/* ==========================================================================
   ao3 官网入口 · 设计系统样式表
   风格基准：暖米色纸感底色 + 近黑文字 + 赤陶色强调 + 无阴影 + 大圆角
   --------------------------------------------------------------------------
   目录
   01. 设计变量
   02. 基础重置与排版
   03. 布局骨架
   04. 顶部导航
   05. 首屏
   06. 按钮与标签
   07. 卡片与深色容器
   08. 入口列表与筛选
   09. 步骤 / 清单 / 双栏
   10. 时间线 / 表格 / 数据
   11. 常见问题折叠
   12. 内页正文排版
   13. 页脚与广告位
   14. 工具类与响应式
   15. 动效与打印
   ========================================================================== */

/* 01. 设计变量 ----------------------------------------------------------- */
:root {
  --bg: #faf9f5;
  --ink: #141413;
  --ink-soft: #3a3934;
  --card: #e3dacc;
  --card-soft: #f2eee2;
  --accent: #d97757;
  --accent-ink: #a8482a;      /* 小字号可读的赤陶色 */
  --meta: #6f6d65;            /* 元信息文字，保证对比度 */
  --muted: #b0aea5;           /* 仅用于分隔线与深色底上的次要文字 */
  --line: #dcd7ca;
  --line-strong: #b0aea5;
  --white: #ffffff;

  --radius-s: 8px;
  --radius-m: 12px;
  --radius-l: 16px;
  --radius-xl: 24px;

  --font-serif: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia,
    "Songti SC", "Noto Serif SC", "Source Han Serif SC", "SimSun", serif;
  --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", Roboto, "Noto Sans SC",
    sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;

  --shell: 1320px;
  --pad: 48px;
  --section-y: 96px;
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: 96px;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img,
svg {
  max-width: 100%;
  height: auto;
}

h1,
h2,
h3,
h4 {
  margin: 0;
  font-weight: 700;
  line-height: 1.25;
  letter-spacing: -0.01em;
}

h1 {
  font-family: var(--font-serif);
  font-weight: 700;
}

p {
  margin: 0 0 16px;
}

p:last-child {
  margin-bottom: 0;
}

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

a:hover {
  border-bottom-color: var(--ink);
}

ul,
ol {
  margin: 0 0 16px;
  padding-left: 1.25em;
}

li {
  margin: 0 0 8px;
}

li:last-child {
  margin-bottom: 0;
}

strong {
  font-weight: 700;
}

small {
  font-size: 12px;
  line-height: 1.5;
}

hr {
  border: 0;
  border-top: 1px solid var(--line);
  margin: 48px 0;
}

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

/* 保证 hidden 属性优先于组件自身的 display 声明 */
[hidden] {
  display: none !important;
}

:focus-visible {
  outline: 2px solid var(--ink);
  outline-offset: 3px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 200;
  padding: 12px 20px;
  background: var(--ink);
  color: var(--bg);
  border-radius: 0 0 var(--radius-s) 0;
}

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

/* 03. 布局骨架 ----------------------------------------------------------- */
.shell {
  width: 100%;
  max-width: var(--shell);
  margin: 0 auto;
  padding-left: var(--pad);
  padding-right: var(--pad);
}

.section {
  padding-top: var(--section-y);
  padding-bottom: var(--section-y);
}

.section--tight {
  padding-top: 64px;
  padding-bottom: 64px;
}

.section--flush-bottom {
  padding-bottom: 0;
}

.section-rule {
  border-top: 1px solid var(--line);
}

.section-head {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 32px;
  margin-bottom: 48px;
}

.section-head__text {
  max-width: 720px;
}

.section-head h2 {
  font-size: clamp(24px, 2.6vw, 32px);
  margin-bottom: 12px;
}

.section-head p {
  color: var(--ink-soft);
  max-width: 62ch;
  margin-bottom: 0;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 16px;
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--meta);
}

.eyebrow::before {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
  flex: none;
}

.lead {
  font-size: 18px;
  line-height: 1.7;
  color: var(--ink-soft);
  max-width: 62ch;
}

.text-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease;
}

.text-link:hover {
  border-bottom-color: var(--ink);
}

.text-link::after {
  content: "→";
  display: inline-block;
  transition: transform 0.2s ease;
}

.text-link:hover::after {
  transform: translateX(4px);
}

/* 04. 顶部导航 ----------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(250, 249, 245, 0.96);
  border-bottom: 1px solid var(--line);
  -webkit-backdrop-filter: saturate(180%) blur(8px);
  backdrop-filter: saturate(180%) blur(8px);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  min-height: 76px;
}

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

.brand-mark {
  display: grid;
  place-items: center;
  width: 36px;
  height: 36px;
  border-radius: var(--radius-s);
  background: var(--accent);
  color: var(--ink);
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 700;
  line-height: 1;
  padding-bottom: 2px;
}

.brand-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.brand-text strong {
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.01em;
}

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

.site-nav a:not(.btn) {
  position: relative;
  padding: 8px 12px;
  font-size: 15px;
  color: var(--ink-soft);
  border-radius: var(--radius-s);
  transition: color 0.2s ease, background-color 0.2s ease;
}

.site-nav a:not(.btn)::after {
  content: "";
  position: absolute;
  left: 12px;
  right: 12px;
  bottom: 2px;
  height: 1px;
  background: var(--ink);
  transform: scaleX(0);
  transition: transform 0.2s ease;
}

.site-nav a:not(.btn):hover {
  color: var(--ink);
}

.site-nav a:not(.btn):hover::after,
.site-nav a[aria-current="page"]::after {
  transform: scaleX(1);
}

.site-nav a[aria-current="page"] {
  color: var(--ink);
  font-weight: 500;
}

.nav-cta {
  margin-left: 12px;
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-s);
  background: transparent;
  cursor: pointer;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 5px;
}

.nav-toggle span {
  display: block;
  width: 18px;
  height: 1px;
  background: var(--ink);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.nav-toggle[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle[aria-expanded="true"] span:nth-child(2) {
  opacity: 0;
}

.nav-toggle[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* 05. 首屏 --------------------------------------------------------------- */
.hero {
  padding-top: 80px;
  padding-bottom: 80px;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.08fr) minmax(0, 0.92fr);
  gap: 64px;
  align-items: start;
}

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

.hero-grid--single .hero-lead {
  max-width: 66ch;
}

.hero-title {
  font-size: clamp(40px, 5.6vw, 72px);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin-bottom: 24px;
}

.hero-title::after {
  content: "。";
  color: var(--accent);
}

.hero-lead {
  font-size: 18px;
  line-height: 1.75;
  color: var(--ink-soft);
  max-width: 56ch;
  margin-bottom: 32px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  margin-bottom: 40px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  border-top: 1px solid var(--line);
  padding-top: 24px;
  max-width: 560px;
}

.hero-stats dt {
  font-family: var(--font-serif);
  font-size: 30px;
  font-weight: 700;
  line-height: 1.1;
}

.hero-stats dd {
  margin: 6px 0 0;
  font-size: 13px;
  color: var(--meta);
  line-height: 1.5;
}

.notice-bar {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 16px 20px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-m);
  font-size: 14px;
  line-height: 1.65;
  color: var(--ink-soft);
  background: transparent;
}

.notice-bar__icon {
  flex: none;
  display: grid;
  place-items: center;
  width: 20px;
  height: 20px;
  margin-top: 2px;
  border-radius: 50%;
  background: var(--accent);
  color: var(--white);
  font-size: 12px;
  font-weight: 700;
  line-height: 1;
}

/* 06. 按钮与标签 --------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 11px 22px;
  border: 1px solid transparent;
  border-radius: var(--radius-s);
  font-family: var(--font-sans);
  font-size: 15px;
  font-weight: 500;
  line-height: 1.2;
  cursor: pointer;
  text-align: center;
  transition: background-color 0.2s ease, border-color 0.2s ease,
    color 0.2s ease;
}

.btn--dark {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--bg);
}

.btn--dark:hover {
  background: var(--ink-soft);
  border-color: var(--ink-soft);
}

.btn--accent {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--white);
}

.btn--accent:hover {
  background: var(--accent-ink);
  border-color: var(--accent-ink);
}

.btn--ghost {
  background: transparent;
  border-color: var(--line-strong);
  color: var(--ink);
}

.btn--ghost:hover {
  background: var(--card-soft);
  border-color: var(--ink);
}

.btn--light {
  background: var(--bg);
  border-color: var(--muted);
  color: var(--ink);
}

.btn--light:hover {
  background: var(--white);
}

.btn--sm {
  min-height: 36px;
  padding: 8px 14px;
  font-size: 14px;
  border-radius: var(--radius-s);
}

.btn--block {
  width: 100%;
}

.btn__arrow {
  transition: transform 0.2s ease;
}

.btn:hover .btn__arrow {
  transform: translateX(4px);
}

.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border: 1px solid var(--line-strong);
  border-radius: 100px;
  font-size: 12px;
  line-height: 1.6;
  color: var(--meta);
  white-space: nowrap;
  align-self: flex-start;
}

.chip--accent {
  border-color: var(--accent);
  color: var(--accent-ink);
}

.chip--solid {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--bg);
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

/* 07. 卡片与深色容器 ----------------------------------------------------- */
.card {
  display: flex;
  flex-direction: column;
  background: var(--card);
  border-radius: var(--radius-xl);
  padding: 32px;
}

.card--soft {
  background: var(--card-soft);
}

.card--outline {
  background: transparent;
  border: 1px solid var(--line);
}

.card__top {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 20px;
}

.card h3 {
  font-size: 20px;
  margin-bottom: 12px;
}

.card p {
  font-size: 15px;
  line-height: 1.7;
  color: var(--ink-soft);
}

.card__foot {
  margin-top: auto;
  padding-top: 24px;
}

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

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

.card-grid--4 {
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.panel-dark {
  background: var(--ink);
  color: var(--bg);
  border-radius: var(--radius-xl);
  padding: 48px;
}

.panel-dark h2,
.panel-dark h3 {
  color: var(--bg);
}

.panel-dark p,
.panel-dark li {
  color: #d9d4c8;
}

.panel-dark .eyebrow {
  color: var(--muted);
}

.cta-panel {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr);
  gap: 48px;
  align-items: center;
  padding: 56px 48px;
}

.cta-panel h2 {
  font-family: var(--font-serif);
  font-size: clamp(26px, 3vw, 38px);
  line-height: 1.25;
  margin-bottom: 16px;
}

.cta-panel p {
  margin-bottom: 0;
}

.cta-panel__actions {
  display: flex;
  flex-direction: column;
  gap: 12px;
  align-items: stretch;
}

/* 08. 入口列表与筛选 ----------------------------------------------------- */
.filters {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 24px;
}

.filter-group {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-btn {
  min-height: 36px;
  padding: 6px 14px;
  border: 1px solid var(--line-strong);
  border-radius: 100px;
  background: transparent;
  color: var(--ink-soft);
  font-family: inherit;
  font-size: 13px;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease,
    border-color 0.2s ease;
}

.filter-btn:hover {
  border-color: var(--ink);
  color: var(--ink);
}

.filter-btn[aria-pressed="true"] {
  background: var(--ink);
  border-color: var(--ink);
  color: var(--bg);
}

.search-field {
  display: flex;
  align-items: center;
  gap: 8px;
  width: min(320px, 100%);
  padding: 6px 6px 6px 14px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-m);
  background: var(--white);
}

.search-field input {
  flex: 1;
  min-width: 0;
  padding: 6px 0;
  border: 0;
  background: transparent;
  font-family: inherit;
  font-size: 14px;
  color: var(--ink);
}

.search-field input:focus {
  outline: none;
}

.search-field:focus-within {
  border-color: var(--ink);
}

.search-field button {
  flex: none;
}

.mirror-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-strong);
  -webkit-user-select: none;
  user-select: none;
  -webkit-touch-callout: none;
}

.mirror-row {
  display: grid;
  grid-template-columns: 56px minmax(0, 1.05fr) 132px minmax(0, 1.2fr) auto;
  grid-template-areas: "idx domain type note action";
  gap: 24px;
  align-items: center;
  padding: 22px 12px;
  border-bottom: 1px solid var(--line);
  transition: background-color 0.2s ease;
}

.mirror-row:hover {
  background: #f4f1e8;
}

.mirror-row[hidden] {
  display: none;
}

.mirror-index {
  grid-area: idx;
  font-family: var(--font-serif);
  font-size: 18px;
  color: var(--meta);
  font-variant-numeric: tabular-nums;
}

.mirror-domain {
  grid-area: domain;
  min-width: 0;
}

.mirror-domain__name {
  display: block;
  font-family: var(--font-mono);
  font-size: 16px;
  font-weight: 500;
  line-height: 1.5;
  word-break: break-all;
}

.mirror-domain__full {
  display: block;
  margin-top: 2px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--meta);
  word-break: break-all;
}

.mirror-type {
  grid-area: type;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.mirror-note {
  grid-area: note;
  font-size: 14px;
  line-height: 1.65;
  color: var(--ink-soft);
  margin: 0;
}

.mirror-action {
  grid-area: action;
  display: flex;
  justify-content: flex-end;
}

.mirror-count {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: 20px;
  font-size: 13px;
  color: var(--meta);
}

.mirror-hint {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  margin-top: 16px;
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius-m);
  font-size: 13px;
  line-height: 1.65;
  color: var(--meta);
  background: var(--card-soft);
}

.mirror-hint::before {
  content: "i";
  flex: none;
  display: grid;
  place-items: center;
  width: 18px;
  height: 18px;
  margin-top: 1px;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  font-family: var(--font-serif);
  font-size: 11px;
  font-style: italic;
  color: var(--meta);
}

/* 09. 步骤 / 清单 / 双栏 ------------------------------------------------- */
.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
  counter-reset: step;
}

.step {
  position: relative;
  padding-top: 28px;
  border-top: 1px solid var(--ink);
  counter-increment: step;
}

.step::before {
  content: counter(step, decimal-leading-zero);
  display: block;
  margin-bottom: 16px;
  font-family: var(--font-serif);
  font-size: 32px;
  font-weight: 700;
  line-height: 1;
  color: var(--accent);
}

.step h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.step p {
  font-size: 15px;
  color: var(--ink-soft);
  margin-bottom: 0;
}

.split {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: 64px;
  align-items: start;
}

.checklist {
  list-style: none;
  margin: 0;
  padding: 0;
}

.checklist li {
  position: relative;
  padding: 16px 0 16px 40px;
  border-bottom: 1px solid var(--line);
  font-size: 15px;
  line-height: 1.7;
}

.checklist li:first-child {
  border-top: 1px solid var(--line);
}

.checklist li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 24px;
  width: 14px;
  height: 8px;
  border-left: 1.5px solid var(--accent-ink);
  border-bottom: 1.5px solid var(--accent-ink);
  transform: rotate(-45deg);
}

.checklist strong {
  display: block;
  margin-bottom: 2px;
}

.rules {
  list-style: none;
  margin: 0;
  padding: 0;
  counter-reset: rule;
}

.rules li {
  position: relative;
  padding: 20px 0 20px 56px;
  border-top: 1px solid rgba(250, 249, 245, 0.16);
  counter-increment: rule;
  font-size: 15px;
  line-height: 1.7;
}

.rules li:first-child {
  border-top: 0;
  padding-top: 0;
}

.rules li::before {
  content: "0" counter(rule);
  position: absolute;
  left: 0;
  top: 22px;
  font-family: var(--font-serif);
  font-size: 13px;
  color: var(--accent);
  letter-spacing: 0.08em;
}

.rules li:first-child::before {
  top: 2px;
}

.rules strong {
  display: block;
  color: var(--bg);
  margin-bottom: 2px;
  font-size: 16px;
}

.muted-note {
  font-size: 13px;
  color: var(--meta);
  line-height: 1.7;
}

/* 10. 时间线 / 表格 / 数据 ----------------------------------------------- */
.timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 24px;
  border-left: 1px solid var(--line-strong);
}

.timeline li {
  position: relative;
  padding: 0 0 32px 20px;
  margin: 0;
}

.timeline li:last-child {
  padding-bottom: 0;
}

.timeline li::before {
  content: "";
  position: absolute;
  left: -29px;
  top: 8px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--bg);
  border: 1px solid var(--ink);
}

.timeline time {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--meta);
  letter-spacing: 0.02em;
  margin-bottom: 4px;
}

.timeline h3 {
  font-size: 17px;
  margin-bottom: 4px;
}

.timeline p {
  font-size: 14px;
  line-height: 1.65;
  color: var(--ink-soft);
  margin: 0;
}

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius-m);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
  min-width: 560px;
}

.data-table caption {
  padding: 16px;
  text-align: left;
  font-size: 13px;
  color: var(--meta);
  border-bottom: 1px solid var(--line);
}

.data-table th,
.data-table td {
  padding: 14px 20px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
  line-height: 1.6;
}

.data-table thead th {
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.04em;
  color: var(--meta);
  background: var(--card-soft);
  white-space: nowrap;
}

.data-table tbody tr:last-child td {
  border-bottom: 0;
}

.data-table td:first-child {
  font-family: var(--font-mono);
  font-size: 13px;
  white-space: nowrap;
  color: var(--meta);
}

.stat-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0;
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}

.stat {
  padding: 32px 24px;
  border-left: 1px solid var(--line);
}

.stat:first-child {
  border-left: 0;
  padding-left: 0;
}

.stat .stat__num {
  font-family: var(--font-serif);
  font-size: clamp(32px, 3.4vw, 44px);
  font-weight: 700;
  line-height: 1;
  margin-bottom: 8px;
}

.stat .stat__num span {
  font-family: var(--font-sans);
  font-size: 13px;
  font-weight: 500;
  color: var(--meta);
  margin-left: 4px;
}

.stat p {
  font-size: 13px;
  color: var(--meta);
  line-height: 1.6;
  margin: 0;
}

/* 11. 常见问题折叠 ------------------------------------------------------- */
.faq-list {
  border-top: 1px solid var(--line-strong);
}

.faq-item {
  border-bottom: 1px solid var(--line);
}

.faq-item summary {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 24px;
  padding: 22px 4px;
  cursor: pointer;
  list-style: none;
  font-size: 17px;
  font-weight: 500;
  line-height: 1.55;
}

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

.faq-item summary::after {
  content: "+";
  flex: none;
  font-family: var(--font-serif);
  font-size: 20px;
  line-height: 1.4;
  color: var(--meta);
  transition: transform 0.2s ease;
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-item summary:hover {
  color: var(--accent-ink);
}

.faq-item__body {
  padding: 0 4px 24px;
  max-width: 78ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink-soft);
}

.faq-item__body p:last-child {
  margin-bottom: 0;
}

.faq-group {
  margin-bottom: 48px;
}

.faq-group h2 {
  font-size: 20px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--ink);
}

/* 12. 内页正文排版 ------------------------------------------------------- */
.page-hero {
  padding-top: 64px;
  padding-bottom: 40px;
}

.page-hero h1 {
  font-size: clamp(34px, 4.4vw, 56px);
  line-height: 1.14;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
  max-width: 20ch;
}

.page-hero .lead {
  margin-bottom: 24px;
}

.page-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 24px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  color: var(--meta);
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding-top: 24px;
  font-size: 12px;
  color: var(--meta);
}

.breadcrumb a {
  border-bottom: 1px solid transparent;
}

.breadcrumb a:hover {
  border-bottom-color: var(--meta);
}

.breadcrumb span[aria-hidden] {
  color: var(--line-strong);
}

.prose {
  max-width: 74ch;
}

.prose--wide {
  max-width: none;
}

.prose h2 {
  font-size: clamp(22px, 2.4vw, 28px);
  margin: 64px 0 16px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  scroll-margin-top: 96px;
}

.prose h2:first-child {
  margin-top: 0;
  border-top: 0;
  padding-top: 0;
}

.prose h3 {
  font-size: 19px;
  margin: 40px 0 12px;
  scroll-margin-top: 96px;
}

.prose p,
.prose li {
  font-size: 16px;
  line-height: 1.85;
  color: var(--ink-soft);
}

.prose p {
  margin-bottom: 20px;
}

.prose ul,
.prose ol {
  margin-bottom: 24px;
}

.prose li {
  margin-bottom: 10px;
}

.prose li strong {
  color: var(--ink);
}

.prose a:not(.btn) {
  border-bottom: 1px solid var(--line-strong);
  color: var(--ink);
  transition: border-color 0.2s ease, color 0.2s ease;
}

.prose a:not(.btn):hover {
  border-bottom-color: var(--accent);
  color: var(--accent-ink);
}

.prose blockquote {
  margin: 32px 0;
  padding: 4px 0 4px 24px;
  border-left: 2px solid var(--accent);
  font-family: var(--font-serif);
  font-size: 19px;
  line-height: 1.7;
  color: var(--ink);
}

.prose blockquote p {
  font-family: inherit;
  font-size: inherit;
  color: inherit;
  margin-bottom: 8px;
}

.prose code {
  padding: 2px 6px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: var(--card-soft);
  font-family: var(--font-mono);
  font-size: 0.9em;
}

.callout {
  margin: 32px 0;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-l);
  background: var(--card-soft);
}

.callout__title {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
  font-size: 14px;
  font-weight: 700;
}

.callout__title::before {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent);
}

.callout p,
.callout li {
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-soft);
}

.callout p:last-child {
  margin-bottom: 0;
}

.callout--warn {
  border-color: var(--accent);
  background: #f7ece6;
}

.toc {
  margin: 40px 0 0;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: var(--radius-l);
}

.toc h2 {
  margin: 0 0 12px;
  padding: 0;
  border: 0;
  font-size: 15px;
  letter-spacing: 0.04em;
  color: var(--meta);
}

.toc ol {
  columns: 2;
  column-gap: 32px;
  margin: 0;
  padding-left: 1.2em;
}

.toc li {
  font-size: 14px;
  line-height: 1.7;
  margin-bottom: 6px;
  break-inside: avoid;
}

.toc a {
  color: var(--ink-soft);
}

.toc a:hover {
  color: var(--ink);
  border-bottom-color: var(--ink);
}

.article-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 64px;
  align-items: start;
}

.aside-card {
  position: sticky;
  top: 104px;
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius-l);
  background: var(--card-soft);
}

.aside-card h2 {
  font-size: 16px;
  margin-bottom: 12px;
}

.aside-card p,
.aside-card li {
  font-size: 13px;
  line-height: 1.7;
  color: var(--meta);
}

.aside-card ul {
  margin: 0;
  padding-left: 1.1em;
}

.aside-card .btn {
  margin-top: 16px;
}

/* 跳转中间页 ------------------------------------------------------------- */
.leave-wrap {
  max-width: 880px;
  padding-bottom: 64px;
}

.leave-target {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  margin: 32px 0;
  padding: 24px 28px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-l);
}

.leave-target__label {
  display: block;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--meta);
  text-transform: uppercase;
  margin-bottom: 4px;
}

.leave-target__domain {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 500;
  word-break: break-all;
  -webkit-user-select: none;
  user-select: none;
}

.leave-target__url {
  display: block;
  margin-top: 4px;
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--meta);
  word-break: break-all;
  -webkit-user-select: none;
  user-select: none;
}

.leave-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 32px 0;
}

.leave-list {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  border-top: 1px solid var(--line-strong);
  -webkit-user-select: none;
  user-select: none;
}

.leave-list li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin: 0;
  padding: 14px 4px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}

.leave-list li.is-current {
  background: var(--card-soft);
}

.leave-list a {
  font-family: var(--font-mono);
  font-size: 14px;
  word-break: break-all;
}

.leave-list .leave-list__tag {
  flex: none;
}

/* 404 -------------------------------------------------------------------- */
.error-page {
  min-height: 62vh;
  display: flex;
  align-items: center;
  padding: 80px 0;
}

.error-code {
  font-family: var(--font-serif);
  font-size: clamp(72px, 14vw, 160px);
  line-height: 0.9;
  letter-spacing: -0.04em;
  margin-bottom: 24px;
}

.error-page h1 {
  font-size: clamp(28px, 3.6vw, 44px);
  margin-bottom: 16px;
}

/* 13. 页脚与广告位 ------------------------------------------------------- */
.ad-slot {
  margin: 0 auto;
  max-width: var(--shell);
  padding: 0 var(--pad);
}

.ad-slot:empty {
  display: none;
}

.ad-slot .ad-inner {
  margin: 48px 0 0;
  padding: 16px;
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius-m);
  text-align: center;
  font-size: 12px;
  color: var(--meta);
}

.site-footer {
  margin-top: 96px;
  background: var(--ink);
  color: var(--bg);
  border-radius: var(--radius-xl) var(--radius-xl) 0 0;
  padding: 64px 0 32px;
}

.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) repeat(3, minmax(0, 0.8fr));
  gap: 48px;
  padding-bottom: 48px;
  border-bottom: 1px solid rgba(250, 249, 245, 0.16);
}

.footer-brand__title {
  font-family: var(--font-serif);
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 12px;
}

.footer-brand p {
  font-size: 14px;
  line-height: 1.75;
  color: var(--muted);
  max-width: 36ch;
  margin-bottom: 16px;
}

.footer-brand .footer-domain {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--bg);
  letter-spacing: 0.02em;
}

.footer-col h2 {
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 16px;
}

.footer-col ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-col li {
  margin-bottom: 10px;
}

.footer-col a {
  font-size: 14px;
  color: #ded9cd;
  border-bottom: 1px solid transparent;
  transition: color 0.2s ease, border-color 0.2s ease;
}

.footer-col a:hover {
  color: var(--bg);
  border-bottom-color: var(--bg);
}

.footer-col p {
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
  margin-bottom: 12px;
}

.footer-bottom {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px 24px;
  padding-top: 24px;
  font-size: 12px;
  color: var(--muted);
}

.footer-bottom p {
  margin: 0;
}

.footer-bottom a {
  color: #ded9cd;
}

.footer-bottom a:hover {
  color: var(--bg);
}

/* 14. 工具类与响应式 ----------------------------------------------------- */
.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.no-select {
  -webkit-user-select: none;
  user-select: none;
}

.mt-0 { margin-top: 0 !important; }
.mt-16 { margin-top: 16px; }
.mt-24 { margin-top: 24px; }
.mt-32 { margin-top: 32px; }
.mt-48 { margin-top: 48px; }
.mb-0 { margin-bottom: 0 !important; }

.to-top {
  position: fixed;
  right: 24px;
  bottom: 24px;
  z-index: 90;
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border: 1px solid var(--line-strong);
  border-radius: 50%;
  background: var(--bg);
  color: var(--ink);
  font-size: 16px;
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(8px);
  transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s ease;
}

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

.to-top:hover {
  background: var(--card-soft);
}

@media (max-width: 1100px) {
  .hero-grid {
    gap: 40px;
  }

  .article-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 48px;
  }

  .aside-card {
    position: static;
  }

  .footer-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 40px;
  }
}

@media (max-width: 960px) {
  :root {
    --pad: 32px;
    --section-y: 72px;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 16px var(--pad) 24px;
    background: var(--bg);
    border-bottom: 1px solid var(--line);
  }

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

  .site-nav a:not(.btn) {
    padding: 12px 8px;
    border-bottom: 1px solid var(--line);
    border-radius: 0;
  }

  .site-nav a:not(.btn)::after {
    display: none;
  }

  .nav-cta {
    margin-left: 0;
    margin-top: 12px;
  }

  .hero {
    padding-top: 48px;
    padding-bottom: 56px;
  }

  .hero-grid,
  .split {
    grid-template-columns: minmax(0, 1fr);
    gap: 40px;
  }

  .card-grid,
  .card-grid--4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .steps {
    grid-template-columns: minmax(0, 1fr);
    gap: 32px;
  }

  .cta-panel {
    grid-template-columns: minmax(0, 1fr);
    gap: 32px;
    padding: 40px 32px;
  }

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

  .stat {
    border-left: 0;
    padding: 24px 0;
    border-top: 1px solid var(--line);
  }

  .stat:nth-child(-n + 2) {
    border-top: 0;
  }

  .stat:nth-child(even) {
    padding-left: 24px;
    border-left: 1px solid var(--line);
  }

  .mirror-row {
    grid-template-columns: 40px minmax(0, 1fr) auto;
    grid-template-areas:
      "idx domain action"
      ". type type"
      ". note note";
    gap: 8px 16px;
    padding: 20px 4px;
  }

  .mirror-action {
    justify-content: flex-end;
  }

  .mirror-note {
    font-size: 13px;
  }

  .toc ol {
    columns: 1;
  }
}

@media (max-width: 720px) {
  :root {
    --pad: 24px;
    --section-y: 56px;
  }

  body {
    font-size: 15px;
  }

  .section-head {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
    margin-bottom: 32px;
  }

  .hero-title {
    font-size: clamp(34px, 9vw, 48px);
  }

  .hero-lead,
  .lead {
    font-size: 16px;
  }

  .hero-actions .btn {
    flex: 1 1 auto;
  }

  .hero-stats {
    gap: 16px;
  }

  .hero-stats dt {
    font-size: 24px;
  }

  .card-grid,
  .card-grid--2,
  .card-grid--4 {
    grid-template-columns: minmax(0, 1fr);
  }

  .panel-dark {
    padding: 32px 24px;
  }

  .card {
    padding: 24px;
  }

  .filters {
    align-items: stretch;
  }

  .search-field {
    width: 100%;
  }

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

  .site-footer {
    margin-top: 64px;
    padding-top: 48px;
  }

  .page-hero {
    padding-top: 40px;
  }

  .data-table {
    min-width: 0;
  }

  .data-table th,
  .data-table td {
    padding: 12px 14px;
  }

  .data-table td:first-child {
    white-space: nowrap;
  }

  .prose h2 {
    margin-top: 48px;
  }

  .leave-target {
    padding: 20px;
  }

  .leave-actions .btn {
    flex: 1 1 100%;
  }

  .to-top {
    right: 16px;
    bottom: 16px;
  }
}

/* 15. 动效与打印 --------------------------------------------------------- */
@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;
  }
}

@media print {
  .site-header,
  .site-footer,
  .to-top,
  .ad-slot,
  .filters {
    display: none !important;
  }

  body {
    background: #fff;
    color: #000;
  }

  a {
    text-decoration: underline;
  }
}