/* 知识库系统样式 */

/* ========== 变量定义 ========== */
:root {
  --primary: #2563EB;
  --primary-hover: #1d4ed8;
  --secondary: #64748b;
  --accent: #10B981;
  --background: #F8FAFC;
  --card-bg: #FFFFFF;
  --text-primary: #1E293B;
  --text-secondary: #64748B;
  --border: #E2E8F0;
  --shadow: 0 1px 3px rgba(0,0,0,0.1), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.1), 0 4px 6px -2px rgba(0,0,0,0.05);
  --radius: 8px;
  --radius-lg: 12px;
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--background);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
}

/* ========== 通用组件 ========== */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* ========== 头部 ========== */
.header {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  padding: 16px 0;
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: var(--primary);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: 18px;
}

.logo-text {
  font-size: 20px;
  font-weight: 600;
  color: var(--text-primary);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* ========== 按钮 ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s ease;
  text-decoration: none;
}

.btn-primary {
  background: var(--primary);
  color: white;
}

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

.btn-secondary {
  background: var(--background);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-danger {
  background: #ef4444;
  color: white;
}

.btn-danger:hover {
  background: #dc2626;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 13px;
}

.btn-icon {
  padding: 8px;
  width: 36px;
  height: 36px;
}

/* ========== 搜索框 ========== */
.search-container {
  padding: 24px 0;
}

.search-box {
  position: relative;
  max-width: 600px;
  margin: 0 auto;
}

.search-icon {
  position: absolute;
  left: 16px;
  top: 50%;
  transform: translateY(-50%);
  color: var(--secondary);
  pointer-events: none;
}

.search-input {
  width: 100%;
  padding: 14px 20px 14px 48px;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  font-size: 15px;
  background: var(--card-bg);
  transition: all 0.2s ease;
}

.search-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

/* ========== 分类标签 ========== */
.categories-nav {
  padding: 16px 0;
  border-bottom: 1px solid var(--border);
  margin-bottom: 24px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

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

.categories-list {
  display: flex;
  gap: 12px;
  min-width: max-content;
}

.category-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 16px;
  border-radius: 20px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  background: var(--card-bg);
  border: 1px solid var(--border);
  cursor: pointer;
  transition: all 0.2s ease;
  white-space: nowrap;
}

.category-tag:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.category-tag.active {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.category-count {
  background: rgba(255,255,255,0.2);
  padding: 2px 8px;
  border-radius: 10px;
  font-size: 12px;
}

.category-tag:not(.active) .category-count {
  background: var(--background);
}

/* ========== 资料网格 ========== */
.resources-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
  gap: 24px;
  padding-bottom: 40px;
}

/* ========== 资料卡片 ========== */
.resource-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border);
  overflow: hidden;
  transition: all 0.2s ease;
  cursor: pointer;
}

.resource-card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  border-color: var(--primary);
}

.resource-thumbnail {
  position: relative;
  aspect-ratio: 16/9;
  background: var(--background);
  overflow: hidden;
}

.resource-thumbnail img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.resource-thumbnail-placeholder {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--secondary);
}

.resource-type-badge {
  position: absolute;
  top: 12px;
  right: 12px;
  padding: 4px 10px;
  border-radius: 12px;
  font-size: 12px;
  font-weight: 500;
  background: rgba(0,0,0,0.6);
  color: white;
}

.resource-type-badge.video {
  background: var(--primary);
}

.resource-type-badge.document {
  background: var(--accent);
}

.play-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0.3);
  opacity: 0;
  transition: opacity 0.2s ease;
}

.resource-card:hover .play-overlay {
  opacity: 1;
}

.play-icon {
  width: 60px;
  height: 60px;
  background: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  font-size: 24px;
  box-shadow: var(--shadow-lg);
}

.resource-content {
  padding: 16px;
}

.resource-category {
  font-size: 12px;
  color: var(--primary);
  font-weight: 500;
  margin-bottom: 8px;
}

.resource-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
  line-height: 1.4;
}

.resource-description {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 12px;
}

.resource-problems {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}

.problem-tag {
  padding: 4px 10px;
  background: var(--background);
  border-radius: 12px;
  font-size: 12px;
  color: var(--text-secondary);
}

/* ========== 视频播放器模态框 ========== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.8);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease;
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal-content {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  max-width: 900px;
  width: 90%;
  max-height: 90vh;
  overflow: hidden;
  transform: scale(0.9);
  transition: transform 0.3s ease;
}

.modal-overlay.active .modal-content {
  transform: scale(1);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--border);
}

.modal-title {
  font-size: 16px;
  font-weight: 600;
}

.modal-close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: transparent;
  color: var(--secondary);
  cursor: pointer;
  border-radius: var(--radius);
  transition: all 0.2s ease;
}

.modal-close:hover {
  background: var(--background);
  color: var(--text-primary);
}

.modal-body {
  padding: 20px;
}

.video-player {
  width: 100%;
  aspect-ratio: 16/9;
  background: #000;
  border-radius: var(--radius);
  overflow: hidden;
}

.video-player video {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

/* ========== 登录页面 ========== */
.login-page {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.login-card {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  padding: 40px;
  width: 100%;
  max-width: 400px;
  box-shadow: var(--shadow-lg);
  text-align: center;
}

.login-logo {
  width: 64px;
  height: 64px;
  background: var(--primary);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 700;
  font-size: 28px;
  margin: 0 auto 24px;
}

.login-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.login-subtitle {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

.login-form {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.form-group {
  text-align: left;
}

.form-label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.form-input {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 15px;
  transition: all 0.2s ease;
}

.form-input:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-input.error {
  border-color: #ef4444;
}

.login-btn {
  width: 100%;
  padding: 14px;
  margin-top: 8px;
}

.login-error {
  color: #ef4444;
  font-size: 14px;
  margin-top: 12px;
  display: none;
}

.login-error.show {
  display: block;
  animation: shake 0.5s ease;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}

/* ========== Toast 提示 ========== */
.toast-container {
  position: fixed;
  top: 20px;
  right: 20px;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.toast {
  padding: 14px 20px;
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 280px;
  animation: slideIn 0.3s ease;
}

.toast.success {
  border-left: 4px solid var(--accent);
}

.toast.error {
  border-left: 4px solid #ef4444;
}

.toast.info {
  border-left: 4px solid var(--primary);
}

@keyframes slideIn {
  from {
    transform: translateX(100%);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

/* ========== 空状态 ========== */
.empty-state {
  text-align: center;
  padding: 60px 20px;
  color: var(--text-secondary);
}

.empty-icon {
  font-size: 48px;
  margin-bottom: 16px;
  opacity: 0.5;
}

.empty-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 8px;
}

.empty-description {
  font-size: 14px;
  max-width: 400px;
  margin: 0 auto;
}

/* ========== 加载状态 ========== */
.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px;
}

.spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* ========== 骨架屏 ========== */
.skeleton {
  background: linear-gradient(90deg, var(--border) 25%, var(--background) 50%, var(--border) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius);
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* ========== 响应式 ========== */
@media (max-width: 768px) {
  .header-content {
    flex-wrap: wrap;
  }

  .logo-text {
    font-size: 18px;
  }

  .resources-grid {
    grid-template-columns: 1fr;
  }

  .login-card {
    margin: 20px;
    padding: 30px;
  }

  .modal-content {
    width: 95%;
  }
}

/* ========== 搜索高亮 ========== */
.highlight {
  background: #fef08a;
  padding: 0 2px;
  border-radius: 2px;
}

/* ========== 确认对话框 ========== */
.confirm-dialog {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1500;
  opacity: 0;
  visibility: hidden;
  transition: all 0.2s ease;
}

.confirm-dialog.active {
  opacity: 1;
  visibility: visible;
}

.confirm-content {
  background: var(--card-bg);
  border-radius: var(--radius-lg);
  padding: 24px;
  max-width: 400px;
  width: 90%;
  text-align: center;
}

.confirm-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
}

.confirm-message {
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.confirm-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
}