

/* ---------- 5. 栅格 ---------- */
.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)); }
.grid--4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }
.grid--5-7 { grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); }
.grid--7-5 { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); }
.grid--4-8 { grid-template-columns: minmax(0, 4fr) minmax(0, 8fr); }

/* ---------- 6. 卡片材质 ---------- */
.card {
  position: relative;
  padding: clamp(20px, 2.4vw, 30px);
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: #FFFFFF;
  box-shadow: var(--shadow-1);
  transition: transform .28s var(--ease), box-shadow .28s var(--ease), background-color .28s var(--ease);
}

.card--solid { background: #FFFFFF; }

.card--ink {
  background: var(--ink);
  border-color: transparent;
  color: rgba(247, 243, 234, .86);
}

.card--ink .card__title,
.card--ink .card__index { color: var(--gold-soft); }

.card--glass {
  background: var(--glass);
  -webkit-backdrop-filter: blur(14px);
  backdrop-filter: blur(14px);
  border-color: var(--glass-line);
  box-shadow: var(--shadow-2);
}

.card--lift:hover,
.card--lift:focus-within {
  transform: translateY(-3px);
  box-shadow: var(--shadow-2);
}

.card--glass:hover {
  background: rgba(255, 255, 255, .78);
}

.card__index {
  display: inline-block;
  margin-bottom: 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .18em;
  color: var(--gold);
}

.card__title {
  margin-bottom: 8px;
  font-family: var(--font-head);
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.3;
}

.card__text {
  font-size: 15.5px;
  line-height: 1.75;
  color: var(--graphite);
}

/* ---------- 7. 标签 ---------- */
.tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid currentColor;
  border-radius: 999px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .12em;
  line-height: 1.6;
  white-space: nowrap;
}

.tag--gold { color: var(--gold); }
.tag--celadon { color: var(--celadon); }
.tag--violet { color: var(--violet); }

/* ---------- 8. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 13px 24px;
  border: 1px solid transparent;
  border-radius: 999px;
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: .02em;
  line-height: 1.2;
  transition: transform .24s var(--ease), background-color .24s var(--ease),
              color .24s var(--ease), border-color .24s var(--ease);
}

.btn--primary { background: var(--ink); color: var(--warm); border-color: var(--ink); }
.btn--primary:hover { background: var(--ink-2); transform: translateY(-2px); }

.btn--gold { background: var(--gold); color: var(--ink); border-color: var(--gold); }
.btn--gold:hover { background: var(--gold-soft); transform: translateY(-2px); }

.btn--ghost { background: transparent; color: var(--ink); border-color: var(--line-strong); }
.btn--ghost:hover { border-color: var(--gold); background: rgba(200, 162, 74, .10); transform: translateY(-2px); }

.btn__arrow { font-family: var(--font-mono); font-size: 13px; line-height: 1; }

/* ---------- 9. 面包屑 ---------- */
.breadcrumb {
  padding-top: 20px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--graphite);
}

.breadcrumb__list { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }

.breadcrumb__item { display: inline-flex; align-items: center; }

.breadcrumb__item:not(:last-child)::after {
  content: "/";
  margin-left: 8px;
  color: var(--gold);
}

.breadcrumb__link { color: var(--graphite); transition: color .2s var(--ease); }
.breadcrumb__link:hover { color: var(--ink); box-shadow: inset 0 -1px 0 var(--gold); }

.breadcrumb__item[aria-current="page"] { color: var(--ink); }

/* ---------- 10. 图片容器基础规则 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--r-md);
  background: linear-gradient(145deg, #0B1F33 0%, #17324D 58%, #1F3E5C 100%);
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(247, 243, 234, .07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(247, 243, 234, .07) 1px, transparent 1px);
  background-size: 40px 40px, 40px 40px;
}

.media-frame__image {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.media-frame__caption {
  position: absolute;
  left: 14px;
  bottom: 12px;
  z-index: 2;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .14em;
  color: rgba(247, 243, 234, .88);
}

.media-frame--16x9 { aspect-ratio: 16 / 9; }
.media-frame--4x3 { aspect-ratio: 4 / 3; }
.media-frame--1x1 { aspect-ratio: 1 / 1; }
.media-frame--3x4 { aspect-ratio: 3 / 4; }

/* ---------- 11. 可复制文本 ---------- */
.copyable {
  font-family: var(--font-mono);
  border-bottom: 1px dashed var(--line-strong);
  padding-bottom: 1px;
  transition: color .2s var(--ease), border-color .2s var(--ease);
}

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

/* ---------- 12. 跳过链接 ---------- */
.skip-link {
  position: absolute;
  top: -70px;
  left: 12px;
  z-index: 200;
  padding: 10px 18px;
  border-radius: 0 0 var(--r-sm) var(--r-sm);
  background: var(--ink);
  color: var(--warm);
  font-family: var(--font-head);
  font-size: 14px;
  transition: top .22s var(--ease);
}

.skip-link:focus { top: 0; }

/* ---------- 13. 滚动进度条 ---------- */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 160;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--gold), var(--celadon) 55%, var(--electric));
  pointer-events: none;
}

/* ---------- 14. 页头 ---------- */
.site-header {
  position: relative;
  z-index: 60;
  background: var(--warm);
  border-bottom: 1px solid var(--line-strong);
}

/* 14.1 状态条 */
.header-utility {
  background: var(--ink);
  color: rgba(247, 243, 234, .70);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
}

.header-utility__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 18px;
  min-height: 42px;
  padding-block: 6px;
}

.header-utility__status {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  letter-spacing: .06em;
}

.status-dot {
  width: 7px;
  height: 7px;
  flex: none;
  border-radius: 50%;
  background: var(--electric);
  box-shadow: 0 0 0 3px rgba(43, 217, 200, .18);
}

.header-utility__paths { display: flex; flex-wrap: wrap; gap: 8px; }

.path-chip {
  display: inline-flex;
  align-items: center;
  padding: 3px 11px;
  border: 1px solid rgba(200, 162, 74, .38);
  border-radius: 999px;
  color: rgba(247, 243, 234, .82);
  letter-spacing: .06em;
  transition: color .22s var(--ease), border-color .22s var(--ease), background-color .22s var(--ease);
}

.path-chip:hover {
  color: #FFFFFF;
  border-color: var(--gold-soft);
  background: rgba(200, 162, 74, .16);
}

/* 14.2 居中刊头 */
.masthead {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: clamp(20px, 3vw, 30px) var(--gutter) clamp(16px, 2.4vw, 22px);
  text-align: center;
  background: linear-gradient(180deg, rgba(255, 255, 255, .74), rgba(247, 243, 234, .52));
  -webkit-backdrop-filter: blur(10px);
  backdrop-filter: blur(10px);
}

.masthead__brand {
  display: inline-flex;
  align-items: center;
  gap: 16px;
  max-width: 100%;
}

.masthead__mark {
  position: relative;
  display: grid;
  place-items: center;
  width: 54px;
  height: 54px;
  flex: none;
  border: 1px solid var(--gold);
  border-radius: var(--r-sm);
  background: linear-gradient(160deg, rgba(200, 162, 74, .18), rgba(200, 162, 74, 0));
  color: var(--gold);
  font-family: var(--font-head);
  font-size: 17px;
  font-weight: 800;
  letter-spacing: .04em;
  line-height: 1;
}

.masthead__mark::after {
  content: "";
  position: absolute;
  inset: 4px;
  border: 1px solid rgba(200, 162, 74, .34);
  border-radius: 3px;
  pointer-events: none;
}

.masthead__text {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  text-align: left;
  gap: 3px;
  min-width: 0;
}

.masthead__name {
  font-family: var(--font-head);
  font-size: clamp(19px, 2.2vw, 26px);
  font-weight: 800;
  letter-spacing: .015em;
  color: var(--ink);
}

.masthead__tagline {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--graphite);
  opacity: .78;
}

/* 14.3 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 10px 16px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: rgba(255, 255, 255, .58);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .16em;
  transition: border-color .22s var(--ease), background-color .22s var(--ease);
}

.nav-toggle:hover { border-color: var(--gold); background: rgba(200, 162, 74, .12); }

.nav-toggle__bars {
  position: relative;
  display: block;
  width: 16px;
  height: 10px;
  flex: none;
}

.nav-toggle__bars::before,
.nav-toggle__bars::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  height: 1.5px;
  background: var(--ink);
  transition: transform .26s var(--ease), top .26s var(--ease), bottom .26s var(--ease);
}

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

.nav-toggle[aria-expanded="true"] .nav-toggle__bars::before { top: 4px; transform: rotate(45deg); }
.nav-toggle[aria-expanded="true"] .nav-toggle__bars::after { bottom: 4.5px; transform: rotate(-45deg); }
.nav-toggle[aria-expanded="true"] { border-color: var(--gold); background: rgba(200, 162, 74, .16); }

/* 14.4 栏目导航 */
.site-nav {
  position: relative;
  display: block;
  background: rgba(255, 255, 255, .56);
  -webkit-backdrop-filter: blur(12px);
  backdrop-filter: blur(12px);
  border-top: 1px solid var(--glass-line);
  box-shadow: inset 0 2px 0 -1px rgba(200, 162, 74, .55);
}

.site-nav__list {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: clamp(4px, 1.6vw, 26px);
  counter-reset: nav;
}

.site-nav__item { counter-increment: nav; }

.site-nav__link {
  position: relative;
  display: inline-block;
  padding: 15px 6px;
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: .06em;
  color: var(--ink-2);
  transition: color .22s var(--ease);
}

.site-nav__link::before {
  content: counter(nav, decimal-leading-zero);
  margin-right: 8px;
  font-family: var(--font-mono);
  font-size: 10px;
  font-weight: 500;
  letter-spacing: .1em;
  color: var(--gold);
  vertical-align: 2px;
}

.site-nav__link::after {
  content: "";
  position: absolute;
  left: 6px;
  right: 6px;
  bottom: 9px;
  height: 2px;
  background: var(--gold);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform .28s var(--ease), background-color .22s var(--ease);
}

.site-nav__link:hover { color: var(--ink); }
.site-nav__link:hover::after { transform: scaleX(1); }

.site-nav__link[aria-current="page"] { color: var(--ink); }
.site-nav__link[aria-current="page"]::after {
  transform: scaleX(1);
  background: var(--electric);
}

/* ---------- 15. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(56px, 8vw, 104px);
  background: var(--ink);
  color: rgba(247, 243, 234, .78);
  font-family: var(--font-body);
  font-size: 15px;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--gold) 0%, var(--gold-soft) 28%, var(--celadon) 66%, var(--electric) 100%);
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
  gap: clamp(28px, 5vw, 64px);
  padding: clamp(42px, 6vw, 76px) 0 clamp(30px, 4vw, 48px);
}

.footer-brand { display: flex; flex-direction: column; gap: 14px; }

.footer-brand__link {
  display: inline-flex;
  align-items: center;
  gap: 14px;
  max-width: 100%;
}

.footer-brand__mark {
  display: grid;
  place-items: center;
  width: 46px;
  height: 46px;
  flex: none;
  border: 1px solid var(--gold);
  border-radius: var(--r-sm);
  background: linear-gradient(160deg, rgba(200, 162, 74, .22), rgba(200, 162, 74, 0));
  color: var(--gold-soft);
  font-family: var(--font-head);
  font-size: 15px;
  font-weight: 800;
  letter-spacing: .04em;
  line-height: 1;
}

.footer-brand__name {
  font-family: var(--font-head);
  font-size: 18px;
  font-weight: 800;
  letter-spacing: .015em;
  color: var(--warm);
}

.footer-brand__note {
  max-width: 34ch;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(247, 243, 234, .62);
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(18px, 3vw, 40px);
}

.footer-col__title {
  margin-bottom: 14px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .26em;
  text-transform: uppercase;
  color: var(--gold-soft);
}

.footer-col__list { display: flex; flex-direction: column; gap: 2px; }

.footer-col__link {
  display: inline-block;
  padding: 5px 0;
  font-size: 15px;
  color: rgba(247, 243, 234, .80);
  box-shadow: inset 0 -1px 0 rgba(247, 243, 234, 0);
  transition: color .22s var(--ease), box-shadow .22s var(--ease), transform .22s var(--ease);
}

.footer-col__link:hover {
  color: var(--gold-soft);
  box-shadow: inset 0 -1px 0 var(--gold-soft);
  transform: translateX(2px);
}

.footer-contact {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: clamp(16px, 2.4vw, 30px);
  padding: clamp(22px, 3vw, 34px) 0;
  border-top: 1px solid rgba(247, 243, 234, .14);
}

.footer-contact__item { display: flex; flex-direction: column; gap: 6px; }

.footer-contact__label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: .2em;
  color: var(--celadon);
}

.footer-contact__value {
  font-size: 15px;
  line-height: 1.6;
  color: rgba(247, 243, 234, .88);
  word-break: break-word;
}

.footer-contact__note {
  padding-bottom: clamp(20px, 3vw, 30px);
  font-size: 13.5px;
  line-height: 1.75;
  color: rgba(247, 243, 234, .52);
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 24px;
  padding: 18px 0 26px;
  border-top: 1px solid rgba(247, 243, 234, .14);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: rgba(247, 243, 234, .58);
}

.footer-meta__icp { color: rgba(247, 243, 234, .68); }
.footer-meta__copy { color: rgba(247, 243, 234, .58); }

/* 回到顶部 */
.to-top {
  position: fixed;
  right: clamp(16px, 3vw, 34px);
  bottom: clamp(16px, 3vw, 34px);
  z-index: 150;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border: 1px solid rgba(200, 162, 74, .5);
  border-radius: 999px;
  background: rgba(11, 31, 51, .94);
  color: var(--warm);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .12em;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity .26s var(--ease), transform .26s var(--ease),
              visibility .26s var(--ease), border-color .22s var(--ease), background-color .22s var(--ease);
}

.to-top.is-visible { opacity: 1; visibility: visible; transform: none; }
.to-top:hover { border-color: var(--gold-soft); background: var(--ink-2); }

/* 复制状态提示 */
.copy-status {
  position: fixed;
  left: 50%;
  bottom: clamp(18px, 3vw, 34px);
  z-index: 155;
  padding: 9px 18px;
  border-radius: 999px;
  background: var(--ink);
  color: var(--warm);
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .1em;
  opacity: 0;
  visibility: hidden;
  transform: translate(-50%, 10px);
  transition: opacity .26s var(--ease), transform .26s var(--ease), visibility .26s var(--ease);
}

.copy-status.is-visible { opacity: 1; visibility: visible; transform: translate(-50%, 0); }

/* ---------- 16. 显现动效 ---------- */
.js [data-reveal] {
  opacity: 0;
  transform: translateY(12px);
  transition: opacity .5s var(--ease), transform .5s var(--ease);
}

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

/* ---------- 17. 响应式 ---------- */
@media (max-width: 1024px) {
  .grid--4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (max-width: 900px) {
  .masthead { padding-block: 20px 18px; }

  .nav-toggle {
    display: inline-flex;
    width: 100%;
    margin-top: 16px;
  }

  .site-nav { display: none; }

  .site-nav[data-open="true"] { display: block; }

  .site-nav__inner { padding-block: 6px 12px; }

  .site-nav__list {
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

  .site-nav__link {
    display: block;
    padding: 14px 4px;
    font-size: 16px;
    border-bottom: 1px solid var(--line);
  }

  .site-nav__link::after { display: none; }

  .site-nav__item:last-child .site-nav__link { border-bottom: 0; }

  .grid--3,
  .grid--4,
  .grid--5-7,
  .grid--7-5,
  .grid--4-8 { grid-template-columns: minmax(0, 1fr); }

  .section__head { grid-template-columns: minmax(0, 1fr); gap: 12px; }

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

@media (max-width: 640px) {
  body { font-size: 16px; }

  .header-utility__inner { justify-content: flex-start; }

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

  .masthead__brand { gap: 12px; }
  .masthead__mark { width: 46px; height: 46px; font-size: 15px; }
  .masthead__name { font-size: 17px; }
  .masthead__tagline { font-size: 10.5px; letter-spacing: .1em; }

  .footer-links { grid-template-columns: minmax(0, 1fr); gap: 22px; }
  .footer-contact { grid-template-columns: minmax(0, 1fr); }
  .footer-meta { flex-direction: column; align-items: flex-start; }

  .to-top { right: 14px; bottom: 14px; padding: 9px 14px; }
}

/* ---------- 18. 降低动态效果 ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }

  *,
  *::before,
  *::after {
    animation-duration: .001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .001ms !important;
  }

  .js [data-reveal] { opacity: 1; transform: none; }
}