/* ==========================================================================
   base
   ========================================================================== */

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

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: #2c3e50;
  background-color: #f5f7fa;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

a {
  color: #1a73e8;
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: #1557b0;
}

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4,
h5,
h6 {
  line-height: 1.3;
  font-weight: 700;
  color: #2c3e50;
}

/* ==========================================================================
   layout
   ========================================================================== */

.site-body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.site-main {
  flex: 1 0 auto;
  width: 100%;
}

.site-header {
  background-color: #ffffff;
  border-bottom: 1px solid #e5e9f0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand {
  display: flex;
  align-items: center;
  flex-shrink: 0;
  font-size: 20px;
  font-weight: 700;
  color: #1a73e8;
}

.brand:hover {
  color: #1a73e8;
}

.brand-name {
  letter-spacing: 0.02em;
}

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

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

.nav-list li {
  margin: 0;
}

.nav-list a {
  display: block;
  padding: 8px 14px;
  font-size: 15px;
  font-weight: 500;
  color: #5a6b7d;
  border-radius: 6px;
  transition: background-color 0.2s ease, color 0.2s ease;
}

.nav-list a:hover {
  background-color: #e8f0fe;
  color: #1a73e8;
}

.nav-list a.is-current {
  background-color: #e8f0fe;
  color: #1a73e8;
  font-weight: 600;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 44px;
  height: 44px;
  padding: 10px;
  background: transparent;
  border: none;
  cursor: pointer;
  gap: 5px;
}

.nav-toggle-bar {
  display: block;
  width: 22px;
  height: 2px;
  background-color: #2c3e50;
  border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.site-footer {
  background-color: #2c3e50;
  color: #b0bec5;
  margin-top: auto;
}

.footer-columns {
  max-width: 1200px;
  margin: 0 auto;
  padding: 48px 24px 32px;
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
}

.footer-col h3 {
  color: #ffffff;
  font-size: 16px;
  margin-bottom: 16px;
}

.footer-brand {
  font-size: 20px;
  font-weight: 700;
  color: #ffffff;
  margin-bottom: 8px;
}

.footer-desc {
  font-size: 14px;
  line-height: 1.7;
  max-width: 360px;
}

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

.footer-links a {
  color: #b0bec5;
  font-size: 14px;
  transition: color 0.2s ease;
}

.footer-links a:hover {
  color: #ffffff;
}

.footer-text {
  font-size: 14px;
  margin-bottom: 12px;
  line-height: 1.7;
}

.footer-link {
  display: inline-block;
  color: #90caf9;
  font-size: 14px;
  font-weight: 500;
}

.footer-link:hover {
  color: #ffffff;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding: 20px 24px;
  text-align: center;
}

.footer-bottom p {
  font-size: 13px;
  color: #78909c;
}

/* ==========================================================================
   components
   ========================================================================== */

/* ---------- 面包屑 ---------- */

.breadcrumb {
  max-width: 1200px;
  margin: 0 auto;
  padding: 20px 24px 0;
  font-size: 14px;
  color: #78909c;
}

.breadcrumb a {
  color: #1a73e8;
}

.breadcrumb a:hover {
  color: #1557b0;
  text-decoration: underline;
}

.breadcrumb-sep {
  margin: 0 8px;
  color: #b0bec5;
}

.breadcrumb-current {
  color: #546e7a;
}

/* ---------- 页面标题区 ---------- */

.page-header {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px 24px 8px;
}

.page-title {
  font-size: 32px;
  font-weight: 700;
  color: #2c3e50;
  margin-bottom: 8px;
}

.page-description {
  font-size: 16px;
  color: #546e7a;
  max-width: 720px;
  line-height: 1.7;
}

/* ---------- 区块标题 ---------- */

.section-title {
  font-size: 24px;
  font-weight: 700;
  color: #2c3e50;
  margin-bottom: 12px;
}

.section-desc {
  font-size: 15px;
  color: #546e7a;
  margin-bottom: 24px;
  max-width: 640px;
}

/* ---------- 按钮 ---------- */

.btn {
  display: inline-block;
  padding: 10px 24px;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 600;
  text-align: center;
  transition: background-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
}

.btn-primary {
  background-color: #1a73e8;
  color: #ffffff;
}

.btn-primary:hover {
  background-color: #1557b0;
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(26, 115, 232, 0.3);
}

.btn-secondary {
  background-color: #ffffff;
  color: #1a73e8;
  border: 1px solid #1a73e8;
}

.btn-secondary:hover {
  background-color: #e8f0fe;
  color: #1557b0;
}

/* ---------- 卡片 ---------- */

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

.card {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.card:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.1);
  transform: translateY(-2px);
}

.card-img {
  width: 100%;
  height: 140px;
  object-fit: cover;
  border-radius: 6px;
  margin-bottom: 16px;
}

.card-title {
  font-size: 18px;
  margin-bottom: 8px;
}

.card-text {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
  margin-bottom: 16px;
}

.card-link {
  font-size: 14px;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
}

.card-link::after {
  content: "→";
  margin-left: 6px;
  transition: transform 0.2s ease;
}

.card-link:hover::after {
  transform: translateX(3px);
}

/* ---------- 列表项 ---------- */

.post-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.post-item {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 20px 24px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease;
}

.post-item:hover {
  box-shadow: 0 2px 12px rgba(44, 62, 80, 0.08);
}

.post-title {
  font-size: 17px;
  margin-bottom: 6px;
}

.post-title a {
  color: #2c3e50;
}

.post-title a:hover {
  color: #1a73e8;
}

.post-excerpt {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
  margin-bottom: 8px;
}

.post-meta {
  font-size: 13px;
  color: #90a4ae;
}

/* ---------- 步骤 ---------- */

.steps-preview,
.steps-row {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.step-item {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
  position: relative;
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: #e8f0fe;
  color: #1a73e8;
  font-weight: 700;
  font-size: 15px;
  margin-bottom: 12px;
}

.step-title,
.step-name {
  font-size: 16px;
  margin-bottom: 8px;
}

.step-text,
.step-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
  margin-bottom: 12px;
}

.step-link {
  font-size: 14px;
  font-weight: 500;
}

/* ---------- 相关任务带 ---------- */

.related-tasks {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 24px;
}

.related-tasks-title,
.related-title {
  font-size: 22px;
  text-align: center;
  margin-bottom: 24px;
}

.task-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.task-link {
  display: block;
  background-color: #ffffff;
  border-radius: 8px;
  padding: 20px 24px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease, transform 0.2s ease;
  color: #2c3e50;
}

.task-link:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.1);
  transform: translateY(-2px);
  color: #1a73e8;
}

/* ---------- 步骤条 ---------- */

.task-strip {
  max-width: 1200px;
  margin: 0 auto;
  padding: 40px 24px;
}

.task-strip-inner {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.task-item,
.task-card {
  display: block;
  background-color: #ffffff;
  border-radius: 8px;
  padding: 20px 24px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease, transform 0.2s ease;
  color: #2c3e50;
}

.task-item:hover,
.task-card:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.1);
  transform: translateY(-2px);
  color: #1a73e8;
}

.task-title,
.task-card-title {
  display: block;
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}

.task-desc,
.task-card-desc {
  display: block;
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
}

/* ---------- FAQ ---------- */

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  background-color: #ffffff;
  border-radius: 8px;
  border: 1px solid #e5e9f0;
  overflow: hidden;
}

.faq-question {
  padding: 18px 24px;
  font-size: 15px;
  font-weight: 600;
  color: #2c3e50;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  list-style: none;
}

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

.faq-question::after {
  content: "+";
  font-size: 20px;
  color: #1a73e8;
  flex-shrink: 0;
  margin-left: 16px;
}

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

.faq-answer {
  padding: 0 24px 18px;
  font-size: 14px;
  color: #546e7a;
  line-height: 1.7;
}

.faq-answer p {
  margin-bottom: 8px;
}

.faq-answer a {
  font-weight: 500;
}

/* ---------- 内容图片 ---------- */

.content-media {
  margin: 20px 0;
}

.content-media-inline {
  display: block;
}

.content-media-inline img {
  width: 100%;
  max-width: 640px;
  height: auto;
  border-radius: 8px;
}

.content-media-inline figcaption {
  font-size: 13px;
  color: #90a4ae;
  margin-top: 8px;
  max-width: 640px;
}

/* ---------- 警示框 ---------- */

.warning-box {
  background-color: #fdf0ef;
  border: 1px solid #f5c6c2;
  border-radius: 8px;
  padding: 20px 24px;
  margin-bottom: 24px;
}

.warning-title {
  font-size: 16px;
  font-weight: 700;
  color: #c0392b;
  margin-bottom: 12px;
}

.warning-box .rules-list li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 8px;
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
}

.warning-box .rules-list li::before {
  content: "•";
  position: absolute;
  left: 0;
  color: #e74c3c;
  font-weight: 700;
}

/* ---------- 规则列表 ---------- */

.rules-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.rules-list.ordered {
  counter-reset: rule-counter;
}

.rules-list.ordered li {
  position: relative;
  padding-left: 36px;
  counter-increment: rule-counter;
  font-size: 15px;
  line-height: 1.7;
  color: #37474f;
}

.rules-list.ordered li::before {
  content: counter(rule-counter);
  position: absolute;
  left: 0;
  top: 2px;
  width: 24px;
  height: 24px;
  border-radius: 50%;
  background-color: #e8f0fe;
  color: #1a73e8;
  font-size: 13px;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
}

.rules-list.ordered strong {
  color: #2c3e50;
}

/* ---------- 规则框 ---------- */

.rules-box {
  background-color: #e8f0fe;
  border-left: 4px solid #1a73e8;
  border-radius: 0 8px 8px 0;
  padding: 24px;
}

.rules-box .rules-list {
  margin-bottom: 16px;
}

.rules-box .rules-list li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 8px;
  font-size: 15px;
  line-height: 1.6;
}

.rules-box .rules-list li::before {
  content: "✓";
  position: absolute;
  left: 0;
  color: #1a73e8;
  font-weight: 700;
}

.text-link {
  font-size: 15px;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
}

.text-link::after {
  content: "→";
  margin-left: 6px;
}

/* ---------- 无障碍 ---------- */

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ==========================================================================
   pages
   ========================================================================== */

/* ---------- 首页 ---------- */

.home-main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

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

.hero-content {
  max-width: 560px;
}

.hero-title {
  font-size: 36px;
  font-weight: 700;
  color: #2c3e50;
  margin-bottom: 16px;
  line-height: 1.25;
}

.hero-description {
  font-size: 16px;
  color: #546e7a;
  line-height: 1.7;
  margin-bottom: 28px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.hero-figure {
  margin: 0;
}

.hero-figure img {
  width: 100%;
  height: auto;
  border-radius: 8px;
  box-shadow: 0 4px 20px rgba(44, 62, 80, 0.12);
}

.section {
  padding: 32px 0;
}

.quick-entry-section,
.hot-posts-section,
.rules-summary-section,
.guide-entry-section {
  border-bottom: 1px solid #e5e9f0;
}

.guide-entry-section {
  border-bottom: none;
}

/* ---------- 版块页 ---------- */

.forum-section,
.activity-section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

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

.forum-card {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease, transform 0.2s ease;
}

.forum-card:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.1);
  transform: translateY(-2px);
}

.forum-card-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}

.forum-icon {
  width: 48px;
  height: 48px;
  border-radius: 8px;
  object-fit: cover;
  flex-shrink: 0;
}

.forum-name {
  font-size: 17px;
  color: #2c3e50;
}

.forum-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
  margin-bottom: 12px;
}

.forum-meta {
  font-size: 13px;
  color: #90a4ae;
  margin-bottom: 12px;
}

.forum-link {
  font-size: 14px;
  font-weight: 500;
}

.activity-section {
  padding-top: 8px;
}

.activity-intro {
  font-size: 15px;
  color: #546e7a;
  margin-bottom: 20px;
}

.activity-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.activity-item {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 20px 24px;
  border: 1px solid #e5e9f0;
}

.activity-name {
  font-size: 16px;
  margin-bottom: 8px;
}

.activity-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
}

/* ---------- 热帖页 ---------- */

.hot-list-section,
.weekly-topics-section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

.hot-post-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.hot-post-item {
  display: grid;
  grid-template-columns: 40px 1fr 120px;
  gap: 16px;
  align-items: center;
  background-color: #ffffff;
  border-radius: 8px;
  padding: 16px 20px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease;
}

.hot-post-item:hover {
  box-shadow: 0 2px 12px rgba(44, 62, 80, 0.08);
}

.post-rank {
  font-size: 20px;
  font-weight: 700;
  color: #1a73e8;
  text-align: center;
}

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

.post-body .post-title {
  font-size: 16px;
  margin-bottom: 4px;
}

.post-body .post-excerpt {
  font-size: 14px;
  color: #546e7a;
  margin-bottom: 6px;
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
}

.post-meta {
  display: flex;
  gap: 16px;
  font-size: 13px;
  color: #90a4ae;
}

.post-replies {
  color: #1a73e8;
  font-weight: 500;
}

.post-date {
  color: #90a4ae;
}

.post-thumb {
  width: 120px;
  height: 72px;
  object-fit: cover;
  border-radius: 6px;
}

.weekly-topics-section {
  padding-top: 8px;
}

.topic-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.topic-tag {
  background-color: #ffffff;
  border-radius: 20px;
  border: 1px solid #e5e9f0;
  padding: 8px 18px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.topic-tag:hover {
  border-color: #1a73e8;
  background-color: #e8f0fe;
}

.topic-tag a {
  font-size: 14px;
  font-weight: 500;
  color: #2c3e50;
}

.topic-tag a:hover {
  color: #1a73e8;
}

.topic-count {
  font-size: 13px;
  color: #90a4ae;
}

/* ---------- 新手指南页 ---------- */

.guide-steps-nav,
.posting-guide,
.interaction-guide,
.guide-faq {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

.guide-steps-nav {
  padding-bottom: 8px;
}

.posting-steps {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.posting-step {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
  position: relative;
}

.posting-step-title {
  font-size: 17px;
  margin-bottom: 8px;
}

.posting-step-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.7;
  margin-bottom: 10px;
}

.posting-step-tip {
  font-size: 13px;
  color: #78909c;
  background-color: #f5f7fa;
  border-radius: 6px;
  padding: 12px 16px;
  line-height: 1.6;
}

.posting-step-tip a {
  font-weight: 500;
}

.interaction-list {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.interaction-item {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
}

.interaction-item-title {
  font-size: 16px;
  margin-bottom: 8px;
}

.interaction-item-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
}

/* ---------- 规则页 ---------- */

.rules-section {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

.section-intro {
  font-size: 15px;
  color: #546e7a;
  margin-bottom: 20px;
  max-width: 720px;
  line-height: 1.7;
}

.rules-section .warning-box {
  margin-top: 20px;
}

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

.process-step {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
  position: relative;
}

.step-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: #e8f0fe;
  color: #1a73e8;
  font-weight: 700;
  font-size: 15px;
  margin-bottom: 12px;
}

.step-content .step-title {
  font-size: 16px;
  margin-bottom: 8px;
}

.step-content .step-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
}

/* ---------- 反馈页 ---------- */

.feedback-types,
.feedback-process {
  max-width: 1200px;
  margin: 0 auto;
  padding: 24px;
}

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

.type-card {
  background-color: #ffffff;
  border-radius: 8px;
  padding: 24px;
  border: 1px solid #e5e9f0;
  transition: box-shadow 0.2s ease;
}

.type-card:hover {
  box-shadow: 0 4px 16px rgba(44, 62, 80, 0.08);
}

.type-name {
  font-size: 16px;
  margin-bottom: 8px;
}

.type-desc {
  font-size: 14px;
  color: #546e7a;
  line-height: 1.6;
}

.feedback-process {
  padding-top: 8px;
}

.task-links {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

/* ---------- 404 ---------- */

.error-main {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 80px 24px;
  text-align: center;
}

.error-panel {
  max-width: 560px;
  margin-bottom: 40px;
}

.error-code {
  font-size: 72px;
  font-weight: 700;
  color: #1a73e8;
  line-height: 1;
  margin-bottom: 16px;
}

.error-panel h1 {
  font-size: 28px;
  margin-bottom: 12px;
}

.error-desc {
  font-size: 16px;
  color: #546e7a;
  margin-bottom: 24px;
}

.btn-back {
  display: inline-block;
  padding: 10px 24px;
  border-radius: 6px;
  font-size: 15px;
  font-weight: 600;
  background-color: #1a73e8;
  color: #ffffff;
  transition: background-color 0.2s ease;
}

.btn-back:hover {
  background-color: #1557b0;
  color: #ffffff;
}

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

.error-link {
  display: inline-block;
  padding: 10px 20px;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 500;
  background-color: #ffffff;
  color: #1a73e8;
  border: 1px solid #e5e9f0;
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.error-link:hover {
  border-color: #1a73e8;
  background-color: #e8f0fe;
  color: #1557b0;
}

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

@media (max-width: 992px) {
  .card-grid {
    grid-template-columns: repeat(2, 1fr);
  }

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

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

  .footer-columns {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }

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

  .hero-content {
    max-width: 100%;
  }

  .hero-figure img {
    max-height: 320px;
    object-fit: cover;
  }
}

@media (max-width: 768px) {
  .header-inner {
    padding: 0 16px;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background-color: #ffffff;
    border-bottom: 1px solid #e5e9f0;
    box-shadow: 0 4px 12px rgba(44, 62, 80, 0.08);
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
  }

  .site-nav.is-open {
    max-height: 320px;
  }

  .nav-list {
    flex-direction: column;
    align-items: stretch;
    padding: 8px 16px 16px;
    gap: 2px;
  }

  .nav-list a {
    padding: 12px 16px;
    font-size: 16px;
  }

  .nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
  }

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

  .nav-toggle[aria-expanded="true"] .nav-toggle-bar:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
  }

  .home-main,
  .page-header,
  .breadcrumb,
  .related-tasks,
  .task-strip,
  .forum-section,
  .activity-section,
  .hot-list-section,
  .weekly-topics-section,
  .guide-steps-nav,
  .posting-guide,
  .interaction-guide,
  .guide-faq,
  .rules-section,
  .feedback-types,
  .feedback-process {
    padding-left: 16px;
    padding-right: 16px;
  }

  .hero-section {
    padding: 32px 0;
  }

  .hero-title {
    font-size: 28px;
  }

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

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

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

  .activity-list,
  .interaction-list,
  .process-steps,
  .task-strip-inner,
  .task-cards,
  .task-links {
    grid-template-columns: 1fr;
  }

  .hot-post-item {
    grid-template-columns: 32px 1fr;
  }

  .post-thumb {
    display: none;
  }

  .footer-columns {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 32px 16px 24px;
  }

  .footer-bottom {
    padding: 16px;
  }

  .error-main {
    padding: 48px 16px;
  }

  .error-code {
    font-size: 56px;
  }
}

@media (max-width: 480px) {
  .card-grid,
  .forum-grid,
  .type-grid {
    grid-template-columns: 1fr;
  }

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

  .hero-actions .btn {
    text-align: center;
  }

  .topic-tags {
    flex-direction: column;
    align-items: flex-start;
  }

  .topic-tag {
    width: 100%;
  }

  .post-meta {
    flex-wrap: wrap;
    gap: 8px;
  }
}