/* ========== 公共基础样式 ========== */
* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; line-height: 1.8; color: #333; background: #f8f9fa; }
.container { max-width: 900px; margin: 0 auto; padding: 20px; }
header { background: linear-gradient(135deg, #1a73e8, #0d47a1); color: #fff; padding: 40px 20px; text-align: center; }
header h1 { font-size: 2em; margin-bottom: 10px; }
header p { opacity: 0.9; font-size: 1.05em; }
.breadcrumb { padding: 15px 20px; background: #fff; border-bottom: 1px solid #e0e0e0; font-size: 0.9em; }
.breadcrumb a { color: #1a73e8; text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }
article { background: #fff; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.08); margin: 20px 0; padding: 40px; }
article h2 { font-size: 1.5em; color: #1a73e8; margin: 30px 0 15px; border-left: 4px solid #1a73e8; padding-left: 15px; }
article h3 { font-size: 1.2em; margin: 20px 0 10px; color: #444; }
article p { margin-bottom: 16px; text-indent: 2em; }
article ul, article ol { margin: 10px 0 20px 30px; }
article li { margin-bottom: 8px; }
.faq-section { margin-top: 40px; padding-top: 30px; border-top: 2px solid #e8e8e8; }
.faq-section h2 { border-left-color: #ff6d00; color: #ff6d00; }
.faq-item { background: #fafafa; border-radius: 8px; padding: 20px; margin-bottom: 15px; border-left: 3px solid #ff6d00; }
.faq-item .question { font-weight: bold; font-size: 1.1em; color: #333; margin-bottom: 10px; }
.faq-item .answer { color: #555; }
.footer { background: #263238; color: #b0bec5; padding: 30px 20px; text-align: center; font-size: 0.9em; line-height: 2; }
.footer strong { color: #fff; }
.footer a { color: #64b5f6; text-decoration: none; }
.back-home { display: inline-block; margin-top: 20px; padding: 10px 25px; background: #1a73e8; color: #fff; border-radius: 6px; text-decoration: none; }
.back-home:hover { background: #0d47a1; }

.nav-links { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin-top: 15px; }
.nav-links a { color: #fff; text-decoration: none; padding: 6px 12px; border-radius: 4px; font-size: 0.95em; transition: background 0.2s; }
.nav-links a:hover { background: rgba(255,255,255,0.15); }
.data-bar { background: #fff; border-bottom: 1px solid #e0e0e0; padding: 16px 0; }
.data-items { display: flex; justify-content: center; gap: 32px; flex-wrap: wrap; }
.data-items span { font-size: 1em; color: #444; }
.data-items strong { color: #1a73e8; font-size: 1.3em; }
.cta-section { background: linear-gradient(135deg, #1a237e, #0d47a1); color: #fff; text-align: center; padding: 40px 20px; border-radius: 8px; margin: 30px 0 20px; }
.cta-section h2 { font-size: 1.6em; margin-bottom: 12px; border: none; padding: 0; }
.cta-section p { margin-bottom: 10px; text-indent: 0; }
.cta-btn { display: inline-block; margin-top: 12px; padding: 12px 30px; background: #fff; color: #1a237e; border-radius: 6px; text-decoration: none; font-weight: 600; }
.cta-btn:hover { background: #e3f2fd; }

/* 学科专题下拉菜单 */
.nav-links { position: relative; }
.dropdown { position: relative; display: inline-block; }
.dropdown-toggle { color: #fff; text-decoration: none; padding: 6px 12px; border-radius: 4px; font-size: 0.95em; cursor: pointer; background: none; border: none; font-family: inherit; }
.dropdown-toggle:hover { background: rgba(255,255,255,0.15); }
.dropdown-menu { display: none; position: absolute; top: 100%; left: 0; background: #fff; min-width: 180px; border-radius: 6px; box-shadow: 0 4px 16px rgba(0,0,0,0.15); z-index: 100; padding: 8px 0; }
.dropdown:hover .dropdown-menu { display: block; }
.dropdown-menu a { display: block; color: #333 !important; padding: 8px 18px; font-size: 0.9em; text-decoration: none; white-space: nowrap; }
.dropdown-menu a:hover { background: #e8f0fe; color: #1a73e8 !important; }
.dropdown-section-label { display: block; color: #999 !important; padding: 6px 18px 2px; font-size: 0.78em; text-transform: uppercase; letter-spacing: 0.5px; cursor: default; border-top: 1px solid #eee; margin-top: 4px; }
.dropdown-section-label:hover { background: transparent !important; color: #999 !important; }
.dropdown-section-label:first-child { border-top: none; margin-top: 0; }

/* ========== 移动端汉堡菜单 ========== */
.nav-toggle { display: none; }
.nav-toggle-label { display: none; cursor: pointer; padding: 8px; position: absolute; right: 16px; top: 50%; transform: translateY(-50%); z-index: 200; }
.nav-toggle-label span { display: block; width: 26px; height: 3px; background: #fff; margin: 5px 0; border-radius: 2px; transition: all 0.3s ease; }
.nav-links { transition: max-height 0.3s ease; }

/* 汉堡菜单动画 */
.nav-toggle:checked ~ .nav-toggle-label span:nth-child(1) { transform: rotate(45deg) translate(5px, 6px); }
.nav-toggle:checked ~ .nav-toggle-label span:nth-child(2) { opacity: 0; }
.nav-toggle:checked ~ .nav-toggle-label span:nth-child(3) { transform: rotate(-45deg) translate(5px, -6px); }

/* 移动端下拉菜单 */
.dropdown-menu.open { display: block !important; }

/* ========== 响应式：平板 768px ========== */
@media (max-width: 768px) {
  html { font-size: 14px; }
  header { padding: 20px 12px; }
  header h1 { font-size: 1.5em; }
  .container { padding: 12px; }
  article { padding: 20px 16px; margin: 12px 0; }
  article h2 { font-size: 1.3em; margin: 20px 0 12px; padding-left: 12px; }
  article p { text-indent: 1.5em; margin-bottom: 12px; font-size: 0.95em; line-height: 1.75; }
  article ul, article ol { margin: 8px 0 16px 20px; }
  .breadcrumb { padding: 10px 12px; font-size: 0.85em; }

  /* 汉堡菜单 */
  .nav-toggle-label { display: block; }
  .nav-links { display: flex; flex-direction: column; max-height: 0; overflow: hidden; gap: 0; margin-top: 0; position: relative; }
  .nav-toggle:checked ~ .nav-links { max-height: 2000px; }
  .nav-links a { display: block; padding: 10px 16px; border-bottom: 1px solid rgba(255,255,255,0.1); font-size: 1em; text-align: left; }
  .nav-links .dropdown { display: block; }
  .nav-links .dropdown-toggle { display: block; padding: 10px 16px; border-bottom: 1px solid rgba(255,255,255,0.1); text-align: left; }
  .dropdown-menu { position: static; background: rgba(255,255,255,0.08); border-radius: 0; box-shadow: none; min-width: auto; }
  .dropdown-menu a { color: rgba(255,255,255,0.85) !important; padding: 8px 32px; font-size: 0.9em; border-bottom: 1px solid rgba(255,255,255,0.06); }
  .dropdown-menu a:hover { background: rgba(255,255,255,0.1) !important; color: #fff !important; }
  .dropdown:hover .dropdown-menu { display: none; }

  /* 表格横向滚动 */
  table { display: block; overflow-x: auto; white-space: nowrap; max-width: 100%; }
  img { max-width: 100%; height: auto; }

  /* 按钮 */
  .back-home, .cta-btn { padding: 12px 24px; font-size: 1em; min-height: 44px; display: inline-flex; align-items: center; }
}

/* ========== 响应式：手机 480px ========== */
@media (max-width: 480px) {
  html { font-size: 13px; }
  header { padding: 16px 8px; }
  header h1 { font-size: 1.3em; }
  article { padding: 14px 10px; border-radius: 4px; }
  article h2 { font-size: 1.15em; border-left-width: 3px; }
  article p { text-indent: 1.2em; font-size: 0.93em; line-height: 1.7; }
  .breadcrumb { font-size: 0.8em; padding: 8px 8px; }
  .footer { padding: 20px 12px; font-size: 0.85em; }

  /* 按钮全宽 */
  .back-home, .cta-btn { width: 100%; justify-content: center; text-align: center; min-height: 48px; font-size: 1.05em; }
  .cta-section { padding: 24px 12px; }
  .cta-section h2 { font-size: 1.2em; }

  /* 面包屑简化 */
  .breadcrumb .container { padding: 0 4px; }
}

@media (max-width: 600px) { article { padding: 20px; } header h1 { font-size: 1.5em; } }