/* ============================================================
   91黑料网 · 整站样式表
   版本: 1.0.0
   说明: 本文件为 cdfmd.com 全站唯一样式表，覆盖首页、全部内页与 404 页。
   分组: base / layout / components / pages / responsive
   ============================================================ */

/* ============================================================
   Base — 全局基础
   ============================================================ */
:root {
  --color-bg: #f7f8fa;
  --color-surface: #ffffff;
  --color-text: #1f2937;
  --color-text-secondary: #374151;
  --color-primary: #0f766e;
  --color-primary-dark: #115e59;
  --color-accent: #ea580c;
  --color-border: #64748b;
  --color-border-light: #e5e7eb;
  --color-muted: #6b7280;
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.06);
  --shadow-md: 0 4px 12px rgba(15, 23, 42, 0.08);
  --shadow-lg: 0 8px 24px rgba(15, 23, 42, 0.1);
  --container-width: 1200px;
  --header-height: 64px;
  --font-family: "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: 15px;
  line-height: 1.7;
  color: var(--color-text);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: var(--color-primary-dark);
}

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  font-weight: 700;
  line-height: 1.35;
  color: var(--color-text);
}

h1 {
  font-size: 28px;
}

h2 {
  font-size: 22px;
}

h3 {
  font-size: 17px;
}

h4 {
  font-size: 15px;
}

p {
  margin-bottom: 12px;
}

time {
  font-size: 13px;
  color: var(--color-muted);
}

button {
  font-family: inherit;
  font-size: inherit;
  border: none;
  background: none;
  cursor: pointer;
}

/* ============================================================
   Layout — 全站骨架与容器
   ============================================================ */

/* 全站统一容器宽度 */
.header-shell,
.site-main,
.footer-shell {
  width: 100%;
  max-width: var(--container-width);
  margin: 0 auto;
  padding-left: 24px;
  padding-right: 24px;
}

/* --- 页头 --- */
.site-header {
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border-light);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-shell {
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  flex-shrink: 0;
}

.brand-name {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-primary);
  letter-spacing: 0.5px;
}

.brand-tagline {
  font-size: 13px;
  color: var(--color-muted);
  white-space: nowrap;
}

/* --- 导航 --- */
.site-nav {
  display: block;
}

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

.nav-list li a {
  display: block;
  padding: 8px 14px;
  font-size: 15px;
  font-weight: 500;
  color: var(--color-text-secondary);
  border-radius: var(--radius-sm);
  transition: color 0.2s ease, background-color 0.2s ease;
}

.nav-list li a:hover {
  color: var(--color-primary);
  background-color: rgba(15, 118, 110, 0.06);
}

.nav-list li a.is-current {
  color: var(--color-primary);
  font-weight: 700;
  background-color: rgba(15, 118, 110, 0.1);
}

/* 移动端汉堡按钮 — 默认隐藏，手机显示 */
.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  background-color: var(--color-surface);
  color: var(--color-text);
  font-size: 14px;
  font-weight: 500;
  min-height: 44px;
  cursor: pointer;
}

.nav-toggle-icon {
  width: 18px;
  height: 14px;
  position: relative;
  display: block;
}

.nav-toggle-icon::before,
.nav-toggle-icon::after {
  content: "";
  position: absolute;
  left: 0;
  width: 100%;
  height: 2px;
  background-color: var(--color-text);
  transition: transform 0.25s ease, top 0.25s ease;
}

.nav-toggle-icon::before {
  top: 0;
}

.nav-toggle-icon::after {
  top: 12px;
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon::before {
  top: 6px;
  transform: rotate(45deg);
}

.nav-toggle[aria-expanded="true"] .nav-toggle-icon::after {
  top: 6px;
  transform: rotate(-45deg);
}

.nav-toggle-text {
  font-size: 14px;
}

/* --- 页脚 --- */
.site-footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border-light);
  margin-top: 64px;
}

.footer-shell {
  padding-top: 40px;
  padding-bottom: 24px;
}

.footer-brand {
  margin-bottom: 32px;
}

.footer-brand p {
  font-size: 14px;
  color: var(--color-text-secondary);
  max-width: 420px;
  margin-bottom: 0;
}

.footer-links {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--color-border-light);
}

.footer-col h4 {
  font-size: 14px;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--color-text);
}

.footer-col a {
  display: block;
  font-size: 14px;
  color: var(--color-text-secondary);
  padding: 4px 0;
}

.footer-col a:hover {
  color: var(--color-primary);
}

.footer-bottom {
  padding-top: 20px;
  text-align: center;
}

.footer-bottom span {
  font-size: 13px;
  color: var(--color-muted);
}

/* --- 面包屑 --- */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 0 8px;
  font-size: 13px;
  color: var(--color-muted);
}

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

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

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

.breadcrumb-current {
  color: var(--color-text);
  font-weight: 500;
}

/* --- 页面标题区（内页统一） --- */
.page-header {
  padding: 24px 0 28px;
}

.page-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 10px;
}

.page-description {
  font-size: 15px;
  color: var(--color-text-secondary);
  max-width: 720px;
  line-height: 1.7;
}

/* --- 主内容 --- */
.site-main {
  padding-top: 8px;
  padding-bottom: 48px;
}

/* 内页统一容器 */
.layout-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 32px;
  align-items: start;
}

.layout-shell.sidebar-right {
  grid-template-columns: minmax(0, 1fr) 300px;
}

.layout-shell.sidebar-left {
  grid-template-columns: 300px minmax(0, 1fr);
}

.main-col {
  min-width: 0;
  min-height: 200px;
}

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

/* 通用 section 标题 */
.section-title {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

/* ============================================================
   Components — 通用组件
   ============================================================ */

/* --- 按钮 --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 22px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-md);
  min-height: 44px;
  transition: background-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}

.btn-primary {
  background-color: var(--color-primary);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  color: #ffffff;
}

.btn-secondary {
  background-color: transparent;
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
}

.btn-secondary:hover {
  background-color: rgba(15, 118, 110, 0.08);
}

.btn-outline {
  background-color: transparent;
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
  padding: 8px 18px;
  min-height: 40px;
}

.btn-outline:hover {
  background-color: rgba(15, 118, 110, 0.08);
}

/* --- 状态标签 --- */
.status-tag,
.tag {
  display: inline-block;
  padding: 2px 10px;
  font-size: 12px;
  font-weight: 600;
  border-radius: 999px;
  line-height: 1.6;
  white-space: nowrap;
}

.status-view,
.tag-view {
  background-color: rgba(15, 118, 110, 0.1);
  color: var(--color-primary);
}

.status-reply,
.tag-reply {
  background-color: rgba(234, 88, 12, 0.1);
  color: var(--color-accent);
}

/* --- 版块卡片（首页网格版） --- */
.board-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.board-card {
  display: flex;
  flex-direction: column;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: box-shadow 0.25s ease, border-color 0.25s ease, transform 0.25s ease;
}

.board-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
  transform: translateY(-2px);
}

.board-card img {
  width: 100%;
  height: 140px;
  object-fit: cover;
}

.board-card h3 {
  padding: 14px 16px 4px;
  font-size: 16px;
}

.board-card p {
  padding: 0 16px;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  flex-grow: 1;
}

.audience-tag {
  display: inline-block;
  margin: 8px 16px 4px;
  font-size: 12px;
  color: var(--color-primary);
  background-color: rgba(15, 118, 110, 0.08);
  padding: 3px 10px;
  border-radius: 999px;
}

.board-meta {
  display: block;
  padding: 0 16px 14px;
  font-size: 13px;
  color: var(--color-muted);
}

/* --- 话题列表（首页） --- */
.thread-list {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.thread-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--color-border-light);
  transition: background-color 0.2s ease;
}

.thread-item:last-child {
  border-bottom: none;
}

.thread-item:hover {
  background-color: rgba(15, 118, 110, 0.03);
}

.thread-title {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  flex: 0 1 auto;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.thread-title a {
  color: inherit;
}

.thread-title a:hover {
  color: var(--color-primary);
}

.thread-board {
  font-size: 13px;
  color: var(--color-muted);
  flex-shrink: 0;
}

.thread-time {
  margin-left: auto;
  flex-shrink: 0;
}

/* --- 首页双卡（规则+指南） --- */
.dual-card {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 48px;
}

.card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 28px;
}

.card h2 {
  font-size: 18px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

.card ul {
  margin-bottom: 20px;
}

.card ul li {
  padding: 8px 0 8px 20px;
  position: relative;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.card ul li::before {
  content: "";
  position: absolute;
  left: 4px;
  top: 16px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--color-primary);
}

/* 步骤列表 */
.step-list {
  counter-reset: step;
  margin-bottom: 24px;
}

.step-list li {
  counter-increment: step;
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 10px 0;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.step-list li::before {
  content: counter(step);
  flex-shrink: 0;
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background-color: var(--color-primary);
  color: #fff;
  font-size: 13px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-top: 2px;
}

/* --- 侧栏（首页） --- */
.side-column {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
}

.side-title {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

.notice-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--color-border-light);
}

.notice-list li:last-child {
  border-bottom: none;
}

.notice-list a {
  display: block;
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 4px;
  line-height: 1.5;
}

.notice-list a:hover {
  color: var(--color-primary);
}

.notice-date {
  font-size: 12px;
  color: var(--color-muted);
}

.side-link {
  display: inline-block;
  margin-top: 16px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
}

.side-link:hover {
  color: var(--color-primary-dark);
}

/* --- 最新动态摘要条 --- */
.update-strip {
  margin-top: 48px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 24px 28px;
}

.update-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 16px;
}

.update-item {
  padding: 12px;
  background-color: var(--color-bg);
  border-radius: var(--radius-md);
}

.update-item time {
  display: block;
  font-size: 12px;
  color: var(--color-muted);
  margin-bottom: 6px;
}

.update-item span {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.link-more {
  display: inline-block;
  margin-top: 16px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
}

.link-more:hover {
  color: var(--color-primary-dark);
}

/* --- 帮助反馈入口（首页） --- */
.help-entry {
  margin-top: 48px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 32px;
  text-align: center;
}

.help-entry h2 {
  font-size: 20px;
  margin-bottom: 12px;
}

.help-entry p {
  font-size: 14px;
  color: var(--color-text-secondary);
  max-width: 560px;
  margin: 0 auto 20px;
}

.help-categories {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 24px;
}

.help-categories span {
  display: inline-block;
  padding: 6px 16px;
  font-size: 13px;
  color: var(--color-text-secondary);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: 999px;
}

/* --- 公告条 --- */
.notice-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  background-color: rgba(15, 118, 110, 0.06);
  border: 1px solid rgba(15, 118, 110, 0.15);
  border-radius: var(--radius-md);
  padding: 10px 16px;
  margin-top: 24px;
  margin-bottom: 32px;
}

.notice-label {
  flex-shrink: 0;
  font-size: 13px;
  font-weight: 700;
  color: var(--color-primary);
  background-color: var(--color-primary);
  color: #fff;
  padding: 2px 10px;
  border-radius: 999px;
}

.notice-link {
  font-size: 14px;
  color: var(--color-text);
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.notice-link:hover {
  color: var(--color-primary);
}

.notice-time {
  flex-shrink: 0;
  font-size: 12px;
}

/* ============================================================
   Pages — 首页
   ============================================================ */

/* --- Hero 区 --- */
.hero-section {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 40px;
  align-items: center;
  padding: 48px 0 8px;
}

.hero-copy h1 {
  font-size: 32px;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 16px;
  color: var(--color-text);
}

.hero-lead {
  font-size: 16px;
  color: var(--color-text-secondary);
  line-height: 1.8;
  margin-bottom: 24px;
  max-width: 520px;
}

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

.hero-media img {
  width: 100%;
  height: 280px;
  object-fit: cover;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

/* --- 首页双栏布局 --- */
.home-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 32px;
  margin-top: 24px;
  align-items: start;
}

.main-column {
  min-width: 0;
}

/* --- 热帖区 --- */
.hot-threads {
  margin-top: 48px;
}

/* --- 首页版块卡片配图统一高度 --- */
.board-grid .board-card img {
  height: 130px;
}

/* ============================================================
   Pages — 版块目录 boards.html
   ============================================================ */

.board-list-section .board-card {
  flex-direction: row;
  padding: 20px;
  margin-bottom: 20px;
  overflow: hidden;
}

.board-list-section .board-media {
  flex-shrink: 0;
  width: 200px;
}

.board-list-section .board-media img {
  width: 100%;
  height: 140px;
  object-fit: cover;
  border-radius: var(--radius-md);
}

.board-list-section .board-content {
  flex: 1;
  min-width: 0;
  padding-left: 20px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.board-list-section .board-content h3 {
  font-size: 18px;
  padding: 0;
}

.board-list-section .board-content p {
  padding: 0;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
}

.board-list-section .board-audience {
  font-size: 13px;
  color: var(--color-primary);
  background-color: rgba(15, 118, 110, 0.08);
  padding: 3px 10px;
  border-radius: 999px;
  display: inline-block;
  align-self: flex-start;
  margin: 4px 0;
}

.board-list-section .board-boundary {
  font-size: 13px;
  color: var(--color-muted);
  border-left: 3px solid var(--color-border-light);
  padding-left: 10px;
  margin: 4px 0;
}

.board-link {
  display: inline-block;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  margin-top: 6px;
  align-self: flex-start;
}

.board-link:hover {
  color: var(--color-primary-dark);
}

/* --- 侧栏标签 --- */
.tag-sidebar {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
}

.tag-sidebar h2 {
  font-size: 17px;
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

.tag-list li {
  padding: 10px 0;
  border-bottom: 1px solid var(--color-border-light);
}

.tag-list li:last-child {
  border-bottom: none;
}

.tag-list a {
  display: block;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 2px;
}

.tag-list a:hover {
  color: var(--color-primary);
}

.tag-list span {
  font-size: 13px;
  color: var(--color-muted);
  line-height: 1.5;
  display: block;
}

/* ============================================================
   Pages — 讨论广场 threads.html
   ============================================================ */

/* 状态标签条 */
.status-tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 24px;
}

.status-tab {
  display: inline-block;
  padding: 8px 20px;
  font-size: 14px;
  font-weight: 500;
  color: var(--color-text-secondary);
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: 999px;
  cursor: pointer;
  transition: background-color 0.2s ease, color 0.2s ease, border-color 0.2s ease;
}

.status-tab:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
}

.status-tab.is-active {
  background-color: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* 话题列表 */
.thread-list-section {
  margin-top: 8px;
}

.thread-list-section .thread-list {
  display: flex;
  flex-direction: column;
}

.thread-list-section .thread-item {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  padding: 18px 20px;
}

.thread-thumb {
  width: 96px;
  height: 68px;
  object-fit: cover;
  border-radius: var(--radius-sm);
  flex-shrink: 0;
}

.thread-content {
  flex: 1;
  min-width: 0;
}

.thread-content .thread-title {
  font-size: 16px;
  margin-bottom: 6px;
  white-space: normal;
  overflow: visible;
}

.thread-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 6px;
  flex-wrap: wrap;
}

.thread-meta .thread-board {
  font-size: 13px;
}

.thread-summary {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 4px;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.thread-content .thread-time {
  font-size: 12px;
  color: var(--color-muted);
  margin-left: 0;
}

/* 热帖置顶区 */
.hot-threads-section {
  margin-top: 48px;
}

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

.hot-thread-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
  transition: box-shadow 0.25s ease, border-color 0.25s ease;
}

.hot-thread-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-accent);
}

.hot-thread-title {
  font-size: 15px;
  line-height: 1.5;
  margin-bottom: 12px;
}

.hot-thread-title a {
  color: var(--color-text);
}

.hot-thread-title a:hover {
  color: var(--color-primary);
}

.hot-thread-meta {
  display: flex;
  align-items: center;
  gap: 10px;
}

.hot-thread-board {
  font-size: 13px;
  color: var(--color-muted);
}

/* 相关链接 */
.thread-related-links {
  margin-top: 40px;
  padding: 20px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
}

.thread-related-links p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 0;
}

.thread-related-links a {
  font-weight: 600;
  margin: 0 6px;
}

/* ============================================================
   Pages — 新手指南 guide.html
   ============================================================ */

/* 步骤区 */
.guide-steps {
  margin-bottom: 48px;
}

.steps-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.step-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: box-shadow 0.25s ease, border-color 0.25s ease;
}

.step-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.step-card-media img {
  width: 100%;
  height: 96px;
  object-fit: cover;
}

.step-card-body {
  padding: 16px;
}

.step-index {
  display: inline-block;
  font-size: 13px;
  font-weight: 700;
  color: var(--color-primary);
  background-color: rgba(15, 118, 110, 0.1);
  padding: 2px 10px;
  border-radius: 999px;
  margin-bottom: 10px;
}

.step-card-body h3 {
  font-size: 15px;
  margin-bottom: 6px;
}

.step-card-body p {
  font-size: 13px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 规则卡片 */
.guide-rules {
  margin-bottom: 48px;
}

.rules-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}

.rule-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  padding: 20px 16px;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.rule-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

.rule-card h3 {
  font-size: 15px;
  margin-bottom: 8px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

.rule-card p {
  font-size: 13px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 0;
}

/* 发言规范与举报说明 */
.guide-policy {
  margin-bottom: 48px;
}

.policy-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
}

.policy-block {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
}

.policy-block h3 {
  font-size: 16px;
  margin-bottom: 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--color-primary);
  display: inline-block;
}

.policy-block p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* 相关入口 */
.guide-links {
  margin-top: 8px;
}

.guide-links-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 24px;
  text-align: center;
}

.guide-links-card h3 {
  font-size: 16px;
  margin-bottom: 8px;
}

.guide-links-card p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 0;
}

.guide-links-card a {
  font-weight: 600;
  margin: 0 8px;
}

/* ============================================================
   Pages — 发展记录 records.html
   ============================================================ */

/* 时间线 */
.timeline-section {
  margin-bottom: 48px;
}

.timeline-list {
  position: relative;
  padding-left: 32px;
}

.timeline-list::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 2px;
  background-color: var(--color-border-light);
}

.timeline-item {
  position: relative;
  margin-bottom: 32px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 20px;
}

.timeline-marker {
  position: absolute;
  left: -30px;
  top: 24px;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background-color: var(--color-primary);
  border: 3px solid var(--color-surface);
  box-shadow: 0 0 0 2px var(--color-primary);
}

.timeline-marker time {
  position: absolute;
  left: 28px;
  top: -2px;
  font-size: 13px;
  font-weight: 700;
  color: var(--color-primary);
  white-space: nowrap;
}

.timeline-content img {
  width: 100%;
  height: 120px;
  object-fit: cover;
  border-radius: var(--radius-md);
  margin-bottom: 12px;
}

.timeline-content h3 {
  font-size: 16px;
  margin-bottom: 8px;
}

.timeline-content p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 0;
}

/* 节点背景说明 */
.background-notes {
  margin-bottom: 48px;
}

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

.note-item {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  padding: 20px;
}

.note-item h3 {
  font-size: 15px;
  margin-bottom: 8px;
}

.note-item p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 0;
}

/* 后续计划 */
.future-plans {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 28px;
  margin-bottom: 32px;
}

.future-plans h2 {
  font-size: 18px;
  margin-bottom: 12px;
}

.future-plans p {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* 相关导航 */
.related-links {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  padding: 20px;
}

.related-links p {
  font-size: 14px;
  color: var(--color-text-secondary);
  margin-bottom: 0;
}

.related-links a {
  font-weight: 600;
  margin: 0 8px;
}

/* ============================================================
   Pages — 帮助反馈 help.html
   ============================================================ */

/* 帮助分类概览 */
.help-categories {
  margin-bottom: 48px;
}

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

.category-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: box-shadow 0.25s ease, border-color 0.25s ease;
}

.category-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-primary);
}

.category-card img {
  width: 100%;
  height: 130px;
  object-fit: cover;
}

.category-card h3 {
  font-size: 16px;
  padding: 16px 16px 4px;
}

.category-card p {
  font-size: 14px;
  color: var(--color-text-secondary);
  padding: 0 16px;
  line-height: 1.6;
  flex-grow: 1;
}

.category-card a {
  display: inline-block;
  margin: 8px 16px 16px;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
}

.category-card a:hover {
  color: var(--color-primary-dark);
}

/* FAQ 折叠区 */
.faq-section {
  margin-bottom: 48px;
}

.faq-list {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

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

.faq-item:last-child {
  border-bottom: none;
}

.faq-item summary {
  padding: 18px 24px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  position: relative;
  padding-right: 48px;
  transition: background-color 0.2s ease;
  list-style: none;
}

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

.faq-item summary::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 22px;
  font-weight: 400;
  color: var(--color-primary);
  transition: transform 0.25s ease;
}

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

.faq-item summary:hover {
  background-color: rgba(15, 118, 110, 0.04);
}

.faq-item p {
  padding: 0 24px 18px;
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.7;
  margin-bottom: 0;
}

.faq-item p a {
  font-weight: 600;
}

/* 反馈流程 */
.feedback-process {
  margin-bottom: 48px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.process-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  margin-top: 20px;
}

.step-item {
  text-align: center;
  padding: 16px;
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background-color: var(--color-primary);
  color: #fff;
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 12px;
}

.step-title {
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 6px;
  color: var(--color-text);
}

.step-item p {
  font-size: 13px;
  color: var(--color-text-secondary);
  line-height: 1.6;
  margin-bottom: 0;
}

.process-note {
  margin-top: 24px;
  padding: 16px;
  background-color: var(--color-bg);
  border-radius: var(--radius-md);
  font-size: 14px;
  color: var(--color-text-secondary);
  text-align: center;
  margin-bottom: 0;
}

/* 相关入口 */
.related-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.related-grid a {
  display: block;
  padding: 16px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  text-align: center;
  transition: border-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
}

.related-grid a:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  box-shadow: var(--shadow-sm);
}

/* ============================================================
   Pages — 404 页
   ============================================================ */

.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: calc(100vh - var(--header-height) - 220px);
  padding-top: 48px;
  padding-bottom: 48px;
}

.error-panel {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 48px 40px;
  text-align: center;
  max-width: 560px;
  width: 100%;
}

.error-code {
  font-size: 64px;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1;
  margin-bottom: 16px;
}

.error-panel h1 {
  font-size: 24px;
  margin-bottom: 12px;
}

.error-desc {
  font-size: 15px;
  color: var(--color-text-secondary);
  margin-bottom: 28px;
}

.error-actions {
  display: flex;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
}

.error-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 24px;
  background-color: var(--color-primary);
  color: #fff;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-md);
  min-height: 44px;
}

.error-btn:hover {
  background-color: var(--color-primary-dark);
  color: #fff;
}

.error-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 24px;
  border: 1px solid var(--color-primary);
  color: var(--color-primary);
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius-md);
  min-height: 44px;
}

.error-link:hover {
  background-color: rgba(15, 118, 110, 0.08);
}

/* ============================================================
   Responsive — 响应式断点
   ============================================================ */

/* --- 992px 平板 --- */
@media (max-width: 992px) {
  .header-shell,
  .site-main,
  .footer-shell {
    padding-left: 20px;
    padding-right: 20px;
  }

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

  .home-layout {
    grid-template-columns: 1fr;
  }

  .side-column {
    margin-top: 0;
  }

  .layout-shell,
  .layout-shell.sidebar-right,
  .layout-shell.sidebar-left {
    grid-template-columns: 1fr;
  }

  .side-col {
    order: 2;
  }

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

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

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

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

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

  .update-list {
    grid-template-columns: 1fr;
  }

  .hero-section {
    grid-template-columns: 1fr;
    gap: 24px;
    padding-top: 32px;
  }

  .hero-media img {
    height: 220px;
  }

  .board-list-section .board-card {
    flex-direction: column;
  }

  .board-list-section .board-media {
    width: 100%;
  }

  .board-list-section .board-media img {
    height: 160px;
  }

  .board-list-section .board-content {
    padding-left: 0;
    padding-top: 16px;
  }
}

/* --- 768px 手机横屏/小平板 --- */
@media (max-width: 768px) {
  :root {
    --header-height: 56px;
  }

  .header-shell {
    height: var(--header-height);
  }

  .brand-tagline {
    display: none;
  }

  .brand-name {
    font-size: 20px;
  }

  h1 {
    font-size: 24px;
  }

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

  .hero-copy h1 {
    font-size: 26px;
  }

  .dual-card {
    grid-template-columns: 1fr;
  }

  .policy-grid {
    grid-template-columns: 1fr;
  }

  .process-steps {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .notes-grid {
    grid-template-columns: 1fr;
  }

  .timeline-list {
    padding-left: 24px;
  }

  .timeline-marker {
    left: -24px;
    width: 16px;
    height: 16px;
  }

  .timeline-marker time {
    left: 24px;
    font-size: 12px;
  }

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

  .board-grid {
    grid-template-columns: 1fr;
  }

  .steps-grid {
    grid-template-columns: 1fr;
  }

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

  .hot-thread-grid {
    grid-template-columns: 1fr;
  }

  .category-grid {
    grid-template-columns: 1fr;
  }

  .thread-list-section .thread-item {
    flex-direction: column;
  }

  .thread-thumb {
    width: 100%;
    height: 140px;
  }

  .thread-item {
    flex-wrap: wrap;
    gap: 8px;
  }

  .thread-title {
    width: 100%;
    white-space: normal;
  }

  .thread-time {
    margin-left: 0;
  }

  .notice-bar {
    flex-wrap: wrap;
  }

  .notice-link {
    width: 100%;
    white-space: normal;
  }
}

/* --- 576px 手机竖屏 --- */
@media (max-width: 576px) {
  .header-shell,
  .site-main,
  .footer-shell {
    padding-left: 16px;
    padding-right: 16px;
  }

  /* 移动导航：显示汉堡按钮，隐藏列表 */
  .nav-toggle {
    display: inline-flex;
  }

  .site-nav {
    position: absolute;
    top: var(--header-height);
    left: 0;
    right: 0;
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border-light);
    box-shadow: var(--shadow-md);
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    padding: 8px 16px 16px;
    gap: 0;
  }

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

  .nav-list li a {
    padding: 12px 12px;
    font-size: 15px;
    border-radius: var(--radius-sm);
  }

  .page-header {
    padding: 16px 0 20px;
  }

  .page-title {
    font-size: 22px;
  }

  .page-description {
    font-size: 14px;
  }

  .hero-section {
    padding-top: 24px;
  }

  .hero-copy h1 {
    font-size: 24px;
    line-height: 1.35;
  }

  .hero-lead {
    font-size: 15px;
  }

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

  .hero-actions .btn {
    width: 100%;
  }

  .hero-media img {
    height: 180px;
  }

  .board-card img {
    height: 120px;
  }

  .rules-grid {
    grid-template-columns: 1fr;
  }

  .related-grid {
    grid-template-columns: 1fr;
  }

  .footer-links {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .footer-brand {
    margin-bottom: 24px;
  }

  .footer-col h4 {
    margin-bottom: 8px;
  }

  .footer-col a {
    padding: 3px 0;
  }

  .breadcrumb {
    padding-top: 12px;
    font-size: 12px;
    flex-wrap: wrap;
  }

  .update-list {
    gap: 16px;
  }

  .update-item {
    padding: 10px;
  }

  .help-entry {
    padding: 24px 16px;
  }

  .help-categories {
    gap: 8px;
  }

  .help-categories span {
    font-size: 12px;
    padding: 5px 12px;
  }

  .dual-card {
    gap: 16px;
    margin-top: 32px;
  }

  .card {
    padding: 20px;
  }

  .hot-threads {
    margin-top: 32px;
  }

  .update-strip {
    margin-top: 32px;
    padding: 20px;
  }

  .help-entry {
    margin-top: 32px;
  }

  .error-panel {
    padding: 32px 20px;
  }

  .error-code {
    font-size: 48px;
  }

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

  .error-btn,
  .error-link {
    width: 100%;
  }

  .status-tabs {
    gap: 8px;
  }

  .status-tab {
    padding: 6px 14px;
    font-size: 13px;
  }

  .thread-list-section .thread-item {
    padding: 14px;
  }

  .thread-thumb {
    height: 120px;
  }

  .hot-thread-card {
    padding: 16px;
  }

  .faq-item summary {
    padding: 14px 40px 14px 16px;
    font-size: 14px;
  }

  .faq-item p {
    padding: 0 16px 14px;
  }

  .feedback-process {
    padding: 24px 16px;
  }

  .process-steps {
    gap: 8px;
  }

  .step-item {
    padding: 12px 8px;
  }

  .timeline-item {
    padding: 16px;
  }

  .timeline-content img {
    height: 100px;
  }

  .policy-block {
    padding: 20px 16px;
  }
}

/* --- 400px 小屏手机 --- */
@media (max-width: 400px) {
  .header-shell {
    gap: 12px;
  }

  .nav-toggle {
    padding: 8px 10px;
  }

  .nav-toggle-text {
    font-size: 13px;
  }

  .brand-name {
    font-size: 18px;
  }

  .board-grid {
    gap: 16px;
  }

  .board-card img {
    height: 110px;
  }

  .thread-item {
    padding: 12px 14px;
  }

  .status-tag,
  .tag {
    padding: 1px 8px;
    font-size: 11px;
  }

  .notice-bar {
    padding: 8px 12px;
  }

  .notice-label {
    font-size: 12px;
  }
}

/* ============================================================
   可访问性与焦点样式
   ============================================================ */

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

a:focus-visible,
button:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* 整卡可点击时保留焦点 */
a.board-card:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* 减少动效偏好 */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}