/* ===== 全局重置 ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --primary: #6C5CE7;
  --primary-light: #A29BFE;
  --secondary: #FDCB6E;
  --accent: #FF7675;
  --bg: #F8F9FE;
  --card-bg: #FFFFFF;
  --text: #2D3436;
  --text-light: #636E72;
  --shadow: 0 4px 20px rgba(108, 92, 231, 0.12);
  --shadow-hover: 0 8px 30px rgba(108, 92, 231, 0.2);
  --radius: 14px;
  --radius-sm: 8px;
  --header-h: 60px;
  --max-w: 1300px;
  --font-title: 18px;
  --font-body: 14px;
  --font-note: 12px;
}

html {
  font-size: var(--font-body);
  line-height: 1.6;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  overflow-x: hidden;
  padding-bottom: 80px;
}

/* ===== 头部导航 ===== */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: linear-gradient(135deg, var(--primary), var(--primary-light));
  box-shadow: 0 2px 15px rgba(108, 92, 231, 0.3);
  padding: 0 16px;
  height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 16px;
}

.header-logo {
  color: #fff;
  font-size: 22px;
  font-weight: 700;
  white-space: nowrap;
  cursor: pointer;
  user-select: none;
}

.search-box {
  flex: 1;
  max-width: 500px;
  position: relative;
}

.search-box input {
  width: 100%;
  padding: 10px 40px 10px 16px;
  border: none;
  border-radius: 25px;
  font-size: 14px;
  background: rgba(255,255,255,0.9);
  outline: none;
  transition: box-shadow 0.2s;
}

.search-box input:focus {
  box-shadow: 0 0 0 3px rgba(255,255,255,0.4);
}

.search-box .search-icon {
  position: absolute;
  right: 14px;
  top: 50%;
  transform: translateY(-50%);
  pointer-events: none;
  opacity: 0.5;
}

.btn-home {
  background: rgba(255,255,255,0.2);
  color: #fff;
  border: 1px solid rgba(255,255,255,0.4);
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 13px;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.2s;
}

.btn-home:hover {
  background: rgba(255,255,255,0.35);
}

/* ===== 主体布局 ===== */
.main {
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 24px 16px;
  min-height: calc(100vh - var(--header-h) - 60px);
}

/* ===== 面包屑 ===== */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  margin-bottom: 20px;
  font-size: var(--font-note);
  color: var(--text-light);
  flex-wrap: wrap;
}

.breadcrumb span {
  cursor: pointer;
  transition: color 0.2s;
}

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

.breadcrumb .sep {
  opacity: 0.4;
  pointer-events: none;
}

.breadcrumb .current {
  color: var(--primary);
  font-weight: 600;
  pointer-events: none;
}

/* ===== 板块入口卡片 ===== */
.section-title {
  font-size: var(--font-title);
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

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

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

.board-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
  border: 2px solid transparent;
  position: relative;
  overflow: hidden;
}

.board-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: var(--card-color, var(--primary));
  border-radius: 4px 0 0 4px;
}

.board-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-hover);
  border-color: var(--card-color, var(--primary-light));
}

.board-card .card-icon {
  font-size: 32px;
  margin-bottom: 10px;
  display: block;
}

.board-card .card-name {
  font-size: var(--font-title);
  font-weight: 700;
  margin-bottom: 4px;
}

.board-card .card-desc {
  font-size: var(--font-note);
  color: var(--text-light);
}

.board-card .card-count {
  position: absolute;
  top: 16px;
  right: 16px;
  background: var(--card-color, var(--primary));
  color: #fff;
  font-size: 11px;
  padding: 2px 8px;
  border-radius: 10px;
  opacity: 0.8;
}

/* ===== 子项目网格 ===== */
.sub-items {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.sub-item {
  background: var(--card-bg);
  border-radius: var(--radius-sm);
  padding: 14px 10px;
  text-align: center;
  box-shadow: var(--shadow);
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
  border: 1px solid rgba(0,0,0,0.04);
}

.sub-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
}

.sub-item .sub-icon {
  font-size: 28px;
  margin-bottom: 6px;
}

.sub-item .sub-name {
  font-size: var(--font-body);
  font-weight: 600;
}

/* ===== 内容区 ===== */
.content-area {
  margin-top: 8px;
}

.content-area.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 200px;
  gap: 16px;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--primary-light);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.content-error {
  text-align: center;
  padding: 40px 20px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.content-error .error-icon {
  font-size: 48px;
  margin-bottom: 12px;
}

.content-error p {
  color: var(--text-light);
  margin-bottom: 16px;
}

.btn-retry {
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 10px 28px;
  border-radius: 20px;
  font-size: var(--font-body);
  cursor: pointer;
  transition: background 0.2s;
}

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

.placeholder-content {
  text-align: center;
  padding: 60px 20px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.placeholder-content .placeholder-icon {
  font-size: 56px;
  margin-bottom: 16px;
}

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

.placeholder-content p {
  color: var(--text-light);
  font-size: var(--font-body);
}

/* ===== 精华卡片 ===== */
.card-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 18px 20px;
  box-shadow: var(--shadow);
  border-left: 4px solid var(--primary);
  transition: box-shadow 0.2s, border-color 0.2s;
  position: relative;
}

.card.speaking {
  border-color: var(--secondary);
  box-shadow: 0 0 0 3px rgba(253, 203, 110, 0.3);
}

.card .card-title {
  font-size: var(--font-title);
  font-weight: 700;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.card .card-title-text {
  display: flex;
  align-items: center;
  gap: 8px;
}

.card .card-icon {
  font-size: 20px;
}

.btn-speak {
  background: var(--primary-light);
  color: #fff;
  border: none;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  cursor: pointer;
  font-size: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: background 0.2s;
}

.btn-speak:hover {
  background: var(--primary);
}

.btn-speak.active {
  background: var(--secondary);
}

.card .card-core,
.card .card-formula,
.card .card-example {
  margin-bottom: 8px;
  font-size: var(--font-body);
  line-height: 1.7;
}

.card .card-core strong,
.card .card-formula strong,
.card .card-example strong {
  font-weight: 600;
}

.card .card-formula {
  background: #FFF8E1;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
}

.card .card-detail {
  margin-bottom: 8px;
  font-size: var(--font-body);
  line-height: 1.7;
  background: #F0F4FF;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--primary);
}

.card .card-original {
  margin-bottom: 8px;
  font-size: var(--font-body);
  line-height: 1.9;
  background: #FAF6EF;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  border-left: 3px solid #C9A87C;
  color: #4a3f30;
  font-family: 'Kaiti SC', 'KaiTi', 'STKaiti', serif;
}

.card .card-original strong {
  font-weight: 600;
  color: #8B6F4E;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Microsoft YaHei', sans-serif;
}

.card .card-detail strong {
  font-weight: 600;
}

.card .detail-link {
  display: inline-block;
  margin-top: 8px;
  color: var(--primary);
  font-size: var(--font-note);
  text-decoration: none;
  cursor: pointer;
}

.card .detail-link:hover {
  text-decoration: underline;
}

/* ===== 搜索结果 ===== */
.search-results {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
}

.search-results h3 {
  margin-bottom: 16px;
  font-size: var(--font-title);
}

.search-results .result-item {
  padding: 12px;
  border-bottom: 1px solid rgba(0,0,0,0.06);
  cursor: pointer;
  transition: background 0.15s;
  border-radius: var(--radius-sm);
}

.search-results .result-item:hover {
  background: rgba(108, 92, 231, 0.05);
}

.search-results .result-item:last-child {
  border-bottom: none;
}

.search-results .result-title {
  font-weight: 600;
  margin-bottom: 4px;
}

.search-results .result-path {
  font-size: var(--font-note);
  color: var(--text-light);
}

/* ===== 页脚 ===== */
.footer {
  text-align: center;
  padding: 20px 16px;
  font-size: var(--font-note);
  color: var(--text-light);
  border-top: 1px solid rgba(0,0,0,0.06);
  background: var(--card-bg);
}

/* ===== 返回顶部 ===== */
.btn-top {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 44px;
  height: 44px;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 50%;
  font-size: 18px;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(108, 92, 231, 0.4);
  z-index: 999;
  display: none;
  align-items: center;
  justify-content: center;
  transition: transform 0.2s, background 0.2s;
}

.btn-top.visible {
  display: flex;
}

.btn-top:hover {
  transform: translateY(-2px);
  background: var(--primary-light);
}

/* ===== 响应式 ===== */
@media (max-width: 1024px) {
  .card-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .card-grid.cols-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  .main {
    padding: 16px 12px;
  }
}

@media (max-width: 768px) {
  :root {
    --font-title: 16px;
    --font-body: 13px;
    --font-note: 11px;
    --header-h: 56px;
  }
  .header {
    flex-wrap: wrap;
    height: auto;
    padding: 10px 12px;
    gap: 10px;
  }
  .header-logo {
    font-size: 18px;
  }
  .search-box {
    order: 3;
    max-width: 100%;
    flex-basis: 100%;
  }
  .btn-home {
    font-size: 12px;
    padding: 6px 12px;
  }
  .card-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }
  .card-grid.cols-2 {
    grid-template-columns: 1fr;
  }
  .sub-items {
    grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
    gap: 8px;
  }
  .sub-item {
    padding: 10px 6px;
  }
  .sub-item .sub-icon {
    font-size: 22px;
  }
  .board-card {
    padding: 16px;
  }
  .board-card .card-icon {
    font-size: 26px;
  }
  .card {
    padding: 14px 16px;
  }
  .btn-top {
    bottom: 16px;
    right: 16px;
    width: 40px;
    height: 40px;
  }
}

@media (max-width: 480px) {
  .sub-items {
    grid-template-columns: repeat(2, 1fr);
  }
  .header-logo {
    font-size: 16px;
  }
}

/* ===== 底部广告横幅（两条） ===== */
.ad-banner-wrap {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  z-index: 999;
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.15);
}

.ad-banner-item {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  height: 38px;
  font-size: 13px;
  text-decoration: none;
  color: #fff;
  letter-spacing: 0.3px;
  transition: opacity 0.15s;
}

.ad-banner-item:hover {
  opacity: 0.88;
}

.ad-banner-item .ad-icon {
  font-size: 16px;
  flex-shrink: 0;
}

.ad-banner-item .ad-text {
  opacity: 0.95;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.ad-banner-item .ad-arrow {
  font-size: 14px;
  opacity: 0.7;
  flex-shrink: 0;
}

.ad-banner-agent {
  background: linear-gradient(135deg, #f59e0b, #f97316);
}

.ad-banner-free {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
}

@keyframes adSlideUp {
  from { transform: translateY(100%); }
  to { transform: translateY(0); }
}

.ad-banner-wrap {
  animation: adSlideUp 0.4s ease-out;
}

@media (max-width: 480px) {
  .ad-banner-item {
    height: 32px;
    font-size: 11px;
    gap: 4px;
  }
  .ad-banner-item .ad-icon {
    font-size: 14px;
  }
}

/* ===== 动画 ===== */
.fade-in {
  animation: fadeIn 0.3s ease-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}