/* =========================================================
   新葡萄8883指南 — /assets/site.css
   共享外壳 · 葡萄主题数字手册 · 堆叠画板体系
   ========================================================= */

/* ---------- 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, figure, blockquote, dl, dd, ul, ol {
  margin: 0;
}

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

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

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

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

:focus-visible {
  outline: 2px solid #6B2C91;
  outline-offset: 3px;
  border-radius: 3px;
}

[id] { scroll-margin-top: 96px; }

/* ---------- 2. 设计变量 ---------- */
:root {
  /* 品牌色 */
  --grape: #6B2C91;
  --grape-deep: #3E1656;
  --grape-ink: #2A0F3B;
  --green: #A8D5A2;
  --green-vein: #4F7A52;
  --amber: #D4A017;

  /* 中性色 */
  --warm: #FBF8F3;
  --lilac: #EDE7F2;
  --mist: #C9B8DA;
  --ink: #1E1724;
  --paper: #D8D2CC;

  /* 语义 */
  --text: var(--ink);
  --text-muted: #5C5167;
  --text-on-dark: rgba(251, 248, 243, 0.86);
  --text-on-dark-soft: rgba(251, 248, 243, 0.70);
  --line: var(--mist);
  --surface: #FFFFFF;
  --surface-alt: var(--lilac);

  /* 字体 */
  --font-display: "Noto Serif SC", "Source Han Serif SC", "Source Han Serif CN", "Songti SC", "STSong", "SimSun", serif;
  --font-body: "Noto Sans SC", "Source Han Sans SC", "Source Han Sans CN", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, sans-serif;
  --font-mono: "IBM Plex Mono", "JetBrains Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;

  /* 结构 */
  --maxw: 1280px;
  --gutter: clamp(20px, 4vw, 48px);
  --header-h: 78px;
  --radius: 18px;
  --radius-sm: 12px;
  --shadow-board: 0 1px 0 rgba(30, 23, 36, 0.03), 0 26px 50px -42px rgba(62, 22, 86, 0.65);
  --ease: cubic-bezier(0.22, 0.72, 0.28, 1);
}

/* ---------- 3. 基础排版 ---------- */
body {
  font-family: var(--font-body);
  font-size: 1rem;
  line-height: 1.75;
  color: var(--text);
  background-color: var(--warm);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  min-height: 100vh;
}

h1, h2, h3 {
  font-family: var(--font-display);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.01em;
}

h1 { font-size: clamp(2.4rem, 5vw, 4.8rem); line-height: 1.06; }
h2 { font-size: clamp(1.6rem, 2.6vw, 2.6rem); }
h3 { font-size: 1.25rem; line-height: 1.3; }

p { max-width: 46em; }

strong { font-weight: 700; }

::selection {
  background: var(--grape);
  color: #fff;
}

/* ---------- 4. 布局容器 ---------- */
.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding-left: var(--gutter);
  padding-right: var(--gutter);
}

.section {
  padding-top: clamp(48px, 7vw, 96px);
  padding-bottom: clamp(48px, 7vw, 96px);
}

.grid-12 {
  display: grid;
  grid-template-columns: repeat(12, minmax(0, 1fr));
  gap: clamp(16px, 2vw, 28px);
}

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

/* ---------- 5. 通用排版组件 ---------- */
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--grape);
}

.eyebrow::before {
  content: "";
  width: 22px;
  height: 1px;
  background: currentColor;
  flex: none;
}

.section-title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.6rem, 2.6vw, 2.6rem);
  line-height: 1.15;
  letter-spacing: -0.01em;
  margin-top: 12px;
}

.section-lede {
  margin-top: 14px;
  font-size: 1.0625rem;
  line-height: 1.8;
  color: var(--text-muted);
  max-width: 44em;
}

.meta-mono {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.06em;
  color: #6B5F77;
}

.link-vein {
  color: var(--green-vein);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
  text-decoration-color: rgba(79, 122, 82, 0.45);
  transition: color 0.16s var(--ease), text-decoration-color 0.16s var(--ease);
}

.link-vein:hover {
  color: var(--grape);
  text-decoration-color: currentColor;
}

/* ---------- 6. 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 20px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  line-height: 1.2;
  cursor: pointer;
  transition: transform 0.16s var(--ease), background-color 0.16s var(--ease),
              color 0.16s var(--ease), border-color 0.16s var(--ease),
              box-shadow 0.16s var(--ease);
}

.btn-primary {
  background: var(--grape);
  color: #FFFFFF;
  border-color: var(--grape);
  box-shadow: 0 12px 26px -16px rgba(62, 22, 86, 0.95);
}

.btn-primary:hover,
.btn-primary:focus-visible {
  background: var(--grape-deep);
  border-color: var(--grape-deep);
  transform: translateY(-1px);
}

.btn-secondary {
  background: transparent;
  color: var(--grape-deep);
  border-color: var(--mist);
}

.btn-secondary:hover,
.btn-secondary:focus-visible {
  background: var(--surface);
  border-color: var(--grape);
  color: var(--grape);
}

/* ---------- 7. 头部 ---------- */
.skip-link {
  position: absolute;
  left: 16px;
  top: -64px;
  z-index: 999;
  padding: 10px 18px;
  border-radius: 0 0 10px 10px;
  background: var(--grape-deep);
  color: #FFFFFF;
  font-size: 0.875rem;
  font-weight: 600;
  transition: top 0.18s var(--ease);
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 70;
  background-color: transparent;
  border-bottom: 1px solid transparent;
  transition: background-color 0.18s var(--ease),
              border-color 0.18s var(--ease),
              box-shadow 0.18s var(--ease);
}

.site-header.is-scrolled {
  background-color: rgba(251, 248, 243, 0.97);
  border-bottom-color: var(--mist);
  box-shadow: 0 1px 0 rgba(30, 23, 36, 0.04), 0 18px 34px -30px rgba(62, 22, 86, 0.7);
}

.header-inner {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--gutter);
  height: var(--header-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: clamp(16px, 2.4vw, 34px);
}

/* 品牌 */
.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
}

.brand-mark {
  width: 34px;
  height: 34px;
  flex: none;
  border-radius: 12px 12px 12px 5px;
  background:
    radial-gradient(circle at 66% 30%, var(--green) 0 20%, transparent 21%),
    radial-gradient(circle at 34% 62%, rgba(168, 213, 162, 0.55) 0 15%, transparent 16%),
    linear-gradient(148deg, var(--grape) 0%, var(--grape-deep) 100%);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.26),
              0 8px 16px -10px rgba(62, 22, 86, 0.85);
  transition: transform 0.2s var(--ease);
}

.brand:hover .brand-mark,
.brand:focus-visible .brand-mark {
  transform: rotate(-6deg) scale(1.04);
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.1;
}

.brand-name {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.0625rem;
  letter-spacing: 0.01em;
  color: var(--ink);
}

.brand-descriptor {
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 0.6563rem;
  letter-spacing: 0.16em;
  color: var(--grape);
}

/* 导航 */
.primary-nav {
  display: flex;
  align-items: center;
  gap: clamp(12px, 1.6vw, 24px);
  flex: 1 1 auto;
  justify-content: flex-end;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 2px;
}

.nav-link {
  position: relative;
  display: inline-block;
  padding: 8px 12px;
  border-radius: 999px;
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--ink);
  white-space: nowrap;
  transition: color 0.16s var(--ease), background-color 0.16s var(--ease);
}

.nav-link:hover {
  color: var(--grape);
  background-color: var(--lilac);
}

.nav-link[aria-current="page"] {
  color: var(--grape);
  font-weight: 700;
}

.nav-link[aria-current="page"]::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 2px;
  height: 2px;
  border-radius: 2px;
  background: var(--grape);
}

.nav-utility {
  display: flex;
  align-items: center;
  gap: 8px;
  padding-left: clamp(12px, 1.6vw, 22px);
  border-left: 1px solid var(--mist);
}

.util-link {
  display: inline-block;
  padding: 6px 11px;
  border-radius: 999px;
  border: 1px solid var(--mist);
  background: rgba(255, 255, 255, 0.55);
  font-family: var(--font-mono);
  font-size: 0.7188rem;
  letter-spacing: 0.06em;
  color: var(--grape-deep);
  white-space: nowrap;
  transition: border-color 0.16s var(--ease), color 0.16s var(--ease),
              background-color 0.16s var(--ease);
}

.util-link:hover,
.util-link:focus-visible {
  border-color: var(--grape);
  color: var(--grape);
  background: #FFFFFF;
}

.nav-cta { display: none; }

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
  flex: none;
}

.header-cta {
  white-space: nowrap;
}

/* 移动导航按钮 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  position: relative;
  z-index: 95;
  padding: 9px 14px;
  border-radius: 999px;
  border: 1px solid var(--mist);
  background: rgba(255, 255, 255, 0.6);
  font-size: 0.8125rem;
  font-weight: 600;
  color: var(--grape-deep);
  transition: color 0.18s var(--ease), border-color 0.18s var(--ease),
              background-color 0.18s var(--ease);
}

.nav-toggle-bars {
  display: inline-flex;
  flex-direction: column;
  gap: 4px;
  width: 16px;
}

.nav-toggle-bars span {
  display: block;
  height: 2px;
  border-radius: 2px;
  background: currentColor;
  transition: transform 0.22s var(--ease), opacity 0.22s var(--ease);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:first-child {
  transform: translateY(3px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-bars span:last-child {
  transform: translateY(-3px) rotate(-45deg);
}

.nav-toggle[aria-expanded="true"] {
  color: var(--warm);
  border-color: rgba(251, 248, 243, 0.45);
  background: rgba(251, 248, 243, 0.12);
}

/* 滚动进度条（JS 注入） */
.scroll-progress {
  position: absolute;
  left: 0;
  bottom: -1px;
  width: 100%;
  height: 2px;
  transform: scaleX(0);
  transform-origin: 0 50%;
  background: linear-gradient(90deg, var(--grape) 0%, var(--green) 58%, var(--amber) 100%);
  pointer-events: none;
}

/* 返回顶部（JS 注入） */
.back-top {
  position: fixed;
  right: clamp(16px, 3vw, 32px);
  bottom: clamp(16px, 3vw, 32px);
  z-index: 80;
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  border: 1px solid var(--mist);
  background: var(--warm);
  color: var(--grape-deep);
  font-size: 1rem;
  line-height: 1;
  box-shadow: 0 16px 30px -18px rgba(62, 22, 86, 0.85);
  opacity: 0;
  visibility: hidden;
  transform: translateY(10px);
  transition: opacity 0.2s var(--ease), transform 0.2s var(--ease),
              visibility 0.2s var(--ease), background-color 0.16s var(--ease);
}

.back-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.back-top:hover {
  background: var(--grape);
  color: #FFFFFF;
  border-color: var(--grape);
}

/* ---------- 8. 页脚 ---------- */
.site-footer {
  position: relative;
  margin-top: clamp(48px, 8vw, 110px);
  background: var(--grape-deep);
  color: var(--text-on-dark);
  border-top: 3px solid var(--green);
  overflow: hidden;
}

.site-footer::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(circle at 12% 0%, rgba(168, 213, 162, 0.16), transparent 46%),
    radial-gradient(circle at 88% 12%, rgba(212, 160, 23, 0.14), transparent 44%);
}

.footer-inner {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: clamp(40px, 6vw, 72px) var(--gutter) 28px;
}

.footer-top {
  display: grid;
  grid-template-columns: 1.5fr 0.72fr 0.72fr 1.15fr;
  gap: clamp(24px, 4vw, 48px);
}

.footer-brand-line {
  display: flex;
  align-items: center;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.3125rem;
  letter-spacing: 0.01em;
  color: #FFFFFF;
  max-width: none;
}

.footer-brand-line::before {
  content: "";
  width: 10px;
  height: 10px;
  flex: none;
  margin-right: 10px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 0 4px rgba(168, 213, 162, 0.18);
}

.footer-summary {
  margin-top: 14px;
  max-width: 30em;
  font-size: 0.9375rem;
  line-height: 1.8;
  color: var(--text-on-dark-soft);
}

.footer-meta-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 20px;
}

.footer-meta-item {
  padding: 4px 11px;
  border-radius: 999px;
  border: 1px solid rgba(201, 184, 218, 0.32);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  color: rgba(251, 248, 243, 0.74);
}

.footer-col-title {
  margin-bottom: 16px;
  font-family: var(--font-mono);
  font-size: 0.7188rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--green);
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-link {
  display: inline-block;
  font-size: 0.9375rem;
  color: var(--text-on-dark-soft);
  transition: color 0.16s var(--ease), transform 0.16s var(--ease);
}

.footer-link:hover,
.footer-link:focus-visible {
  color: #FFFFFF;
  transform: translateX(3px);
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 1px;
  text-decoration-color: var(--green);
}

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

.footer-contact-item {
  display: block;
  padding-left: 12px;
  border-left: 1px solid rgba(168, 213, 162, 0.4);
}

.footer-contact-label {
  display: block;
  margin-bottom: 3px;
  font-family: var(--font-mono);
  font-size: 0.6563rem;
  letter-spacing: 0.16em;
  color: var(--mist);
}

.footer-contact-value {
  display: block;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: rgba(251, 248, 243, 0.9);
  word-break: break-word;
}

.footer-contact-link {
  margin-top: 4px;
  font-size: 0.875rem;
  color: var(--green);
}

.footer-bottom {
  margin-top: clamp(32px, 5vw, 56px);
  padding-top: 22px;
  border-top: 1px solid rgba(201, 184, 218, 0.24);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 28px;
}

.legal-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 22px;
}

.legal-link {
  font-size: 0.8125rem;
  color: rgba(251, 248, 243, 0.7);
  transition: color 0.16s var(--ease);
}

.legal-link:hover,
.legal-link:focus-visible {
  color: var(--green);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.footer-icp,
.footer-note,
.footer-copy {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  color: rgba(201, 184, 218, 0.82);
  max-width: none;
}

.footer-note {
  color: rgba(251, 248, 243, 0.62);
}

/* ---------- 9. 面包屑 ---------- */
.breadcrumb {
  padding-top: 20px;
}

.crumb-list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  color: #6B5F77;
}

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

.crumb-item + .crumb-item::before {
  content: "/";
  margin-right: 8px;
  color: var(--mist);
}

.crumb-link {
  color: var(--green-vein);
  transition: color 0.16s var(--ease);
}

.crumb-link:hover,
.crumb-link:focus-visible {
  color: var(--grape);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.crumb-current {
  color: var(--ink);
  font-weight: 600;
}

/* ---------- 10. 画板卡片 ---------- */
.board {
  position: relative;
  padding: clamp(20px, 3vw, 32px);
  border: 1px solid var(--mist);
  border-radius: var(--radius);
  background: var(--surface);
  box-shadow: var(--shadow-board);
}

.board-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 14px;
  padding-bottom: 14px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--line);
}

.board-index {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  letter-spacing: 0.16em;
  color: var(--grape);
}

/* ---------- 11. 标签 ---------- */
.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid transparent;
  background: var(--lilac);
  color: var(--grape-deep);
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.08em;
  line-height: 1.6;
}

.tag-green {
  background: var(--green);
  color: #25401F;
}

.tag-amber {
  background: rgba(212, 160, 23, 0.18);
  border-color: rgba(212, 160, 23, 0.55);
  color: #6E5100;
}

/* ---------- 12. 图片容器基础规则 ---------- */
.media-frame {
  position: relative;
  overflow: hidden;
  isolation: isolate;
  border-radius: var(--radius-sm);
  background: linear-gradient(150deg, var(--lilac) 0%, var(--mist) 100%);
  aspect-ratio: 4 / 3;
  box-shadow: inset 0 0 0 1px rgba(201, 184, 218, 0.55);
}

.media-frame img,
.media-frame picture,
.media-frame picture > img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.media-frame::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(205deg, rgba(107, 44, 145, 0.26) 0%, transparent 52%, rgba(62, 22, 86, 0.34) 100%);
  mix-blend-mode: multiply;
}

.media-frame--wide { aspect-ratio: 16 / 9; }
.media-frame--tall { aspect-ratio: 3 / 4; }
.media-frame--sq { aspect-ratio: 1 / 1; }

/* ---------- 13. 滚动显现 ---------- */
.reveal-ready {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.62s var(--ease), transform 0.62s var(--ease);
  will-change: opacity, transform;
}

.reveal-ready.is-visible {
  opacity: 1;
  transform: none;
  will-change: auto;
}

/* ---------- 14. 平板 ---------- */
@media (max-width: 1180px) {
  .nav-utility { display: none; }
  .header-cta { padding: 10px 16px; font-size: 0.8125rem; }
}

@media (max-width: 1000px) {
  .footer-top {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }

  .footer-brand { grid-column: 1 / -1; }
}

/* ---------- 15. 移动导航 ---------- */
@media (max-width: 960px) {
  :root { --header-h: 64px; }

  .header-inner { gap: 12px; }

  .header-cta { display: none; }

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

  .primary-nav {
    position: fixed;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    z-index: 90;
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    justify-content: flex-start;
    gap: 0;
    padding: calc(var(--header-h) + 26px) clamp(20px, 6vw, 36px) 36px;
    background: var(--grape-deep);
    overflow-y: auto;
    transform: translateX(102%);
    visibility: hidden;
    transition: transform 0.34s var(--ease), visibility 0.34s var(--ease);
    box-shadow: -30px 0 70px -34px rgba(30, 23, 36, 0.7);
  }

  .primary-nav[data-open] {
    transform: translateX(0);
    visibility: visible;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
  }

  .nav-link {
    display: block;
    padding: 14px;
    border-radius: 12px;
    font-size: 1.0625rem;
    color: var(--text-on-dark);
  }

  .nav-link:hover {
    background: rgba(251, 248, 243, 0.08);
    color: #FFFFFF;
  }

  .nav-link[aria-current="page"] {
    background: rgba(168, 213, 162, 0.16);
    color: #FFFFFF;
  }

  .nav-link[aria-current="page"]::after {
    display: none;
  }

  .nav-utility {
    display: flex;
    flex-wrap: wrap;
    margin-top: 22px;
    padding: 22px 0 0;
    border-left: 0;
    border-top: 1px solid rgba(201, 184, 218, 0.3);
  }

  .util-link {
    border-color: rgba(168, 213, 162, 0.45);
    background: transparent;
    color: var(--green);
  }

  .util-link:hover,
  .util-link:focus-visible {
    background: rgba(168, 213, 162, 0.14);
    color: #FFFFFF;
    border-color: var(--green);
  }

  .nav-cta {
    display: inline-flex;
    margin-top: 26px;
    align-self: flex-start;
    background: var(--green);
    border-color: var(--green);
    color: #25401F;
    box-shadow: none;
  }

  .nav-cta:hover,
  .nav-cta:focus-visible {
    background: #FFFFFF;
    border-color: #FFFFFF;
    color: var(--grape-deep);
  }

  .brand-descriptor { display: none; }
}

/* ---------- 16. 手机 ---------- */
@media (max-width: 640px) {
  body { font-size: 0.9688rem; }

  .brand-mark { width: 30px; height: 30px; }

  .brand-name { font-size: 1rem; }

  .grid-12 { grid-template-columns: repeat(6, minmax(0, 1fr)); }

  .footer-top { grid-template-columns: 1fr; }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
    gap: 10px;
  }

  .back-top {
    width: 42px;
    height: 42px;
  }
}

/* ---------- 17. 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;
    scroll-behavior: auto !important;
  }

  .reveal-ready,
  .reveal-ready.is-visible {
    opacity: 1 !important;
    transform: none !important;
  }

  .brand:hover .brand-mark { transform: none; }

  .back-top { transform: none; }
}