:root {
  --ink-900: #0f1e2e;
  --ink-800: #16283a;
  --ink-700: #1c3040;
  --ink-600: #24405a;
  --paper: #f5f1e8;
  --paper-dim: #c9c2b4;
  --paper-soft: #ded8cb;
  --amber: #e2762c;
  --amber-soft: #f0a06a;
  --azure: #7fb2d9;
  --line: #33495e;
  --line-soft: #2a3d50;
  --radius: 6px;
  --radius-sm: 4px;
  --shell: 1120px;
  --gap: 24px;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", "Noto Sans CJK SC", system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "SFMono-Regular", "JetBrains Mono", Consolas, "Liberation Mono", Menlo, monospace;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

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

body.site-body {
  margin: 0;
  background-color: var(--ink-900);
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  font-weight: 400;
  overflow-wrap: break-word;
}

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

a {
  color: var(--azure);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-thickness: 1px;
}

a:hover {
  color: var(--amber-soft);
  text-decoration-thickness: 2px;
}

a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 2px;
  box-shadow: 0 0 0 4px rgba(226, 118, 44, 0.28);
  border-radius: var(--radius-sm);
}

h1,
h2,
h3,
h4 {
  margin: 0;
  font-weight: 700;
  line-height: 1.4;
  color: var(--paper);
}

p {
  margin: 0;
}

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

figure {
  margin: 0;
}

dl,
dd,
dt {
  margin: 0;
}

.skip-link {
  position: absolute;
  left: 16px;
  top: -60px;
  z-index: 60;
  background-color: var(--amber);
  color: var(--ink-900);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  text-decoration: none;
  transition: top 0.18s ease;
}

.skip-link:focus {
  top: 12px;
  color: var(--ink-900);
}

/* ============================================================
   layout — 全站骨架
   ============================================================ */

.site-header {
  background-color: var(--ink-800);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 40;
}

.header-inner {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: var(--paper);
  font-size: 18px;
  font-weight: 700;
  line-height: 1.3;
}

.brand:hover {
  color: var(--paper);
  text-decoration: underline;
  text-decoration-thickness: 2px;
}

.brand-mark {
  width: 26px;
  height: 26px;
  flex: 0 0 26px;
  border-radius: var(--radius-sm);
  background-color: var(--amber);
  position: relative;
}

.brand-mark::after {
  content: "";
  position: absolute;
  inset: 7px;
  background-color: var(--ink-900);
  clip-path: polygon(0 0, 100% 50%, 0 100%);
}

.brand-text {
  white-space: nowrap;
}

.site-nav {
  flex: 1 1 auto;
  display: flex;
  justify-content: flex-end;
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 8px 14px;
  background-color: transparent;
  color: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
}

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

.nav-toggle-icon {
  width: 18px;
  height: 12px;
  position: relative;
  flex: 0 0 18px;
  border-top: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
}

.nav-toggle-icon::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  border-top: 2px solid currentColor;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
  flex-wrap: wrap;
}

.nav-link {
  display: inline-block;
  padding: 10px 12px;
  min-height: 44px;
  color: var(--paper);
  font-size: 15px;
  font-weight: 500;
  text-decoration: none;
  border-bottom: 2px solid transparent;
  border-radius: var(--radius-sm);
}

.nav-link:hover {
  color: var(--amber-soft);
  border-bottom-color: var(--amber-soft);
  text-decoration: underline;
}

.nav-link.is-current {
  font-weight: 700;
  color: var(--paper);
  border-bottom-color: var(--amber);
  text-decoration: underline;
  text-decoration-color: var(--amber);
}

.nav-link-boundary {
  border: 1px solid var(--line);
  margin-left: 6px;
}

.nav-link-boundary:hover {
  border-color: var(--amber-soft);
}

.site-main {
  display: block;
}

.inner-main {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 20px 56px;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 20px 0 6px;
  font-size: 14px;
  color: var(--paper-dim);
}

.breadcrumb a {
  color: var(--azure);
}

.breadcrumb-sep {
  color: var(--line);
}

.breadcrumb-current {
  color: var(--paper-dim);
}

.page-header {
  padding: 6px 0 26px;
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: 32px;
}

.page-title {
  font-size: 32px;
  line-height: 1.35;
  color: var(--paper);
}

.page-description {
  margin-top: 12px;
  max-width: 780px;
  color: var(--paper-dim);
  font-size: 16px;
}

.section {
  margin-bottom: 48px;
}

.section-head {
  margin-bottom: 22px;
  border-left: 3px solid var(--amber);
  padding-left: 14px;
}

.section-title {
  font-size: 22px;
  line-height: 1.4;
  color: var(--paper);
}

.section-sub,
.section-intro,
.section-desc,
.section-text {
  margin-top: 8px;
  max-width: 800px;
  color: var(--paper-dim);
  font-size: 15.5px;
}

.section-text + .rule-list,
.section-text + .channel-grid,
.section-text + .topic-list,
.section-text + .advice-list,
.section-text + .step-list {
  margin-top: 20px;
}

.section-more {
  margin-top: 20px;
  font-size: 15px;
}

.section-note {
  margin-top: 20px;
  color: var(--paper-dim);
  font-size: 15px;
}

.section-note a {
  margin-right: 14px;
  display: inline-block;
}

.link-inline {
  display: inline-block;
  color: var(--azure);
  font-weight: 600;
  font-size: 15px;
}

.link-inline:hover {
  color: var(--amber-soft);
}

/* ============================================================
   components — 通用组件
   ============================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 10px 22px;
  border-radius: var(--radius);
  font-size: 16px;
  font-weight: 700;
  text-decoration: none;
  border: 1px solid transparent;
  cursor: pointer;
}

.btn-primary {
  background-color: var(--amber);
  color: var(--ink-900);
  border-color: var(--amber);
}

.btn-primary:hover {
  background-color: var(--amber-soft);
  border-color: var(--amber-soft);
  color: var(--ink-900);
  text-decoration: underline;
}

.btn-ghost {
  background-color: transparent;
  color: var(--paper);
  border-color: var(--paper-dim);
}

.btn-ghost:hover {
  border-color: var(--amber);
  color: var(--amber-soft);
  text-decoration: underline;
}

.step-list {
  counter-reset: step;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}

.step-item {
  position: relative;
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px 20px 18px 58px;
}

.step-item::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 18px;
  top: 18px;
  width: 26px;
  height: 26px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--amber);
  color: var(--ink-900);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.step-item .step-name,
.step-item .step-title {
  font-size: 17px;
  color: var(--paper);
}

.step-item .step-desc,
.step-item .step-text {
  margin-top: 6px;
  color: var(--paper-dim);
  font-size: 15px;
}

.faq-list {
  display: grid;
  gap: 12px;
}

.faq-item {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  overflow: hidden;
}

.faq-item[open] {
  border-color: var(--amber);
}

.faq-question {
  cursor: pointer;
  list-style: none;
  padding: 16px 48px 16px 18px;
  font-size: 16px;
  font-weight: 600;
  color: var(--paper);
  position: relative;
  min-height: 44px;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: "展开";
  position: absolute;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 13px;
  font-weight: 600;
  color: var(--amber-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 2px 8px;
}

.faq-item[open] .faq-question::after {
  content: "收起";
  border-color: var(--amber);
}

.faq-question:hover {
  color: var(--amber-soft);
  text-decoration: underline;
}

.faq-answer {
  padding: 0 18px 18px;
  border-top: 1px solid var(--line-soft);
  margin-top: 2px;
  padding-top: 14px;
}

.faq-answer p {
  color: var(--paper-dim);
  font-size: 15px;
}

/* ============================================================
   pages — 首页
   ============================================================ */

.home-main {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 20px 56px;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  gap: 36px;
  align-items: start;
  padding: 40px 0 48px;
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: 44px;
}

.hero-text {
  min-width: 0;
}

.hero-eyebrow {
  display: inline-block;
  font-size: 14px;
  font-weight: 600;
  color: var(--amber-soft);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  padding: 4px 12px;
  margin-bottom: 16px;
}

.hero-title {
  font-size: 32px;
  line-height: 1.35;
  color: var(--paper);
}

.hero-desc {
  margin-top: 16px;
  max-width: 620px;
  color: var(--paper-dim);
  font-size: 16.5px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 26px;
}

.hero-quick {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 24px;
}

.hero-quick li {
  min-width: 0;
}

.hero-quick a {
  display: inline-block;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-size: 14.5px;
  color: var(--paper);
  text-decoration: none;
}

.hero-quick a:hover {
  border-color: var(--amber);
  color: var(--amber-soft);
  text-decoration: underline;
}

.hero-media {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--ink-700);
}

.hero-media img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.hero-media figcaption {
  padding: 12px 16px;
  font-size: 14px;
  color: var(--paper-dim);
  border-top: 1px solid var(--line-soft);
}

.path-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
}

.path-card {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 20px;
  display: flex;
  flex-direction: column;
}

.path-card:hover {
  border-color: var(--amber);
}

.path-name {
  font-size: 18px;
  color: var(--paper);
}

.path-for {
  margin-top: 10px;
  color: var(--paper-dim);
  font-size: 15px;
}

.path-note {
  margin-top: 8px;
  color: var(--paper-soft);
  font-size: 14.5px;
}

.path-card .link-inline {
  margin-top: 16px;
}

.channel-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
}

.channel-card {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.channel-card:hover {
  border-color: var(--amber);
}

.channel-media,
.channel-figure {
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  overflow: hidden;
  margin-bottom: 14px;
}

.channel-media img,
.channel-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.channel-name {
  font-size: 18px;
  color: var(--paper);
}

.channel-scope {
  margin-top: 10px;
  color: var(--paper-dim);
  font-size: 15px;
}

.channel-for,
.channel-scene,
.channel-direction {
  margin-top: 8px;
  color: var(--paper-soft);
  font-size: 14.5px;
}

.channel-card .link-inline,
.channel-link {
  margin-top: 16px;
  display: inline-block;
  color: var(--azure);
  font-weight: 600;
  font-size: 15px;
}

.channel-card .link-inline:hover,
.channel-link:hover {
  color: var(--amber-soft);
}

.topic-list {
  display: grid;
  gap: 16px;
}

.topic-card {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 20px;
}

.topic-card:hover {
  border-color: var(--amber);
}

.topic-name,
.topic-title {
  font-size: 18px;
  color: var(--paper);
}

.topic-scope {
  margin-top: 10px;
  color: var(--paper-dim);
  font-size: 15px;
}

.topic-order {
  margin-top: 8px;
  color: var(--paper-soft);
  font-size: 14.5px;
}

.topic-card .link-inline {
  margin-top: 16px;
}

.ranking-list {
  counter-reset: rank;
  display: grid;
  gap: 12px;
}

.ranking-item {
  display: grid;
  grid-template-columns: 52px minmax(0, 1fr);
  gap: 16px;
  align-items: start;
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 16px 18px;
}

.ranking-item:hover {
  border-color: var(--amber);
}

.ranking-no {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 24px;
  font-weight: 700;
  color: var(--amber);
  line-height: 1.2;
}

.ranking-body {
  min-width: 0;
}

.ranking-name {
  font-size: 17px;
  color: var(--paper);
}

.ranking-reason {
  margin-top: 6px;
  color: var(--paper-dim);
  font-size: 15px;
}

.boundary-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.boundary-block {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-left: 3px solid var(--amber);
  border-radius: var(--radius);
  padding: 20px;
}

.boundary-name {
  font-size: 17px;
  color: var(--paper);
}

.boundary-text {
  margin-top: 10px;
  color: var(--paper-dim);
  font-size: 15px;
}

/* ============================================================
   pages — 频道分类
   ============================================================ */

.rule-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
}

.rule-item {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px;
}

.rule-name {
  font-size: 17px;
  color: var(--paper);
}

.rule-desc {
  margin-top: 8px;
  color: var(--paper-dim);
  font-size: 15px;
}

.advice-list {
  counter-reset: advice;
  display: grid;
  gap: 14px;
}

.advice-item {
  position: relative;
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px 20px 18px 58px;
}

.advice-item::before {
  counter-increment: advice;
  content: counter(advice);
  position: absolute;
  left: 18px;
  top: 18px;
  width: 26px;
  height: 26px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--amber);
  color: var(--ink-900);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.advice-goal {
  font-size: 17px;
  color: var(--paper);
}

.advice-body {
  margin-top: 6px;
  color: var(--paper-dim);
  font-size: 15px;
}

.advice-footer {
  margin-top: 20px;
  font-size: 15px;
}

.advice-footer a {
  margin-right: 16px;
  display: inline-block;
}

/* ============================================================
   pages — 专题片单
   ============================================================ */

.principle-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
  margin-top: 20px;
}

.principle-item {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px;
}

.principle-title {
  font-size: 17px;
  color: var(--paper);
}

.principle-text {
  margin-top: 8px;
  color: var(--paper-dim);
  font-size: 15px;
}

.section-topic-list .topic-card {
  display: grid;
  grid-template-columns: minmax(0, 300px) minmax(0, 1fr);
  gap: 22px;
  align-items: start;
  padding: 18px;
}

.topic-media {
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.topic-media img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.topic-body {
  min-width: 0;
}

.topic-label {
  display: inline-block;
  min-width: 68px;
  color: var(--amber-soft);
  font-weight: 600;
  font-size: 14px;
}

.topic-direction {
  margin-top: 8px;
  color: var(--paper-soft);
  font-size: 14.5px;
}

.topic-link {
  display: inline-block;
  margin-top: 16px;
  color: var(--azure);
  font-weight: 600;
  font-size: 15px;
}

.topic-link:hover {
  color: var(--amber-soft);
}

/* ============================================================
   pages — 观看指引
   ============================================================ */

.guide-prep,
.guide-device,
.guide-loading,
.guide-related {
  margin-bottom: 48px;
}

.guide-figure {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--ink-700);
  margin-bottom: 24px;
}

.guide-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 21 / 9;
  object-fit: cover;
}

.figure-caption {
  padding: 12px 16px;
  font-size: 14px;
  color: var(--paper-dim);
  border-top: 1px solid var(--line-soft);
}

.device-compare {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
}

.device-col {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 20px;
  min-width: 0;
}

.device-col-title {
  font-size: 17px;
  color: var(--paper);
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line-soft);
}

.device-list {
  display: grid;
  gap: 14px;
  margin-top: 16px;
}

.device-item {
  min-width: 0;
}

.device-name {
  font-size: 15.5px;
  color: var(--amber-soft);
}

.device-note {
  margin-top: 4px;
  color: var(--paper-dim);
  font-size: 14.5px;
}

.related-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 16px;
}

.related-item {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px;
}

.related-item:hover {
  border-color: var(--amber);
}

.related-link {
  font-size: 16px;
  font-weight: 600;
}

.related-note {
  margin-top: 8px;
  color: var(--paper-dim);
  font-size: 14.5px;
}

/* ============================================================
   pages — 内容边界与反馈
   ============================================================ */

.scope-layout {
  display: grid;
  grid-template-columns: minmax(0, 340px) minmax(0, 1fr);
  gap: 26px;
  align-items: start;
}

.scope-figure {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--ink-700);
}

.scope-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 4 / 3;
  object-fit: cover;
}

.scope-figure figcaption {
  padding: 12px 16px;
  font-size: 14px;
  color: var(--paper-dim);
  border-top: 1px solid var(--line-soft);
}

.scope-list {
  display: grid;
  gap: 14px;
  min-width: 0;
}

.scope-item {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-left: 3px solid var(--azure);
  border-radius: var(--radius);
  padding: 16px 18px;
}

.scope-item-title {
  font-size: 16.5px;
  color: var(--paper);
}

.scope-item-text {
  margin-top: 6px;
  color: var(--paper-dim);
  font-size: 15px;
}

.scope-note {
  margin-top: 22px;
  font-size: 15px;
}

.scope-note a {
  margin-right: 16px;
  display: inline-block;
}

.exclusion-list {
  display: grid;
  gap: 12px;
}

.exclusion-item {
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 16px 18px;
}

.exclusion-term {
  font-size: 16.5px;
  font-weight: 700;
  color: var(--amber-soft);
}

.exclusion-desc {
  margin-top: 6px;
  color: var(--paper-dim);
  font-size: 15px;
}

.feedback-list {
  counter-reset: feedback;
  display: grid;
  gap: 14px;
}

.feedback-item {
  position: relative;
  background-color: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  padding: 18px 20px 18px 58px;
}

.feedback-item::before {
  counter-increment: feedback;
  content: counter(feedback);
  position: absolute;
  left: 18px;
  top: 18px;
  width: 26px;
  height: 26px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--amber);
  color: var(--ink-900);
  border-radius: var(--radius-sm);
  font-size: 14px;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.feedback-item-title {
  font-size: 17px;
  color: var(--paper);
}

.feedback-item-text {
  margin-top: 6px;
  color: var(--paper-dim);
  font-size: 15px;
}

.feedback-note {
  margin-top: 20px;
  color: var(--paper-dim);
  font-size: 15px;
}

/* ============================================================
   pages — 404
   ============================================================ */

.site-error .error-main {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 0 20px 56px;
}

.error-block {
  padding: 64px 0 32px;
  max-width: 720px;
}

.error-code {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 56px;
  font-weight: 700;
  color: var(--amber);
  line-height: 1.1;
}

.error-title {
  margin-top: 12px;
  font-size: 32px;
  line-height: 1.35;
  color: var(--paper);
}

.error-text {
  margin-top: 14px;
  color: var(--paper-dim);
  font-size: 16px;
}

.error-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 26px;
}

.error-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
  margin-top: 28px;
  padding-top: 22px;
  border-top: 1px solid var(--line-soft);
  font-size: 15px;
}

/* ============================================================
   layout — 页脚
   ============================================================ */

.site-footer {
  background-color: var(--ink-800);
  border-top: 1px solid var(--line);
  margin-top: 24px;
}

.footer-inner {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 40px 20px 28px;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 28px;
}

.footer-col {
  min-width: 0;
}

.footer-title {
  font-size: 16px;
  color: var(--paper);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: 14px;
}

.footer-text {
  color: var(--paper-dim);
  font-size: 14.5px;
}

.footer-list {
  display: grid;
  gap: 8px;
}

.footer-list a {
  display: inline-block;
  min-height: 32px;
  font-size: 14.5px;
  color: var(--azure);
}

.footer-list a:hover {
  color: var(--amber-soft);
}

.footer-bottom {
  max-width: var(--shell);
  margin: 0 auto;
  padding: 18px 20px 28px;
  border-top: 1px solid var(--line-soft);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

.footer-copy {
  color: var(--paper-dim);
  font-size: 14px;
}

.back-to-top {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  color: var(--paper);
  font-size: 14.5px;
  font-weight: 600;
  text-decoration: none;
}

.back-to-top:hover {
  border-color: var(--amber);
  color: var(--amber-soft);
  text-decoration: underline;
}

.back-to-top-icon {
  width: 12px;
  height: 12px;
  flex: 0 0 12px;
  border-top: 2px solid currentColor;
  border-left: 2px solid currentColor;
  transform: rotate(45deg);
}

/* ============================================================
   responsive
   ============================================================ */

@media (max-width: 768px) {
  .header-inner {
    padding: 10px 16px;
  }

  .site-nav {
    flex: 0 0 auto;
  }

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

  .nav-list {
    display: none;
    width: 100%;
    flex-direction: column;
    align-items: stretch;
    gap: 2px;
    padding-top: 10px;
    border-top: 1px solid var(--line-soft);
    margin-top: 8px;
  }

  .nav-list.is-open {
    display: flex;
  }

  .nav-link {
    display: block;
    padding: 12px 14px;
    border-bottom: 1px solid var(--line-soft);
    border-radius: 0;
  }

  .nav-link-boundary {
    margin-left: 0;
    margin-top: 8px;
    border-radius: var(--radius-sm);
  }

  .inner-main,
  .home-main,
  .site-error .error-main {
    padding: 0 16px 44px;
  }

  .hero {
    grid-template-columns: minmax(0, 1fr);
    gap: 26px;
    padding: 28px 0 34px;
    margin-bottom: 34px;
  }

  .hero-title,
  .page-title,
  .error-title {
    font-size: 26px;
  }

  .section {
    margin-bottom: 38px;
  }

  .section-title {
    font-size: 20px;
  }

  .section-topic-list .topic-card {
    grid-template-columns: minmax(0, 1fr);
    gap: 16px;
  }

  .scope-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px;
  }

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

  .footer-inner {
    padding: 32px 16px 22px;
    gap: 22px;
  }

  .footer-bottom {
    padding: 16px 16px 26px;
  }
}

@media (max-width: 480px) {
  body.site-body {
    font-size: 15.5px;
  }

  .brand {
    font-size: 16.5px;
  }

  .hero-title,
  .page-title,
  .error-title {
    font-size: 24px;
  }

  .hero-actions,
  .error-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    width: 100%;
  }

  .hero-quick {
    gap: 8px;
  }

  .step-item,
  .advice-item,
  .feedback-item {
    padding-left: 20px;
    padding-top: 54px;
  }

  .ranking-item {
    grid-template-columns: 40px minmax(0, 1fr);
    gap: 12px;
  }

  .ranking-no {
    font-size: 20px;
  }

  .error-code {
    font-size: 44px;
  }

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

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .skip-link {
    transition: none;
  }
}