/* ========================================
   Web Tutorial — 首页专有样式
   ======================================== */

:root {
  --color-primary: #2563eb;        /* 主蓝色 */
  --color-primary-light: #60a5fa;  /* 浅蓝 (hero标题) */
  --color-primary-border: #93c5fd; /* 蓝边框 (卡片hover) */
  --color-primary-shadow: rgba(37,99,235,0.12); /* 阴影 (卡片hover) */
  --color-accent: #f59e0b;         /* 橙色点缀 */
  --color-heading: #1e293b;        /* 标题/深色背景 */
  --color-text: #334155;           /* 正文 */
  --color-muted: #64748b;          /* 次要文字 */
  --color-light: #94a3b8;          /* 更浅文字 */
  --color-border: #e2e8f0;        /* 边框 */
  --color-border-light: #e8ecf1;  /* 浅边框 */
  --color-bg-hover: #f1f5f9;      /* 悬停背景 */
  --color-bg-card: #f8fafc;       /* 卡片背景 */
  --color-bg-active: #eff6ff;     /* 激活项背景 */
  --color-bg-badge: #dbeafe;      /* 标签背景 */
  --color-scrollbar: #cbd5e1;     /* 滚动条 */
  --color-white: #fff;            /* 白色 */
}

/* ---------- 顶部导航 ---------- */
.header {
  position: sticky; top: 0; z-index: 200;
  background: var(--color-white);
  width: 100%;
}

/* 第一行：Logo + 语言切换 */
.header-top {
  border-bottom: 1px solid var(--color-border-light);
  padding: 0 28px;
  height: 72px;
  display: flex;
  align-items: center;
}
.header-inner {
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.header-left {
  display: flex;
  align-items: center;
  gap: 16px;
}
.logo {
  font-size: 42px;
  font-weight: 800;
  color: var(--color-primary);
  letter-spacing: -0.5px;
}
.logo span { color: var(--color-accent); }
.logo .com {
  font-size: 22px;
  font-weight: 600;
  color: var(--color-light);
  margin-left: 2px;
}

/* 第二行：导航条（9分类下拉菜单） */
.sub-nav {
  display: flex;
  align-items: center;
  background: #2563eb;
  padding: 0 28px;
  height: 44px;
  gap: 0;
}
.sub-nav-item {
  position: relative;
  height: 100%;
  flex-shrink: 0;
}
.sub-nav-link {
  padding: 0 18px;
  font-size: 14px;
  font-weight: 500;
  color: rgba(255,255,255,0.85);
  text-decoration: none;
  white-space: nowrap;
  height: 100%;
  display: flex;
  align-items: center;
  transition: all 0.2s;
  border-bottom: 3px solid transparent;
  cursor: pointer;
}
.sub-nav-link:hover {
  color: #fff;
  background: rgba(255,255,255,0.1);
  border-bottom-color: var(--color-accent);
}

/* 主页图标 */
.sub-nav-home {
  font-size: 18px;
  padding: 0 14px;
  line-height: 1;
  flex-shrink: 0;
}

/* 下拉菜单 */
.sub-nav-dropdown {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  min-width: 180px;
  background: #fff;
  border: 1px solid var(--color-border);
  border-top: 2px solid var(--color-accent);
  border-radius: 0 0 6px 6px;
  box-shadow: 0 8px 24px rgba(0,0,0,0.12);
  z-index: 300;
  padding: 6px 0;
}
.sub-nav-item:hover .sub-nav-dropdown {
  display: block;
}
.sub-nav-dropdown a {
  display: block;
  padding: 8px 20px;
  font-size: 13px;
  color: var(--color-text);
  text-decoration: none;
  white-space: nowrap;
  transition: all 0.15s;
}
.sub-nav-dropdown a:hover {
  background: var(--color-bg-active);
  color: var(--color-primary);
}

/* ---------- 汉堡菜单按钮 ---------- */
.menu-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  width: 32px; height: 32px;
  flex-direction: column;
  justify-content: space-around;
  align-items: center;
}
.menu-toggle span {
  display: block;
  width: 22px; height: 2.5px;
  background: var(--color-text);
  border-radius: 2px;
  transition: all 0.3s;
}
.menu-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.menu-toggle.open span:nth-child(2) { opacity: 0; }
.menu-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ---------- 遮罩层 ---------- */
.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.4);
  z-index: 99;
  opacity: 0;
  transition: opacity 0.3s;
}
.overlay.show {
  display: block;
  opacity: 1;
}

/* ---------- 语言切换 ---------- */
.lang-switch {
  display: flex;
  gap: 12px;
  align-items: center;
}
.lang-switch a {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  opacity: 0.5;
  transition: all 0.2s;
  line-height: 0;
  text-decoration: none;
  position: relative;
}
.lang-switch a:hover {
  opacity: 0.8;
}
.lang-switch a.active {
  opacity: 1;
}
.lang-switch a img {
  width: 28px; height: 21px;
  display: block;
}

/* ---------- 手机端语言下拉 ---------- */
.lang-mobile {
  display: none;
  position: absolute;
  right: 16px;
  top: 50%;
  transform: translateY(-50%);
}
.lang-mobile select {
  appearance: none;
  -webkit-appearance: none;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 6px;
  padding: 4px 24px 4px 8px;
  font-size: 12px;
  color: var(--color-text);
  cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2364748b' stroke-width='2' stroke-linecap='round' stroke-linejoin='round'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 4px center;
}

.lang-switch a::after {
  content: '';
  display: block;
  width: 0;
  height: 2px;
  background: var(--color-primary);
  border-radius: 1px;
  transition: width 0.2s;
}
.lang-switch a.active::after {
  width: 100%;
}

/* ---------- 左栏导航 ---------- */
.sidebar {
  width: 240px;
  flex-shrink: 0;
  background: var(--color-white);
  border-right: 1px solid var(--color-border-light);
  padding: 12px 0;
  overflow-y: auto;
  height: calc(100vh - 116px);
  position: sticky;
  top: 116px;
}
.sidebar-section { 
  margin-bottom: 2px; 
}
.sidebar-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--color-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 16px 20px 8px;
  display: flex;
  align-items: center;
  gap: 10px;
}
.sidebar-title::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--color-border);
}
.sidebar-section:last-child .sidebar-title::after {
  display: none;
}
.sidebar a {
  display: block;
  padding: 7px 20px 7px 56px;
  font-size: 14px;
  color: var(--color-text);
  transition: all 0.15s;
  border-left: 3px solid transparent;
  position: relative;
}
.sidebar a:hover {
  background: var(--color-bg-hover);
  color: var(--color-primary);
  border-left-color: var(--color-primary);
}
.sidebar a::before {
  content: '';
  position: absolute;
  left: 40px;
  top: 50%;
  transform: translateY(-50%);
  width: 8px;
  height: 8px;
  border: 2px solid var(--color-light);
  border-radius: 50%;
  background: transparent;
  transition: all 0.15s;
}
.sidebar a:hover::before {
  background: var(--color-accent);
  border-color: var(--color-accent);
}
.sidebar a.active {
  background: var(--color-bg-active);
  color: var(--color-primary);
  border-left-color: var(--color-primary);
  font-weight: 600;
}

/* ---------- 侧栏滚动条 ---------- */
.sidebar::-webkit-scrollbar {
  width: 5px;
}
.sidebar::-webkit-scrollbar-track {
  background: transparent;
}
.sidebar::-webkit-scrollbar-thumb {
  background: var(--color-scrollbar);
  border-radius: 10px;
}
.sidebar::-webkit-scrollbar-thumb:hover {
  background: var(--color-light);
}

/* ---------- 主内容区 ---------- */
.main {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
}

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(135deg, var(--color-heading) 0%, var(--color-text) 100%);
  color: var(--color-white);
  padding: 64px 48px;
  text-align: center;
}
.hero h1 {
  font-size: 40px;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}
.hero h1 span { color: var(--color-primary-light); }
.hero p {
  font-size: 17px;
  color: var(--color-scrollbar);
  max-width: 600px;
  margin: 0 auto 20px;
}
.hero-tags {
  display: flex;
  gap: 10px;
  justify-content: center;
  flex-wrap: wrap;
}
.hero-tags span {
  display: inline-block;
  padding: 5px 16px;
  border-radius: 100px;
  font-size: 13px;
  font-weight: 500;
  background: rgba(255,255,255,0.1);
  color: var(--color-border);
  border: 1px solid rgba(255,255,255,0.08);
}
.hero-cta {
  display: inline-block;
  margin-top: 24px;
  padding: 12px 32px;
  border-radius: 8px;
  background: var(--color-primary);
  color: var(--color-white);
  font-size: 16px;
  font-weight: 700;
  text-decoration: none;
  transition: all 0.2s;
}
.hero-cta:hover {
  background: var(--color-primary-light);
  transform: translateY(-1px);
}

/* ---------- 特色区块 ---------- */
.features {
  background: var(--color-white);
  border-bottom: 1px solid var(--color-border-light);
}
.features .g-row { gap: 0; }
.feature-item {
  padding: 32px 28px;
  text-align: center;
  border-right: 1px solid var(--color-border-light);
  transition: background 0.2s;
}
.feature-item:last-child { border-right: none; }
.feature-item:hover { background: var(--color-bg-card); }
.feature-icon { font-size: 32px; margin-bottom: 10px; }
.faq-letter {
  display: inline-block;
  width: 26px;
  height: 26px;
  border-radius: 4px;
  font-size: 15px;
  font-weight: 700;
  text-align: center;
  line-height: 26px;
  margin-right: 8px;
  vertical-align: middle;
}
.faq-letter.f {
  background: var(--color-primary);
  color: var(--color-white);
}
.faq-letter.q {
  background: var(--color-accent);
  color: var(--color-white);
}
.feature-item h3 {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 4px;
  text-align: left;
}
.feature-item p {
  font-size: 13px;
  color: var(--color-muted);
  text-align: left;
}

/* ---------- TIOBE 热点排行 ---------- */
.tiobe-section {
  padding: 40px 40px 32px;
  background: #fff;
  text-align: center;
}
.tiobe-section h2 {
  font-size: 33px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 4px;
}
.tiobe-badge {
  display: inline-block;
  font-size: 12px;
  font-weight: 500;
  color: var(--color-primary);
  background: var(--color-bg-badge);
  padding: 2px 10px;
  border-radius: 10px;
  vertical-align: middle;
  margin-left: 6px;
}
.tiobe-subtitle {
  font-size: 13px;
  color: var(--color-muted);
  margin-bottom: 20px;
}
.tiobe-card {
  position: relative;
}
.tiobe-rank {
  position: absolute;
  top: 6px;
  right: 8px;
  font-size: 11px;
  font-weight: 700;
  color: var(--color-muted);
  background: var(--color-border-light);
  padding: 1px 7px;
  border-radius: 8px;
  line-height: 1.6;
}
.tiobe-rank.r1 { color: #fff; background: #f59e0b; }
.tiobe-rank.r2 { color: #fff; background: #94a3b8; }
.tiobe-rank.r3 { color: #fff; background: #cd7f32; }

/* ---------- 技术卡片 ---------- */
.tech-grid-section {
  padding: 48px 40px;
  background: var(--color-white);
}
.tech-grid-section h2 {
  font-size: 42px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 32px;
  text-align: center;
}
.tech-category {
  font-size: 22px;
  font-weight: 700;
  color: var(--color-heading);
  margin: 0 0 18px;
  text-align: center;
}

/* 分类分组：交替背景色区分 */
.tech-group {
  padding: 60px 40px;
  margin: 0 -40px;
}
.tech-group:nth-child(even) {
  background: var(--color-bg-card);
}
.tech-grid-section .g-auto-5 {
  gap: 20px;
}
.tech-card {
  position: relative;
  background: var(--color-bg-card);
  border: 1px solid var(--color-border);
  border-radius: 14px;
  padding: 38px 0 0;
  text-align: center;
  transition: all 0.25s;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-start;
  overflow: hidden;
}
.tech-card::after {
  display: flex;
  align-items: flex-end;
  justify-content: flex-start;
  position: absolute;
  top: -23px;
  right: -23px;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--color-primary);
  z-index: 2;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  padding: 3px 0 10px 8px;
  color: var(--color-white);
  font-size: 10px;
  font-weight: 700;
  line-height: 1.1;
  pointer-events: none;
  opacity: 0;
  content: attr(data-desc);
}
.tech-card.hot::after {
  opacity: 1;
  content: attr(data-badge);
}
.tech-card:hover::after {
  opacity: 1;
  top: 0;
  right: 0;
  width: 100%;
  height: calc(100% - 42px);
  border-radius: 14px 14px 0 0;
  align-items: center;
  justify-content: center;
  padding: 20px;
  font-size: 14px;
  text-align: center;
  line-height: 1.5;
  white-space: pre-line;
  content: attr(data-desc);
}
.tech-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 24px var(--color-primary-shadow);
  border-color: var(--color-primary-border);
}
.tech-card .icon {
  font-size: 56px;
  margin-bottom: 14px;
  display: block;
  line-height: 1;
}
.tech-card i, .tech-card .icon-svg, .tech-card .devicon {
  font-size: 56px;
  margin-bottom: 14px;
  display: block;
  line-height: 1;
}
.tech-card .devicon { width: 56px; height: 56px; margin-left: auto; margin-right: auto; }
.tech-card .icon-svg {
  width: 56px;
  height: 56px;
  margin-left: auto;
  margin-right: auto;
}
.tech-card h4 {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-heading);
  margin-top: 4px;
  margin-bottom: 14px;
}
.tech-card .badge {
  display: inline-block;
  font-size: 11px;
  padding: 2px 10px;
  border-radius: 100px;
  background: var(--color-bg-badge);
  color: var(--color-primary);
  font-weight: 600;
  margin-top: 8px;
  margin-bottom: 12px;
}

/* ---------- 卡片底部三按钮 ---------- */
.tech-card-btns {
  display: flex;
  width: 100%;
  margin-top: auto;
  border-top: 1px solid var(--color-border);
}
.tech-card-btns a {
  flex: 1;
  text-align: center;
  padding: 9px 4px;
  font-size: 13px;
  font-weight: 600;
  color: var(--color-muted);
  transition: all 0.15s;
  text-decoration: none;
  border-right: 1px solid var(--color-border);
}
.tech-card-btns a:last-child {
  border-right: none;
}
.tech-card-btns a:first-child {
  border-radius: 0 0 0 14px;
}
.tech-card-btns a:last-child {
  border-radius: 0 0 14px 0;
}
.tech-card-btns a:hover {
  background: var(--color-primary);
  color: var(--color-white);
}

/* ---------- SEO 描述区 ---------- */
.seo-content {
  padding: 48px 40px;
  background: var(--color-white);
}
.seo-content h2 {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 20px;
  text-align: center;
}
.seo-content p {
  font-size: 15px;
  color: var(--color-muted);
  line-height: 1.8;
  margin-bottom: 14px;
}

/* ---------- FAQ 区 ---------- */
.seo-faq {
  padding: 48px 40px 56px;
  background: var(--color-bg-card);
}
.seo-faq h2 {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 28px;
  text-align: center;
}
.faq-item {
  max-width: 800px;
  margin: 0 auto 20px;
  padding: 20px 24px;
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 10px;
}
.faq-item:last-child {
  margin-bottom: 0;
}
.faq-item h3 {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 8px;
}
.faq-item p {
  font-size: 14px;
  color: var(--color-muted);
  line-height: 1.7;
  margin: 0;
}

/* 手机端 */
@media (max-width: 768px) {
  .seo-content { padding: 32px 20px; }
  .seo-content h2 { font-size: 22px; }
  .seo-content p { font-size: 14px; }
  .seo-faq { padding: 32px 16px 40px; }
  .seo-faq h2 { font-size: 22px; }
  .faq-item { padding: 16px 18px; }
  .faq-item h3 { font-size: 15px; }
  .faq-item p { font-size: 13px; }
}

/* ---------- FAQ 网格（新版，4列栅格） ---------- */
.faq-grid {
  padding: 48px 40px 56px;
  background: var(--color-bg-card);
  border-bottom: 1px solid var(--color-border-light);
}
.faq-grid-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 28px;
  text-align: center;
}
.faq-grid .g-auto-4 {
  gap: 20px;
}
.faq-card {
  background: var(--color-white);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 20px 20px 24px;
  transition: all 0.2s;
}
.faq-card:hover {
  border-color: var(--color-primary-border);
  box-shadow: 0 4px 12px var(--color-primary-shadow);
}
.faq-card h3 {
  font-size: 16px;
  font-weight: 700;
  color: var(--color-heading);
  margin-bottom: 8px;
}
.faq-card p {
  font-size: 14px;
  color: var(--color-muted);
  line-height: 1.7;
  margin: 0;
}

@media (max-width: 768px) {
  .faq-grid { padding: 32px 16px 40px; }
  .faq-grid-title { font-size: 22px; }
  .faq-card { padding: 16px 16px 20px; }
  .faq-card h3 { font-size: 15px; }
  .faq-card p { font-size: 13px; }
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--color-heading);
  color: var(--color-light);
  padding: 40px 32px 24px;
  font-size: 13px;
  margin-top: auto;
}
.footer-inner {
  max-width: none;
  margin: 0;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 32px;
}
.footer-col {
  flex: 1;
  min-width: 160px;
}
.footer-col h4 {
  color: var(--color-border);
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 10px;
}
.footer-col p, .footer-col a {
  color: var(--color-light);
  display: block;
  margin-bottom: 4px;
}
.footer-col a:hover { color: var(--color-primary-light); }
.footer-bottom {
  text-align: center;
  padding-top: 24px;
  margin-top: 24px;
  border-top: 1px solid var(--color-text);
  font-size: 12px;
  color: var(--color-muted);
}

/* ---------- 焦点样式 (无障碍) ---------- */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: 2px;
}
a:focus-visible,
button:focus-visible,
summary:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: 2px;
}

/* ---------- 回到顶部浮动按钮 ---------- */
#backTop {
  position: fixed;
  right: 24px;
  bottom: 32px;
  z-index: 999;
  width: 40px;
  height: 40px;
  border-radius: 8px;
  border: none;
  background: var(--color-primary);
  color: var(--color-white);
  font-size: 20px;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(37,99,235,0.3);
  transition: all 0.2s;
  opacity: 0;
  pointer-events: none;
  line-height: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}

#backTop.show {
  opacity: 1;
  pointer-events: auto;
}

#backTop:hover {
  background: var(--color-accent);
  transform: translateY(-3px);
  box-shadow: 0 6px 16px rgba(245,158,11,0.35);
}

/* ---------- 响应式 — 首页断点 ---------- */

/* 宽屏 5列不变 (>1400px 默认5列) */

/* ≤1400px 变4列 */
@media (max-width: 1400px) {
  .g-auto-5 { grid-template-columns: repeat(4, 1fr); }
}

/* 平板 */
@media (max-width: 1024px) {
  .sidebar { width: 210px; }
  .hero { padding: 48px 32px; }
  .hero h1 { font-size: 32px; }
  .tech-grid-section { padding: 32px 24px; }
  .g-auto-5 { grid-template-columns: repeat(3, 1fr); }
}

/* 手机 */
@media (max-width: 768px) {
  /* 手机端隐藏 Hero/SEO/FAQ 文字区，HTML 保留不影响 SEO */
  .hero, .seo-content, .faq-grid { display: none; }
  #backTop { right: 16px; bottom: 24px; width: 44px; height: 44px; font-size: 18px; }
  .menu-toggle { display: flex; width: 44px; height: 44px; padding: 8px; }
  /* LOGO 居中，菜单按钮在左侧 */
  .header-top .header-inner {
    justify-content: center;
    position: relative;
  }
  .header-top .header-left {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    gap: 8px;
  }
  .lang-switch { display: none; }
  .lang-mobile { display: flex; }
  .sub-nav { display: none; }
  /* 手机端 features 改为1列垂直排列 */
  .features { display: block; }
  .features .g-row { display: flex; flex-direction: column; gap: 0; }
  .tiobe-section { padding: 28px 16px 24px; }
  .tiobe-section h2 { font-size: 22px; }
  .tiobe-badge { font-size: 11px; }
  .tiobe-subtitle { font-size: 12px; }
  .sidebar {
    position: fixed;
    top: 116px;
    left: -280px;
    width: 260px;
    height: calc(100vh - 116px);
    z-index: 100;
    transition: left 0.3s ease;
    box-shadow: 2px 0 20px rgba(0,0,0,0.1);
  }
  .sidebar.open { left: 0; }
  .sidebar a { padding: 7px 20px 7px 30px; }
  .sidebar a::before { left: 16px; }
  .header { padding: 0 16px; }
  .logo { font-size: 30px; }
  .logo .com { font-size: 16px; }
  .hero { padding: 32px 16px; }
  .hero h1 { font-size: 22px; }
  .hero p { font-size: 14px; }
  .hero-cta { font-size: 14px; padding: 10px 24px; margin-top: 18px; }
  .hero-tags { gap: 6px; }
  .hero-tags span { font-size: 11px; padding: 3px 10px; }
  .feature-item {
    border-right: none;
    border-bottom: 1px solid var(--color-border-light);
    padding: 20px 16px;
  }
  .feature-item:last-child { border-bottom: none; }
  .feature-icon { font-size: 28px; }
  .feature-item h3 { font-size: 15px; }
  .feature-item p { font-size: 12px; }
  .tech-grid-section { padding: 24px 16px; }
  .tech-grid-section h2 { font-size: 26px; margin-bottom: 20px; }
  .tech-group { padding: 32px 16px; margin: 0 -16px; }
  .tech-category { font-size: 16px; margin: 0 0 12px; }
  .g-auto-5 { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .tech-card { padding: 16px 6px 0; min-height: 130px; }
  .tech-card i, .tech-card .icon-svg { font-size: 36px; margin-bottom: 8px; }
  .tech-card .devicon { width: 36px; height: 36px; }
  .tech-card h4 { font-size: 13px; margin-bottom: 8px; }
  .tech-card .icon-svg { width: 36px; height: 36px; }
  .tech-card-btns a { font-size: 11px; padding: 10px 4px; }
  .tech-card::after { top: -18px; right: -18px; width: 42px; height: 42px; padding: 2px 0 6px 5px; font-size: 9px; }
  .tech-card.hot:hover::after { font-size: 12px; padding: 12px; }
  .footer { padding: 28px 20px 20px; }
  .footer-inner { flex-direction: column; gap: 20px; }
  .footer-col { min-width: 100%; }
  .footer-col h4 { font-size: 13px; }
  .lang-switch a img { width: 22px; height: 16px; }
  .lang-switch { gap: 8px; }
}

/* 小手机 */
@media (max-width: 480px) {
  .g-auto-5 { grid-template-columns: repeat(2, 1fr); }
  .hero h1 { font-size: 20px; }
  .hero-cta { font-size: 13px; padding: 8px 20px; margin-top: 14px; }
  .hero-tags span { font-size: 10px; padding: 2px 8px; }
  .tech-card { padding: 12px 4px 0; min-height: 110px; }
  .tech-card i, .tech-card .icon-svg { font-size: 28px; }
  .tech-card .devicon { width: 28px; height: 28px; }
  .tech-card h4 { font-size: 12px; }
  .tech-card-btns a { font-size: 10px; padding: 5px 2px; }
}

/* ---------- 移动端侧栏手风琴菜单 ---------- */
.sidebar-accordion { display: none; }
.sidebar-accordion h3 {
  font-size: 14px; font-weight: 600; color: var(--color-heading);
  padding: 12px 20px; margin: 0; cursor: pointer;
  border-bottom: 1px solid var(--color-border-light);
  display: flex; justify-content: space-between; align-items: center;
}
.sidebar-accordion h3::after {
  content: '+'; font-size: 16px; font-weight: 400; color: var(--color-muted);
  transition: transform 0.3s;
}
.sidebar-accordion h3.open::after {
  content: '−'; transform: rotate(0deg);
}
.sidebar-accordion .acc-panel {
  display: none; padding: 6px 0;
}
.sidebar-accordion .acc-panel.open { display: block; }
.sidebar-accordion .acc-panel a {
  display: block; padding: 7px 20px 7px 36px;
  font-size: 13px; color: var(--color-text); text-decoration: none;
  transition: all 0.15s;
}
.sidebar-accordion .acc-panel a:hover { background: var(--color-bg-hover); color: var(--color-primary); }

@media (max-width: 768px) {
  .sidebar-accordion { display: block; }
}

/* ---------- 页脚小号文字 ---------- */
.footer-sm {
  font-size: 12px;
  color: var(--color-light);
  line-height: 1.8;
}
.footer-sm-link {
  display: block;
  margin-top: 4px;
  font-size: 12px;
}
.footer-col > .footer-sm-link:first-of-type {
  margin-top: 8px;
}

/* ========================================
   广告位预留 — 仅HTML标记，浏览器不可见
   Google AdSense 自动广告启用后自动填充
   ======================================== */

/* ---------- 通用：预留容器均隐藏 ---------- */
.ad-hero-bottom,
.ad-category-gap,
.ad-home-footer,
.sidebar-ads,
.ad-widget,
.ad-inline,
.ad-bottom,
.ad-interstitial,
.ad-interstitial-backdrop,
.ad-interstitial-modal,
.ad-interstitial-adzone,
.ad-interstitial-footer,
.ad-placeholder,
.ad-label {
  display: none;
}

/* ========== 施工页 (Construction Page) ========== */
.construction-hero {
  text-align:center; padding:80px 24px; max-width:720px; margin:0 auto;
}
.construction-icon {font-size:128px; margin-bottom:16px; line-height:1.2; }
.construction-icon svg.icon-svg { width:128px; height:128px; }

.construction-hero h1 {
  font-size:36px; color:var(--color-heading); margin-bottom:16px;
}
.construction-lead {
  font-size:17px; color:var(--color-text); line-height:1.8; margin-bottom:40px;
  text-align:left;
}
.construction-card {
  background:#fff; border:1px solid var(--color-border); border-radius:12px;
  padding:32px 40px; text-align:left; margin-bottom:32px;
  box-shadow:0 2px 12px rgba(0,0,0,0.04);
}
.construction-card h2 {
  font-size:24px; color:var(--color-heading); margin-bottom:12px;
}
.construction-card p {
  font-size:15px; color:var(--color-text-muted); line-height:1.8; margin-bottom:8px;
}
.construction-note { color:var(--color-accent, #2563eb) !important; }
.construction-links { margin-top:16px; }
.construction-links .btn-back {
  display:inline-block; padding:10px 28px; background:var(--color-accent, #2563eb);
  color:#fff; border-radius:8px; text-decoration:none; font-size:15px; font-weight:500;
  transition:opacity 0.2s;
}
.construction-links .btn-back:hover { opacity:0.88; }
@media (max-width:768px) {
  .construction-hero { padding:40px 16px; }
  .construction-hero h1 { font-size:28px; }
  .construction-card { padding:24px 20px; }
}