/* 基础样式 */
:root {
  --primary-color: #1a1a1a;
  --accent-color: #f7931a; /* 比特币橙 */
  --bg-color: #ffffff;
  --text-color: #333333;
  --light-gray: #f5f5f5;
  --border-color: #e0e0e0;
  --nav-bg: rgba(255, 255, 255, 0.95);
}

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

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

/* 导航栏 */
nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--nav-bg);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  padding: 0.8rem 2rem;
  z-index: 1000;
  display: flex;
  justify-content: space-between;
  align-items: center;
  box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

nav .logo {
  font-size: 1.4rem;
  font-weight: bold;
  color: var(--primary-color);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

nav .logo span {
  display: inline-block;
}

nav ul {
  display: flex;
  list-style: none;
  gap: 2rem;
  align-items: center;
}

nav a {
  text-decoration: none;
  color: var(--text-color);
  transition: all 0.3s;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.95rem;
}

nav a:hover,
nav a.active {
  color: var(--accent-color);
  font-weight: 500;
}

nav a.active {
  position: relative;
}

nav a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-color);
  border-radius: 1px;
}

/* 汉堡菜单（移动端） */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 5px;
}

.hamburger span {
  width: 25px;
  height: 2px;
  background: var(--primary-color);
  transition: all 0.3s;
}

/* 主内容 */
main {
  max-width: 900px;
  margin: 80px auto 40px;
  padding: 0 1.5rem;
}

/* 页脚 */
footer {
  text-align: center;
  padding: 2rem;
  border-top: 1px solid var(--border-color);
  color: #666;
}

/* 标题 */
h1 {
  font-size: 2.5rem;
  margin-bottom: 1rem;
  color: var(--primary-color);
  line-height: 1.3;
}

h2 {
  font-size: 1.8rem;
  margin: 2rem 0 1rem;
  color: var(--primary-color);
}

h3 {
  font-size: 1.3rem;
  margin: 1.5rem 0 0.8rem;
}

p {
  margin-bottom: 1rem;
}

/* 强调 */
.highlight {
  color: var(--accent-color);
  font-weight: bold;
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.8rem 1.5rem;
  background: var(--accent-color);
  color: white;
  text-decoration: none;
  border-radius: 6px;
  margin-top: 1rem;
  margin-right: 0.8rem;
  transition: all 0.3s;
  font-weight: 500;
}

.btn:hover {
  background: #e8830f;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(247, 147, 26, 0.3);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--accent-color);
  color: var(--accent-color);
}

.btn-outline:hover {
  background: var(--accent-color);
  color: white;
  transform: translateY(-2px);
  box-shadow: 0 4px 8px rgba(247, 147, 26, 0.2);
}

/* 卡片 */
.card {
  background: var(--light-gray);
  padding: 1.5rem;
  border-radius: 12px;
  margin-bottom: 1rem;
  border: 1px solid transparent;
  transition: all 0.3s;
}

.card:hover {
  border-color: var(--accent-color);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

/* 列表 */
ul.bullet-list {
  margin-left: 1.5rem;
  margin-bottom: 1rem;
}

ul.bullet-list li {
  margin-bottom: 0.5rem;
}

/* 分隔线 */
hr {
  border: none;
  border-top: 2px solid var(--border-color);
  margin: 2rem 0;
}

/* 响应式 */
@media (max-width: 768px) {
  nav {
    padding: 0.8rem 1rem;
  }

  nav .logo {
    font-size: 1.2rem;
  }

  .hamburger {
    display: flex;
  }

  nav ul {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--nav-bg);
    flex-direction: column;
    padding: 1rem;
    gap: 0;
    border-bottom: 1px solid var(--border-color);
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  }

  nav ul.show {
    display: flex;
  }

  nav ul li {
    width: 100%;
  }

  nav ul li a {
    padding: 0.8rem 1rem;
    border-radius: 6px;
  }

  nav ul li a:hover {
    background: var(--light-gray);
  }

  h1 {
    font-size: 2rem;
  }

  h2 {
    font-size: 1.5rem;
  }

  main {
    margin-top: 100px;
    padding: 0 1rem;
  }

  .btn {
    width: 100%;
    margin-right: 0;
    margin-bottom: 0.5rem;
    justify-content: center;
  }
}

/* 快速链接区域 */
.quick-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  margin: 2rem 0;
  padding: 1.5rem;
  background: var(--light-gray);
  border-radius: 12px;
}

.quick-link {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding: 1rem;
  background: white;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-color);
  transition: all 0.3s;
  border: 2px solid transparent;
}

.quick-link:hover {
  border-color: var(--accent-color);
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
}

.quick-link .icon {
  font-size: 1.5rem;
}

.quick-link .title {
  font-weight: 600;
  color: var(--primary-color);
}

.quick-link .desc {
  font-size: 0.85rem;
  color: #666;
}

/* 面包屑导航 */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
  font-size: 0.9rem;
  color: #666;
}

.breadcrumb a {
  color: var(--accent-color);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

.breadcrumb span {
  color: #999;
}

/* 返回顶部按钮 */
.back-to-top {
  position: fixed;
  bottom: 2rem;
  right: 2rem;
  width: 45px;
  height: 45px;
  background: var(--accent-color);
  color: white;
  border: none;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  box-shadow: 0 4px 12px rgba(247, 147, 26, 0.4);
  transition: all 0.3s;
  z-index: 100;
}

.back-to-top:hover {
  background: #e8830f;
  transform: translateY(-2px);
}

.back-to-top.hidden {
  display: none;
}

@media (max-width: 768px) {
  .back-to-top {
    bottom: 1rem;
    right: 1rem;
    width: 40px;
    height: 40px;
  }
}