/* ===== 01. 设计令牌 ===== */
:root {
  --paper: #FFF7EC;
  --paper-2: #F3E7D3;
  --ink: #2B2118;
  --charcoal: #1A1A2E;
  --orange: #FF6B35;
  --blue: #1E90FF;
  --lemon: #FFD93D;
  --green: #4CAF50;
  --mist: #5B6B7F;
  --brick: #C43E1C;
  --paper-line: rgba(43, 33, 24, 0.18);
  --paper-line-soft: rgba(43, 33, 24, 0.1);
  --font-display: "Songti SC", "Source Han Serif SC", "Noto Serif SC", "SimSun", Georgia, "Times New Roman", serif;
  --font-body: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "SFMono-Regular", Menlo, Consolas, "Roboto Mono", "Courier New", monospace;
  --wrap: 1240px;
  --gutter: clamp(18px, 4vw, 56px);
  --header-h: 76px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --shadow-card: 7px 7px 0 rgba(43, 33, 24, 0.16);
  --shadow-hard: 4px 4px 0 rgba(43, 33, 24, 0.9);
}

@media (max-width: 720px) {
  :root {
    --header-h: 62px;
  }
}

/* ===== 02. 基础重置与中文排版 ===== */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 20px);
}

body {
  margin: 0;
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.75;
  color: var(--ink);
  background-color: var(--paper);
  background-image: radial-gradient(rgba(43, 33, 24, 0.055) 1px, transparent 1px);
  background-size: 20px 20px;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

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

img {
  height: auto;
}

h1,
h2,
h3,
h4 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: -0.01em;
}

p {
  margin: 0;
}

a {
  color: var(--ink);
  text-underline-offset: 3px;
}

button {
  font: inherit;
  color: inherit;
}

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

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

main {
  padding-top: var(--header-h);
}

#main-content:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: -2px;
}

/* ===== 03. 文字工具 ===== */
.display-title {
  font-size: clamp(40px, 6.2vw, 72px);
  line-height: 1.06;
  letter-spacing: -0.02em;
}

.display-title em {
  font-family: var(--font-body);
  font-style: italic;
  font-weight: 800;
  letter-spacing: 0.01em;
}

.lede {
  font-family: var(--font-body);
  font-size: clamp(18px, 2.2vw, 23px);
  font-weight: 800;
  font-style: italic;
  line-height: 1.5;
  letter-spacing: 0.01em;
}

.section-title {
  font-size: clamp(26px, 3.4vw, 42px);
  line-height: 1.18;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 5px 10px;
  border: 2px solid var(--ink);
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.4;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.eyebrow::before {
  content: "";
  width: 7px;
  height: 7px;
  flex: none;
  background: var(--orange);
}

.num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.02em;
}

.text-muted {
  color: var(--mist);
}

.prose {
  max-width: 38em;
  line-height: 1.85;
}

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

.prose h2,
.prose h3 {
  margin-top: 1.8em;
  margin-bottom: 0.6em;
}

.prose ul,
.prose ol {
  margin: 1em 0 1em 1.3em;
  padding: 0;
}

.prose li + li {
  margin-top: 0.35em;
}

.prose a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--blue);
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

.prose a:hover {
  background: var(--lemon);
}

/* ===== 04. 布局与区块 ===== */
.wrap {
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.section {
  position: relative;
  padding-block: clamp(56px, 8vw, 110px);
}

.section--paper2 {
  background: var(--paper-2);
}

.section--ink {
  background-color: var(--charcoal);
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.045) 1px, transparent 1px);
  background-size: 34px 34px;
  color: var(--paper);
}

.section--ink .eyebrow {
  background: var(--charcoal);
  border-color: var(--paper);
  color: var(--paper);
}

.section--ink .text-muted {
  color: #A9B4C4;
}

.section--ink a {
  color: var(--lemon);
}

.hero-bleed {
  margin-top: calc(var(--header-h) * -1);
  padding-top: calc(var(--header-h) + clamp(32px, 6vw, 72px));
}

.grid {
  display: grid;
  gap: clamp(16px, 2.2vw, 26px);
}

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

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

.grid--split {
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 0.85fr);
  align-items: start;
}

.stack > * + * {
  margin-top: clamp(14px, 2vw, 22px);
}

/* ===== 05. 按钮 ===== */
.btn {
  --btn-bg: var(--orange);
  --btn-fg: var(--ink);
  --btn-bd: var(--ink);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 20px;
  background: var(--btn-bg);
  color: var(--btn-fg);
  border: 2px solid var(--btn-bd);
  border-radius: 0;
  box-shadow: var(--shadow-hard);
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
  letter-spacing: 0.02em;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.14s var(--ease), box-shadow 0.14s var(--ease), background-color 0.14s var(--ease);
}

.btn:hover {
  transform: translate(-1px, -2px);
  box-shadow: 6px 6px 0 rgba(43, 33, 24, 0.9);
}

.btn:active {
  transform: translate(1px, 1px);
  box-shadow: 1px 1px 0 rgba(43, 33, 24, 0.9);
}

.btn--solid {
  --btn-bg: var(--orange);
  --btn-fg: var(--ink);
  --btn-bd: var(--ink);
}

.btn--ghost {
  --btn-bg: transparent;
  --btn-fg: var(--ink);
  --btn-bd: var(--ink);
  box-shadow: none;
}

.btn--ghost:hover {
  background: var(--paper-2);
  box-shadow: none;
}

/* ===== 06. 标签与面板 ===== */
.tag {
  display: inline-block;
  padding: 3px 9px;
  border: 2px solid var(--ink);
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.6;
  letter-spacing: 0.06em;
}

.tag--lemon {
  background: var(--lemon);
  border-color: var(--ink);
  color: var(--ink);
}

.tag--green {
  background: var(--green);
  border-color: var(--ink);
  color: #06270B;
}

.tag--ink {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--paper);
}

.panel {
  position: relative;
  padding: clamp(20px, 3vw, 32px);
  border: 2px solid var(--ink);
  background: var(--paper);
  box-shadow: var(--shadow-card);
}

.panel--stack {
  background: var(--paper-2);
}

.panel--ink {
  background-color: var(--charcoal);
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.05) 1px, transparent 1px);
  background-size: 28px 28px;
  border-color: var(--charcoal);
  color: var(--paper);
  box-shadow: 7px 7px 0 rgba(30, 144, 255, 0.35);
}

.panel--ink a {
  color: var(--lemon);
}

/* ===== 07. 图片容器 ===== */
.media-frame {
  position: relative;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  border: 2px solid var(--ink);
  background: var(--paper-2);
  box-shadow: var(--shadow-card);
}

.media-frame > img,
.media-frame > picture {
  display: block;
  width: 100%;
  height: 100%;
}

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

.media-frame > img,
.media-frame > picture > img {
  object-fit: cover;
  filter: saturate(1.05) contrast(1.05);
  transform: scale(1.01);
  transition: transform 0.45s var(--ease), filter 0.45s var(--ease);
}

.media-frame:hover > img,
.media-frame:hover > picture > img {
  transform: scale(1.045);
  filter: saturate(1.12) contrast(1.08);
}

.media-frame--wide {
  aspect-ratio: 16 / 9;
}

.media-frame--tall {
  aspect-ratio: 3 / 4;
}

.media-frame--square {
  aspect-ratio: 1 / 1;
}

.media-frame__tag {
  position: absolute;
  top: 12px;
  left: -4px;
  z-index: 2;
  padding: 4px 10px;
  border: 2px solid var(--ink);
  background: var(--lemon);
  color: var(--ink);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  line-height: 1.5;
  transform: rotate(-2deg);
}

.media-frame__caption {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 2;
  padding: 9px 14px;
  border-top: 2px solid var(--orange);
  background: rgba(26, 26, 46, 0.86);
  color: var(--paper);
  font-size: 13px;
  line-height: 1.5;
}

.media-stack {
  position: relative;
  padding: 0 18px 18px 0;
}

.media-stack::before {
  content: "";
  position: absolute;
  inset: 18px 0 0 18px;
  border: 2px solid var(--ink);
  background: var(--paper-2);
}

.media-stack .media-frame {
  position: relative;
  z-index: 1;
}

/* ===== 08. 面包屑 ===== */
.breadcrumbs {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.04em;
}

.breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.breadcrumbs__item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  color: var(--mist);
}

.breadcrumbs__item + .breadcrumbs__item::before {
  content: "/";
  color: var(--mist);
}

.breadcrumbs__link {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--paper-line);
  padding-bottom: 1px;
}

.breadcrumbs__link:hover {
  border-bottom-color: var(--orange);
}

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

/* ===== 09. 可展开内容组 ===== */
.disclosure {
  border: 2px solid var(--ink);
  background: var(--paper);
}

.disclosure + .disclosure {
  margin-top: -2px;
}

.disclosure__button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  width: 100%;
  padding: 16px 18px;
  border: 0;
  border-left: 6px solid transparent;
  background: transparent;
  color: var(--ink);
  font-family: var(--font-body);
  font-size: 17px;
  font-weight: 600;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
  transition: background-color 0.18s var(--ease), border-color 0.18s var(--ease);
}

.disclosure__button:hover {
  background: var(--paper-2);
}

.disclosure__button[aria-expanded="true"] {
  border-left-color: var(--orange);
  background: var(--paper-2);
}

.disclosure__icon {
  position: relative;
  flex: none;
  width: 18px;
  height: 18px;
  border: 2px solid var(--ink);
  background: var(--paper);
}

.disclosure__icon::before,
.disclosure__icon::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  background: var(--ink);
  transform: translate(-50%, -50%);
}

.disclosure__icon::before {
  width: 8px;
  height: 2px;
}

.disclosure__icon::after {
  width: 2px;
  height: 8px;
  transition: transform 0.18s var(--ease), opacity 0.18s var(--ease);
}

.disclosure__button[aria-expanded="true"] .disclosure__icon::after {
  transform: translate(-50%, -50%) rotate(90deg);
  opacity: 0;
}

.disclosure__panel {
  padding: 2px 18px 20px 24px;
  border-left: 6px solid var(--orange);
  background: var(--paper-2);
  font-size: 16px;
  line-height: 1.75;
}

.disclosure__panel[hidden] {
  display: none;
}

/* ===== 10. 滚动显现 ===== */
.reveal-ready .reveal {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 0.4s var(--ease), transform 0.4s var(--ease);
}

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

/* ===== 11. 跳转链接 ===== */
.skip-link {
  position: fixed;
  top: 10px;
  left: 10px;
  z-index: 300;
  padding: 10px 18px;
  border: 2px solid var(--lemon);
  background: var(--ink);
  color: var(--paper);
  font-weight: 700;
  text-decoration: none;
  transform: translateY(-180%);
  transition: transform 0.16s var(--ease);
}

.skip-link:focus {
  transform: none;
}

/* ===== 12. 头部 ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 200;
  color: var(--ink);
  background: linear-gradient(180deg, rgba(255, 247, 236, 0.95) 0%, rgba(255, 247, 236, 0.72) 62%, rgba(255, 247, 236, 0) 100%);
  border-bottom: 2px solid transparent;
  transition: background-color 0.18s var(--ease), border-color 0.18s var(--ease), box-shadow 0.18s var(--ease);
}

.site-header[data-scrolled="true"],
.site-header[data-open="true"] {
  background: var(--paper);
  border-bottom-color: var(--ink);
  box-shadow: 0 12px 30px rgba(43, 33, 24, 0.12);
}

.header-progress {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  background: rgba(43, 33, 24, 0.1);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.18s var(--ease);
}

.site-header[data-scrolled="true"] .header-progress {
  opacity: 1;
}

.header-progress__bar {
  display: block;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, var(--orange) 0%, var(--lemon) 55%, var(--blue) 100%);
  transform: scaleX(0);
  transform-origin: 0 50%;
}

.header-shell {
  display: flex;
  align-items: center;
  gap: clamp(12px, 2vw, 30px);
  width: 100%;
  max-width: var(--wrap);
  height: var(--header-h);
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  flex: none;
  min-width: 0;
  color: var(--ink);
  text-decoration: none;
}

.brand__mark {
  position: relative;
  flex: none;
  width: 38px;
  height: 38px;
  border: 2px solid var(--ink);
  background: var(--orange);
  box-shadow: 3px 3px 0 rgba(43, 33, 24, 0.9);
  transform: rotate(-6deg);
}

.brand__mark::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 6px;
  right: 6px;
  height: 2px;
  background: var(--ink);
  transform: translateY(-50%) rotate(-28deg);
}

.brand__mark-dot {
  position: absolute;
  top: 5px;
  right: 5px;
  width: 9px;
  height: 9px;
  border: 1.5px solid var(--ink);
  background: var(--blue);
}

.brand__text {
  display: flex;
  flex-direction: column;
  gap: 1px;
  min-width: 0;
}

.brand__name {
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 700;
  line-height: 1.2;
  letter-spacing: 0.04em;
}

.brand__tag {
  font-family: var(--font-mono);
  font-size: 10.5px;
  line-height: 1.4;
  letter-spacing: 0.06em;
  color: var(--mist);
  white-space: nowrap;
}

.site-nav {
  flex: 1 1 auto;
  min-width: 0;
  display: flex;
  justify-content: center;
}

.site-nav__list {
  display: flex;
  align-items: center;
  gap: 2px;
  margin: 0;
  padding: 0;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.site-nav__list::-webkit-scrollbar {
  display: none;
}

.site-nav__item {
  flex: none;
}

.site-nav__link {
  display: inline-block;
  padding: 9px 12px;
  border-bottom: 3px solid transparent;
  color: var(--ink);
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  text-decoration: none;
  transition: color 0.16s var(--ease), border-color 0.16s var(--ease), background-color 0.16s var(--ease);
}

.site-nav__link:hover {
  color: var(--brick);
  border-bottom-color: var(--orange);
}

.site-nav__link[aria-current="page"] {
  color: var(--ink);
  border-bottom-color: var(--orange);
  background: linear-gradient(180deg, transparent 55%, rgba(255, 217, 61, 0.6) 55%);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-left: auto;
}

.header-actions .btn {
  padding: 9px 14px;
  font-size: 14px;
  box-shadow: 2px 2px 0 rgba(43, 33, 24, 0.85);
}

.nav-toggle {
  display: none;
  position: relative;
  align-items: center;
  justify-content: center;
  gap: 8px;
  width: 48px;
  height: 42px;
  padding: 0;
  border: 2px solid var(--ink);
  background: var(--ink);
  color: var(--paper);
  cursor: pointer;
  transition: background-color 0.16s var(--ease), border-color 0.16s var(--ease);
}

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

.nav-toggle__bars {
  display: grid;
  gap: 4px;
  width: 18px;
}

.nav-toggle__bars span {
  display: block;
  height: 2px;
  background: var(--paper);
  transition: transform 0.18s var(--ease), opacity 0.18s var(--ease);
}

.nav-toggle__label {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  clip-path: inset(50%);
  white-space: nowrap;
  border: 0;
}

.site-header[data-open="true"] .nav-toggle {
  background: var(--orange);
  border-color: var(--ink);
}

.site-header[data-open="true"] .nav-toggle__bars span {
  background: var(--ink);
}

.site-header[data-open="true"] .nav-toggle__bars span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.site-header[data-open="true"] .nav-toggle__bars span:nth-child(2) {
  opacity: 0;
}

.site-header[data-open="true"] .nav-toggle__bars span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* ===== 13. 页脚 ===== */
.site-footer {
  position: relative;
  margin-top: clamp(72px, 10vw, 140px);
  background-color: var(--charcoal);
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.045) 1px, transparent 1px);
  background-size: 32px 32px;
  color: var(--paper);
}

.footer-stripe {
  height: 6px;
  background: linear-gradient(90deg, var(--orange) 0 55%, var(--lemon) 55% 72%, var(--blue) 72% 100%);
}

.footer-shell {
  display: grid;
  grid-template-columns: minmax(240px, 1.4fr) minmax(0, 2.1fr) minmax(240px, 1.2fr);
  gap: clamp(24px, 3vw, 48px);
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: clamp(40px, 6vw, 72px) var(--gutter) 32px;
}

.footer-lead {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 18px;
}

.brand--footer {
  color: var(--paper);
}

.brand--footer .brand__mark {
  border-color: var(--paper);
  box-shadow: 3px 3px 0 rgba(255, 107, 53, 0.6);
}

.brand--footer .brand__tag {
  color: rgba(255, 247, 236, 0.7);
}

.footer-summary {
  max-width: 32ch;
  color: rgba(255, 247, 236, 0.78);
  font-size: 15px;
  line-height: 1.75;
}

.footer-cols {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
}

.footer-col__title {
  display: flex;
  align-items: center;
  gap: 8px;
  margin: 0;
  color: var(--lemon);
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.footer-col__title::before {
  content: "";
  width: 8px;
  height: 8px;
  flex: none;
  background: var(--orange);
}

.footer-list {
  margin: 14px 0 0;
  padding: 0;
  list-style: none;
}

.footer-list li + li {
  margin-top: 8px;
}

.footer-link {
  display: inline-block;
  padding-block: 2px;
  border-bottom: 1px solid transparent;
  color: rgba(255, 247, 236, 0.84);
  font-size: 15px;
  line-height: 1.6;
  text-decoration: none;
  transition: color 0.16s var(--ease), border-color 0.16s var(--ease);
}

.footer-link:hover {
  color: var(--lemon);
  border-bottom-color: var(--orange);
}

.footer-contact {
  padding-left: 20px;
  border-left: 2px solid rgba(255, 247, 236, 0.2);
}

.footer-contact__row {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr);
  gap: 10px;
  padding: 9px 0;
  border-bottom: 1px dashed rgba(255, 247, 236, 0.16);
}

.footer-contact__row:last-child {
  border-bottom: 0;
}

.footer-contact__label {
  color: #93A1B5;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  line-height: 1.9;
  text-transform: uppercase;
}

.footer-contact__value {
  color: var(--paper);
  font-size: 14px;
  line-height: 1.65;
  word-break: break-word;
}

.footer-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px 28px;
  width: 100%;
  max-width: var(--wrap);
  margin-inline: auto;
  padding: 20px var(--gutter) 34px;
  border-top: 1px solid rgba(255, 247, 236, 0.16);
  color: rgba(255, 247, 236, 0.72);
  font-size: 12.5px;
  line-height: 1.7;
}

.footer-meta__line {
  font-family: var(--font-mono);
  letter-spacing: 0.03em;
}

.footer-note {
  max-width: 52ch;
}

/* ===== 14. 平板与移动端 ===== */
@media (max-width: 1080px) {
  .site-nav {
    position: fixed;
    top: var(--header-h);
    left: 0;
    right: 0;
    display: block;
    flex: none;
    max-height: calc(100vh - var(--header-h));
    max-height: calc(100dvh - var(--header-h));
    overflow-y: auto;
    padding: 16px var(--gutter) 26px;
    border-bottom: 2px solid var(--ink);
    background: var(--paper);
    box-shadow: 0 24px 50px rgba(43, 33, 24, 0.22);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.2s var(--ease), transform 0.2s var(--ease), visibility 0.2s;
  }

  .site-header[data-open="true"] .site-nav {
    opacity: 1;
    visibility: visible;
    transform: none;
  }

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

  .site-nav__item {
    border-bottom: 1px dashed rgba(43, 33, 24, 0.28);
  }

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

  .site-nav__link {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 12px;
    padding: 15px 6px;
    border-bottom: 0;
    font-size: 17px;
  }

  .site-nav__link::after {
    content: "→";
    color: var(--orange);
    font-family: var(--font-mono);
    opacity: 0.85;
  }

  .site-nav__link[aria-current="page"] {
    padding-left: 14px;
    border-bottom: 0;
    background: var(--paper-2);
    box-shadow: inset 5px 0 0 var(--orange);
  }

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

  .header-actions .btn--ghost {
    display: none;
  }

  .brand__tag {
    display: none;
  }

  body.nav-open {
    overflow: hidden;
  }

  .footer-shell {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 32px;
  }

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

  .footer-cols {
    grid-column: 1 / -1;
    padding-top: 24px;
    border-top: 1px solid rgba(255, 247, 236, 0.16);
  }

  .footer-contact {
    grid-column: 1 / -1;
    padding-top: 22px;
    padding-left: 0;
    border-top: 1px solid rgba(255, 247, 236, 0.16);
    border-left: 0;
  }
}

@media (max-width: 980px) {
  .grid--3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

@media (max-width: 720px) {
  body {
    font-size: 16px;
  }

  .header-shell {
    gap: 10px;
  }

  .brand__name {
    font-size: 18px;
  }

  .brand__mark {
    width: 34px;
    height: 34px;
  }

  .header-actions .btn {
    padding: 8px 11px;
    font-size: 13px;
  }

  .btn {
    padding: 11px 16px;
  }

  .footer-cols {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px;
  }
}

@media (max-width: 640px) {
  .grid--2,
  .grid--3,
  .grid--split {
    grid-template-columns: minmax(0, 1fr);
  }

  .footer-shell {
    grid-template-columns: minmax(0, 1fr);
    gap: 26px;
  }

  .footer-lead,
  .footer-cols,
  .footer-contact {
    grid-column: auto;
  }

  .footer-meta {
    flex-direction: column;
    align-items: flex-start;
  }

  .disclosure__button {
    font-size: 16px;
    padding: 14px 14px;
  }

  .disclosure__panel {
    padding: 2px 14px 18px 20px;
  }
}

@media (max-width: 420px) {
  .footer-cols {
    grid-template-columns: minmax(0, 1fr);
  }
}

/* ===== 15. 动效降级 ===== */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .site-header,
  .site-nav,
  .btn,
  .media-frame > img,
  .media-frame > picture > img {
    transition: none;
  }

  .btn:hover {
    transform: none;
  }

  .media-frame > img,
  .media-frame > picture > img {
    transform: none;
  }

  .media-frame:hover > img,
  .media-frame:hover > picture > img {
    transform: none;
  }

  .reveal-ready .reveal {
    opacity: 1;
    transform: none;
    transition: opacity 0.2s linear;
  }
}