/* 深蓝科技风主题 CSS */
:root {
  --primary-color: #0b1a2e; /* 深蓝背景 */
  --secondary-color: #162f4f; /* 稍浅的蓝色模块 */
  --accent-color: #00e5ff; /* 霓虹青色高亮 */
  --accent-hover: #00b3cc;
  --text-main: #e0e6ed; /* 主文本 */
  --text-muted: #889bb0; /* 次级文本 */
  --bg-dark: #060d17; /* 最深底色 */
  --border-color: #234165;
  --card-bg: rgba(22, 47, 79, 0.7);
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--primary-color);
  color: var(--text-main);
  line-height: 1.6;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--accent-color);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: var(--accent-hover);
}

/* 导航栏 */
header {
  background-color: var(--bg-dark);
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: #fff;
  letter-spacing: 1px;
}

.brand span {
  color: var(--accent-color);
}

.nav-links {
  display: flex;
  gap: 1.5rem;
}

.nav-links a {
  color: var(--text-main);
  font-weight: 500;
}

.nav-links a:hover {
  color: var(--accent-color);
}

.menu-toggle {
  display: none;
  font-size: 1.5rem;
  cursor: pointer;
}

/* 按钮 */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  border-radius: 4px;
  font-weight: 600;
  text-align: center;
  transition: all 0.3s ease;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background-color: var(--accent-color);
  color: var(--bg-dark);
}

.btn-primary:hover {
  background-color: var(--accent-hover);
  color: #fff;
  box-shadow: 0 0 10px rgba(0, 229, 255, 0.5);
}

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

.btn-secondary:hover {
  background-color: rgba(0, 229, 255, 0.1);
}

/* 布局容器 */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

.section-title {
  text-align: center;
  font-size: 2rem;
  margin-bottom: 2rem;
  color: #fff;
}

/* Hero 区域 */
.hero {
  text-align: center;
  padding: 4rem 1rem;
  background: linear-gradient(180deg, var(--bg-dark) 0%, var(--primary-color) 100%);
}

.hero h1 {
  font-size: 2.5rem;
  color: #fff;
  margin-bottom: 1rem;
}

.hero p {
  font-size: 1.125rem;
  color: var(--text-muted);
  max-width: 800px;
  margin: 0 auto 2rem;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
}

/* 网格系统 */
.grid {
  display: grid;
  gap: 1.5rem;
}

.grid-3 {
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
}

.grid-2 {
  grid-template-columns: repeat(auto-fit, minmax(400px, 1fr));
}

/* 卡片 */
.card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 1.5rem;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: 0 10px 20px rgba(0,0,0,0.2);
  border-color: var(--accent-color);
}

.card h3 {
  color: #fff;
  margin-bottom: 1rem;
  font-size: 1.25rem;
}

/* 文章内容页 */
.article-container {
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

.article-header {
  margin-bottom: 2rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 1rem;
}

.article-header h1 {
  font-size: 2rem;
  color: #fff;
  margin-bottom: 0.5rem;
}

.article-content h2 {
  font-size: 1.5rem;
  color: var(--accent-color);
  margin: 2rem 0 1rem;
}

.article-content h3 {
  font-size: 1.25rem;
  color: #fff;
  margin: 1.5rem 0 0.5rem;
}

.article-content p {
  margin-bottom: 1rem;
}

.article-content ul, .article-content ol {
  margin-bottom: 1rem;
  padding-left: 1.5rem;
}

.article-content li {
  margin-bottom: 0.5rem;
}

.article-content strong {
  color: #fff;
}

/* FAQ 手风琴 */
.faq-item {
  border-bottom: 1px solid var(--border-color);
  padding: 1rem 0;
}

.faq-question {
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-weight: 600;
  color: #fff;
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease;
  color: var(--text-muted);
}

.faq-item.active .faq-answer {
  max-height: 500px;
  margin-top: 1rem;
}

.faq-icon {
  transition: transform 0.3s ease;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

/* 页脚 */
footer {
  background-color: var(--bg-dark);
  border-top: 1px solid var(--border-color);
  padding: 3rem 1rem 1rem;
  margin-top: 4rem;
}

.footer-content {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 2rem;
  margin-bottom: 2rem;
}

.footer-col h4 {
  color: #fff;
  margin-bottom: 1rem;
}

.footer-col ul {
  list-style: none;
}

.footer-col ul li {
  margin-bottom: 0.5rem;
}

.footer-bottom {
  text-align: center;
  padding-top: 1rem;
  border-top: 1px solid var(--border-color);
  color: var(--text-muted);
  font-size: 0.875rem;
}

/* 响应式 */
@media (max-width: 768px) {
  .menu-toggle {
    display: block;
  }
  
  .nav-links {
    display: none;
    flex-direction: column;
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    background: var(--bg-dark);
    padding: 1rem;
    border-bottom: 1px solid var(--border-color);
  }
  
  .nav-links.active {
    display: flex;
  }
  
  .hero-actions {
    flex-direction: column;
  }
  
  .grid-2 {
    grid-template-columns: 1fr;
  }
}