/* ============================================================
   学长的小仓库 —— 静态首页样式（蓝白配色，现代简洁风格）
   仅原生 CSS，无框架依赖。
   ============================================================ */

:root {
  --blue-50: #eff6ff;
  --blue-100: #dbeafe;
  --blue-200: #bfdbfe;
  --blue-500: #3b82f6;
  --blue-600: #2563eb;
  --blue-700: #1d4ed8;
  --blue-800: #1e40af;

  --bg: #f6f9ff;
  --surface: #ffffff;
  --border: #e2e8f0;

  --text: #0f172a;
  --text-2: #475569;
  --text-3: #94a3b8;

  --radius: 14px;
  --radius-sm: 8px;
  --shadow: 0 1px 2px rgba(15, 23, 42, 0.05), 0 8px 24px rgba(37, 99, 235, 0.07);
  --shadow-lg: 0 12px 32px rgba(37, 99, 235, 0.16);
  --transition: 0.2s ease;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ---------- 可访问性 ---------- */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

/* hidden 属性需覆盖 .state-panel 等 class 的 display 设置 */
[hidden] {
  display: none !important;
}

.skip-link {
  position: absolute;
  top: -48px;
  left: 12px;
  z-index: 100;
  padding: 10px 18px;
  background: var(--blue-700);
  color: #fff;
  border-radius: var(--radius-sm);
  text-decoration: none;
  transition: top var(--transition);
}

.skip-link:focus {
  top: 12px;
}

:focus-visible {
  outline: 3px solid var(--blue-500);
  outline-offset: 2px;
  border-radius: 4px;
}

/* ---------- 页头 ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--blue-700);
  text-decoration: none;
  font-weight: 700;
  font-size: 20px;
}

.brand-icon {
  width: 26px;
  height: 26px;
}

.main-nav {
  display: flex;
  gap: 6px;
}

.main-nav a {
  color: var(--text-2);
  text-decoration: none;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  transition: color var(--transition), background var(--transition);
}

.main-nav a:hover {
  color: var(--blue-700);
  background: var(--blue-50);
}

/* ---------- Hero 与搜索 ---------- */
.hero {
  background: linear-gradient(135deg, var(--blue-800) 0%, var(--blue-600) 60%, var(--blue-500) 100%);
  color: #fff;
  padding: 64px 0 72px;
}

.hero-inner {
  max-width: 820px;
  text-align: center;
}

.hero-title {
  margin: 0 0 12px;
  font-size: clamp(28px, 5vw, 42px);
  letter-spacing: 1px;
}

.hero-desc {
  margin: 0 auto 32px;
  max-width: 640px;
  font-size: clamp(14px, 2vw, 17px);
  color: var(--blue-100);
}

.search-form {
  position: relative;
  display: flex;
  align-items: center;
  background: #fff;
  border-radius: 999px;
  padding: 6px 6px 6px 18px;
  box-shadow: var(--shadow-lg);
}

.search-icon {
  flex: none;
  width: 20px;
  height: 20px;
  color: var(--text-3);
}

.search-form input[type="search"] {
  flex: 1;
  min-width: 0;
  border: none;
  outline: none;
  background: transparent;
  padding: 12px 14px;
  font-size: 16px;
  color: var(--text);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: none;
  border-radius: 999px;
  cursor: pointer;
  font-size: 15px;
  font-family: inherit;
  transition: background var(--transition), box-shadow var(--transition), transform var(--transition);
}

.btn-search {
  flex: none;
  background: var(--blue-600);
  color: #fff;
  padding: 12px 28px;
  font-weight: 600;
}

.btn-search:hover {
  background: var(--blue-700);
}

.btn-primary {
  background: var(--blue-600);
  color: #fff;
  padding: 10px 22px;
  font-weight: 600;
}

.btn-primary:hover {
  background: var(--blue-700);
}

.btn-ghost {
  background: var(--surface);
  color: var(--blue-700);
  border: 1px solid var(--blue-200);
  padding: 10px 18px;
  border-radius: var(--radius-sm);
}

.btn-ghost:hover {
  background: var(--blue-50);
  border-color: var(--blue-500);
}

/* ---------- 主体区块 ---------- */
.main-inner {
  padding-top: 28px;
  padding-bottom: 56px;
}

.section-block {
  margin-bottom: 24px;
}

/* 分类导航 */
.category-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.category-btn {
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text-2);
  padding: 9px 18px;
  border-radius: 999px;
  font-size: 14px;
  cursor: pointer;
  transition: all var(--transition);
}

.category-btn:hover {
  border-color: var(--blue-500);
  color: var(--blue-700);
}

.category-btn[aria-pressed="true"] {
  background: linear-gradient(135deg, var(--blue-600), var(--blue-500));
  border-color: transparent;
  color: #fff;
  font-weight: 600;
  box-shadow: var(--shadow);
}

/* 筛选栏 */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  gap: 14px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
}

.filter-field,
.sort-field {
  display: flex;
  flex-direction: column;
  gap: 6px;
  flex: 1 1 150px;
  min-width: 150px;
}

.filter-bar label,
.sort-field label {
  font-size: 13px;
  color: var(--text-2);
  font-weight: 600;
}

.filter-bar select,
.sort-field select {
  width: 100%;
  padding: 10px 12px;
  font-size: 14px;
  font-family: inherit;
  color: var(--text);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: border-color var(--transition);
}

.filter-bar select:hover,
.sort-field select:hover {
  border-color: var(--blue-500);
}

/* 结果工具栏 */
.results-toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.results-title {
  margin: 0;
  font-size: 20px;
}

.result-count {
  margin: 0 auto 0 8px;
  font-size: 14px;
  color: var(--text-2);
}

.sort-field {
  flex: 0 0 auto;
  min-width: 140px;
  flex-direction: row;
  align-items: center;
  gap: 8px;
}

.sort-field select {
  width: auto;
}

/* ---------- 资料卡片 ---------- */
.materials-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 18px;
}

.material-card {
  display: flex;
  flex-direction: column;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  box-shadow: var(--shadow);
  transition: transform var(--transition), box-shadow var(--transition);
}

.material-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

.card-top {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 10px;
}

.format-badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.5px;
}

.format-badge[data-format="PDF"] {
  color: #dc2626;
  background: #fee2e2;
}

.format-badge[data-format="PPTX"] {
  color: #ea580c;
  background: #ffedd5;
}

.format-badge[data-format="DOCX"] {
  color: var(--blue-700);
  background: var(--blue-100);
}

.format-badge[data-format="ZIP"] {
  color: #15803d;
  background: #dcfce7;
}

.format-badge[data-format="MP4"] {
  color: #6d28d9;
  background: #ede9fe;
}

.category-chip {
  font-size: 12px;
  color: var(--blue-700);
  background: var(--blue-100);
  padding: 3px 10px;
  border-radius: 6px;
}

.card-top .category-chip {
  margin-left: auto;
}

.type-chip {
  font-size: 12px;
  color: var(--text-2);
  background: #f1f5f9;
  padding: 3px 10px;
  border-radius: 999px;
}

.material-title {
  margin: 0 0 8px;
  font-size: 16.5px;
  line-height: 1.45;
}

.material-desc {
  margin: 0 0 12px;
  font-size: 13.5px;
  color: var(--text-2);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-meta {
  list-style: none;
  margin: 0 0 12px;
  padding: 0;
  display: grid;
  gap: 5px;
  font-size: 13px;
  color: var(--text-2);
}

.card-meta li {
  display: flex;
  align-items: center;
  gap: 7px;
}

.card-meta svg {
  flex: none;
  width: 15px;
  height: 15px;
  color: var(--text-3);
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-bottom: 14px;
}

.tag {
  font-size: 12px;
  color: var(--blue-700);
  background: var(--blue-50);
  border: 1px solid var(--blue-100);
  padding: 2px 9px;
  border-radius: 999px;
}

.card-footer {
  margin-top: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  border-top: 1px solid var(--border);
  padding-top: 14px;
}

.download-btn {
  background: var(--blue-600);
  color: #fff;
  border: none;
  padding: 9px 20px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: background var(--transition);
}

.download-btn:hover {
  background: var(--blue-700);
}

a.download-btn {
  text-decoration: none;
}

.download-btn.is-unavailable,
.download-btn:disabled {
  background: #cbd5e1;
  color: #f8fafc;
  cursor: not-allowed;
}

.download-btn.is-unavailable:hover,
.download-btn:disabled:hover {
  background: #cbd5e1;
}

.download-btn svg {
  width: 15px;
  height: 15px;
}

.download-count {
  font-size: 12px;
  color: var(--text-3);
}

/* ---------- 加载指示 ---------- */
.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--blue-100);
  border-top-color: var(--blue-600);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  margin-bottom: 10px;
}

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

/* ---------- 空结果 / 错误状态 ---------- */
.state-panel {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  gap: 6px;
  padding: 64px 24px;
  background: var(--surface);
  border: 1px dashed var(--blue-200);
  border-radius: var(--radius);
}

.state-icon {
  font-size: 44px;
  line-height: 1;
  margin-bottom: 10px;
}

.state-title {
  margin: 0;
  font-size: 18px;
  font-weight: 600;
}

.state-text {
  margin: 0 0 6px;
  color: var(--text-2);
  font-size: 14px;
  max-width: 420px;
}

.state-panel .btn {
  margin-top: 12px;
}

/* ---------- 页脚 ---------- */
.site-footer {
  background: var(--surface);
  border-top: 1px solid var(--border);
  padding: 28px 0;
}

.footer-inner {
  text-align: center;
  color: var(--text-3);
  font-size: 13px;
}

.footer-name {
  margin: 0 0 4px;
  color: var(--text-2);
  font-weight: 600;
}

.footer-note {
  margin: 0;
}

.footer-demo {
  margin: 8px 0 0;
}

.footer-demo a {
  color: var(--blue-500);
  text-decoration: none;
}

.footer-demo a:hover {
  text-decoration: underline;
}

/* ---------- 响应式：平板 / 手机 ---------- */
@media (max-width: 768px) {
  .hero {
    padding: 44px 0 52px;
  }

  .header-inner {
    height: 56px;
  }

  .brand-name {
    font-size: 17px;
  }

  .main-nav a {
    padding: 6px 10px;
    font-size: 14px;
  }

  .filter-bar {
    padding: 14px;
  }

  .filter-field {
    flex: 1 1 calc(50% - 8px);
    min-width: 0;
  }

  .results-toolbar {
    gap: 8px;
  }

  .result-count {
    margin-left: 0;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 14px;
  }

  .search-form {
    padding: 4px 4px 4px 14px;
  }

  .btn-search {
    padding: 11px 18px;
    font-size: 14px;
  }

  .search-form input[type="search"] {
    padding: 11px 10px;
  }

  .main-nav a {
    padding: 6px 8px;
    font-size: 13px;
  }

  .category-nav {
    flex-wrap: nowrap;
    overflow-x: auto;
    padding-bottom: 6px;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }

  .category-nav::-webkit-scrollbar {
    display: none;
  }

  .category-btn {
    flex: none;
  }

  .materials-grid {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .sort-field {
    width: 100%;
    justify-content: space-between;
  }

  .sort-field select {
    flex: 1;
  }
}