* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

:root {
  --sky-blue: #00bfff;
  --dark-bg: #0a101f;
  --card-bg: #121a29;
  --text-white: #ffffff;
  --text-gray: #b0b8c4;
  --hover: #0099cc;
}

body {
  background-color: var(--dark-bg);
  color: var(--text-white);
  line-height: 1.6;
}

.container {
  width: 90%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 15px;
}

/* 导航栏 */
header {
  padding: 20px 0;
  position: sticky;
  top: 0;
  background-color: var(--dark-bg);
  z-index: 999;
  border-bottom: 1px solid #1e293b;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

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

.logo {
  width: 40px;
  height: 40px;
  object-fit: contain;
}

.brand {
  font-size: 24px;
  font-weight: 700;
  color: var(--sky-blue);
}

.nav-btn {
  padding: 10px 20px;
  background: transparent;
  border: 2px solid var(--sky-blue);
  border-radius: 8px;
  color: var(--sky-blue);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
}

.nav-btn.active {
  background: var(--sky-blue);
  color: #fff;
}

/* 首页英雄区 */
.hero {
  padding: 60px 0;
  text-align: center;
}
.hero h1 {
  font-size: 42px;
  margin-bottom: 15px;
  color: var(--text-white);
}
.hero p {
  font-size: 18px;
  color: var(--text-gray);
  max-width: 700px;
  margin: 0 auto 40px;
}

/* 下载卡片 */
.download-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin: 40px 0;
}
.download-card {
  background: var(--card-bg);
  padding: 25px 20px;
  border-radius: 12px;
  text-align: center;
  transition: 0.3s;
  border: 1px solid transparent;
}
.download-card:hover {
  border-color: var(--sky-blue);
  transform: translateY(-5px);
}
.download-card i {
  font-size: 32px;
  color: var(--sky-blue);
  margin-bottom: 15px;
}
.download-card h3 {
  color: var(--text-white);
  margin-bottom: 15px;
  font-size: 16px;
}
.download-btn {
  display: inline-block;
  padding: 10px 18px;
  color: var(--sky-blue);
  font-weight: 600;
  border: 1px solid var(--sky-blue);
  border-radius: 8px;
  text-decoration: none;
  transition: 0.3s;
}
.download-btn:hover {
  background: var(--sky-blue);
  color: #fff;
}

/* 模块标题 */
.section-title {
  font-size: 28px;
  text-align: center;
  margin: 60px 0 30px;
  color: var(--text-white);
}

/* 文章列表 */
.article-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(350px, 1fr));
  gap: 20px;
  margin-bottom: 50px;
}
.article-item {
  background: var(--card-bg);
  padding: 20px;
  border-radius: 10px;
  display: flex;
  align-items: flex-start;
  gap: 15px;
}
.article-item i {
  color: var(--sky-blue);
  font-size: 24px;
  margin-top: 5px;
}
.article-content h4 {
  color: var(--text-white);
  margin-bottom: 8px;
  font-size: 16px;
}
.article-content p {
  color: var(--text-gray);
  font-size: 14px;
  display: -webkit-box;
  -webkit-line-clamp: 4;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* 用户评价 */
.review-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 20px;
}
.review-item {
  background: var(--card-bg);
  padding: 25px;
  border-radius: 12px;
}
.review-item i {
  color: var(--sky-blue);
  font-size: 20px;
  margin-bottom: 15px;
}
.review-item p {
  color: var(--text-gray);
  font-size: 14px;
  margin-bottom: 10px;
  line-height: 1.5;
}
.review-item .name {
  color: var(--sky-blue);
  font-weight: 600;
}

/* 404页面 */
.page-404 {
  height: 80vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
}
.page-404 h1 {
  font-size: 80px;
  color: var(--sky-blue);
}
.page-404 h2 {
  font-size: 24px;
  margin: 20px 0;
}
.page-404 a {
  margin-top: 30px;
}

/* 页脚 */
footer {
  padding: 30px 0;
  text-align: center;
  border-top: 1px solid #1e293b;
  margin-top: 60px;
  color: var(--text-gray);
}