/* 全局样式 - 扁平化设计 */
:root {
  --primary-color: #2563eb;
  --secondary-color: #3b82f6;
  --background-color: #f8fafc;
  --card-color: #ffffff;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --border-color: #e2e8f0;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-hover: 0 4px 6px rgba(0, 0, 0, 0.1);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  background-color: var(--background-color);
  color: var(--text-primary);
  line-height: 1.6;
}

/* 头部样式 */
header {
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  color: white;
  padding: 3rem 1rem;
  text-align: center;
  box-shadow: var(--shadow);
}

header h1 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

header p {
  font-size: 1.125rem;
  opacity: 0.9;
}

/* 导航栏 */
nav {
  background-color: var(--card-color);
  border-bottom: 1px solid var(--border-color);
  padding: 1rem;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: var(--shadow);
}

nav .container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

nav .logo {
  font-weight: 700;
  font-size: 1.25rem;
  color: var(--primary-color);
  text-decoration: none;
}

nav .date-filter {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

nav .date-filter input {
  padding: 0.5rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 0.875rem;
}

nav .date-filter button {
  padding: 0.5rem 1rem;
  background-color: var(--primary-color);
  color: white;
  border: none;
  border-radius: 6px;
  font-size: 0.875rem;
  cursor: pointer;
  transition: background-color 0.2s;
}

nav .date-filter button:hover {
  background-color: var(--secondary-color);
}

/* 主内容区 */
main {
  max-width: 1200px;
  margin: 2rem auto;
  padding: 0 1rem;
}

/* 日期卡片 */
.date-card {
  background-color: var(--card-color);
  border-radius: 8px;
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  box-shadow: var(--shadow);
  transition: box-shadow 0.2s;
}

.date-card:hover {
  box-shadow: var(--shadow-hover);
}

.date-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
  padding-bottom: 0.75rem;
  border-bottom: 2px solid var(--border-color);
}

.date-header h2 {
  font-size: 1.5rem;
  color: var(--primary-color);
}

.date-header .badge {
  background-color: var(--success-color);
  color: white;
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
}

/* 更新项 */
.update-item {
  padding: 1rem 0;
  border-bottom: 1px solid var(--border-color);
}

.update-item:last-child {
  border-bottom: none;
}

.update-item h3 {
  font-size: 1.125rem;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.update-item .category {
  display: inline-block;
  background-color: #dbeafe;
  color: var(--primary-color);
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
}

.update-item p {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.7;
}

.update-item .source {
  margin-top: 0.5rem;
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

.update-item .source a {
  color: var(--primary-color);
  text-decoration: none;
}

.update-item .source a:hover {
  text-decoration: underline;
}

/* 空状态 */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--text-secondary);
}

.empty-state svg {
  width: 80px;
  height: 80px;
  margin-bottom: 1rem;
  opacity: 0.3;
}

.empty-state h3 {
  font-size: 1.25rem;
  margin-bottom: 0.5rem;
}

/* 页脚 */
footer {
  background-color: var(--card-color);
  border-top: 1px solid var(--border-color);
  padding: 2rem 1rem;
  text-align: center;
  color: var(--text-secondary);
  margin-top: 3rem;
}

footer a {
  color: var(--primary-color);
  text-decoration: none;
}

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

/* 响应式设计 */
@media (max-width: 768px) {
  header h1 {
    font-size: 2rem;
  }
  
  header p {
    font-size: 1rem;
  }
  
  nav .container {
    flex-direction: column;
    gap: 1rem;
  }
  
  .date-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
}

/* 加载动画 */
.loading {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 3rem;
}

.loading::after {
  content: '';
  width: 40px;
  height: 40px;
  border: 4px solid var(--border-color);
  border-top-color: var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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