/* EnterScholar - 黑白极简风格 */

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

:root {
  --black: #000;
  --white: #fff;
  --gray-100: #f5f5f5;
  --gray-200: #e5e5e5;
  --gray-300: #d4d4d4;
  --gray-600: #525252;
  --gray-800: #262626;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.6;
  color: var(--black);
  background: var(--white);
}

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

a:hover {
  text-decoration: underline;
}

/* 容器 */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

/* 导航 */
.nav {
  border-bottom: 1px solid var(--gray-200);
  padding: 16px 0;
  position: sticky;
  top: 0;
  background: var(--white);
  z-index: 100;
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 16px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 18px;
}

.nav-brand svg {
  flex-shrink: 0;
}

.nav-menu {
  display: flex;
  gap: 24px;
  list-style: none;
  flex-wrap: wrap;
}

.nav-menu a {
  font-size: 14px;
  color: var(--gray-600);
  transition: color 0.2s;
}

.nav-menu a:hover,
.nav-menu a.active {
  color: var(--black);
}

/* Hero 区域 */
.hero {
  padding: 80px 0;
  text-align: center;
  border-bottom: 1px solid var(--gray-200);
}

.hero h1 {
  font-size: 48px;
  font-weight: 800;
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.hero p {
  font-size: 18px;
  color: var(--gray-600);
  max-width: 600px;
  margin: 0 auto;
}

/* 页面标题 */
.page-header {
  padding: 60px 0 40px;
  border-bottom: 1px solid var(--gray-200);
}

.page-header h1 {
  font-size: 36px;
  font-weight: 700;
  margin-bottom: 8px;
}

.page-header p {
  color: var(--gray-600);
}

/* 分类网格 */
.category-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
  padding: 40px 0;
}

.category-card {
  border: 1px solid var(--gray-200);
  padding: 24px;
  transition: border-color 0.2s;
}

.category-card:hover {
  border-color: var(--black);
}

.category-card h3 {
  font-size: 18px;
  margin-bottom: 8px;
}

.category-card p {
  font-size: 14px;
  color: var(--gray-600);
  margin-bottom: 16px;
}

.category-card .count {
  font-size: 12px;
  color: var(--gray-600);
}

/* 工具列表 */
.tool-list {
  padding: 40px 0;
}

.tool-section {
  margin-bottom: 48px;
}

.tool-section h2 {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 2px solid var(--black);
}

.tool-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 16px;
}

.tool-item {
  border: 1px solid var(--gray-200);
  padding: 20px;
  transition: all 0.2s;
}

.tool-item:hover {
  border-color: var(--black);
  background: var(--gray-100);
}

.tool-item h3 {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.tool-item h3 a {
  display: flex;
  align-items: center;
  gap: 8px;
}

.tool-item h3 a::after {
  content: '↗';
  font-size: 12px;
  opacity: 0.5;
}

.tool-item p {
  font-size: 14px;
  color: var(--gray-600);
  margin-bottom: 8px;
}

.tool-item .url {
  font-size: 12px;
  color: var(--gray-600);
  word-break: break-all;
}

/* 标签 */
.tag {
  display: inline-block;
  font-size: 11px;
  padding: 2px 8px;
  background: var(--gray-100);
  border: 1px solid var(--gray-200);
  margin-right: 4px;
  margin-bottom: 4px;
}

.tag-free {
  background: var(--black);
  color: var(--white);
  border-color: var(--black);
}

.tag-cn {
  border-color: var(--gray-600);
}

/* 页脚 */
.footer {
  border-top: 1px solid var(--gray-200);
  padding: 40px 0;
  margin-top: 60px;
}

.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 16px;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
}

.footer-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.footer-links a {
  font-size: 14px;
  color: var(--gray-600);
}

.footer-copy {
  font-size: 12px;
  color: var(--gray-600);
}

/* 响应式 */
@media (max-width: 768px) {
  .hero h1 {
    font-size: 32px;
  }
  
  .nav-menu {
    gap: 12px;
  }
  
  .nav-menu a {
    font-size: 13px;
  }
  
  .category-grid,
  .tool-grid {
    grid-template-columns: 1fr;
  }
}