/**
 * 默认主题样式文件
 * 经典蓝白配色，适合专业学术网站
 */

/* 全局样式与配色方案 - 默认主题 */
:root {
  --primary-color: #8B0000; /* 深红色作为主色 */
  --secondary-color: #5D4037; /* 深褐色 */
  --background-color: #F5F5F0; /* 米色背景 */
  --text-color: #3E2723; /* 深褐色文字 */
  --light-accent: #D7CCC8; /* 浅米色 */
  --white: #FFFFFF;
  --transition-duration: 0.3s;
  --border-radius: 4px;
  --box-shadow-light: 0 1px 3px rgba(0,0,0,0.1);
  --box-shadow-medium: 0 2px 5px rgba(0,0,0,0.1);
  --box-shadow-heavy: 0 8px 16px rgba(0,0,0,0.1);
}

/* 跳转链接样式 */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--primary-color);
  color: white;
  padding: 8px;
  text-decoration: none;
  border-radius: var(--border-radius);
  z-index: 1000;
  transition: top var(--transition-duration);
  font-weight: 600;
}

.skip-link:focus {
  top: 6px;
  outline: 2px solid var(--white);
}
#main-content {
  max-width: 1400px;
  margin: 1rem auto;
  padding: 0 5%;

}


/* 屏幕阅读器专用 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: 'Noto Sans SC', 'Microsoft YaHei', sans-serif;
}

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

/* 提高可访问性：焦点样式 */
a:focus,
button:focus,
input:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* 导航栏 - 重构为移动友好型 */
header {
  background-color: var(--white);
  box-shadow: var(--box-shadow-medium);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 5%;
  max-width: 1400px;
  margin: 0 auto;
  position: relative;
}

.logo {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--primary-color);
  text-decoration: none;
  order: 1;
  transition: color var(--transition-duration);
}

.logo:hover {
  color: var(--secondary-color);
}

.menu-toggle {
  display: block;
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  order: 2;
  color: var(--text-color);
  margin-left: auto;
  padding: 0.5rem;
  border-radius: var(--border-radius);
  transition: background-color var(--transition-duration);
}

.menu-toggle:hover {
  background-color: var(--light-accent);
}

.nav-links {
  display: flex;
  list-style: none;
  order: 4;
  width: 100%;
  flex-direction: column;
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-duration) ease-out;
  padding: 0;
  margin: 0;
}

.nav-links.active {
  max-height: 1000px;
  margin-top: 1rem;
}

.nav-links li {
  margin: 0.5rem 0;
  position: relative;
}

.nav-links a {
  color: var(--text-color);
  text-decoration: none;
  font-weight: 500;
  transition: color var(--transition-duration);
  display: block;
  padding: 0.5rem 0;
  border-radius: var(--border-radius);
}

.nav-links a:hover {
  color: var(--primary-color);
  background-color: rgba(139, 0, 0, 0.05);
}

/* 二级菜单样式 */
.has-submenu {
  position: relative;
}

.has-submenu > a {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.submenu-toggle {
  margin-left: 5px;
  display: inline-block;
  transition: transform var(--transition-duration);
  font-size: 1.2em;
  line-height: 1;
}

.submenu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background: var(--white);
  min-width: 200px;
  box-shadow: var(--box-shadow-heavy);
  z-index: 1000;
  list-style: none;
  padding: 0.5rem 0;
  margin: 0;
  border-radius: var(--border-radius);
}

.submenu li {
  margin: 0;
}

.submenu a {
  padding: 0.5rem 1rem;
  white-space: nowrap;
  color: var(--text-color);
  margin: 0;
}

.submenu a:hover {
  background: var(--light-accent);
  color: var(--primary-color);
}

/* 面包屑导航 */
.breadcrumb {
  padding: 0.5rem 2%;
  max-width: 1400px;
  margin: 0 auto 1rem;
  font-size: 0.9rem;
  background-color: var(--white);
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow-light);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  list-style: none;
  padding: 0;
  margin: 0;
}

.breadcrumb li {
  display: flex;
  align-items: center;
}

.breadcrumb li:not(:last-child)::after {
  content: '/';
  margin: 0 0.5rem;
  color: #999;
}

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

.breadcrumb a:hover {
  color: var(--primary-color);
}

/* 搜索栏优化 */
.search-bar {
  display: flex;
  order: 2;
  width: 100%;
  margin: 1rem 0 0 0;
  align-items: center;
  position: relative;
}

.search-bar input {
  padding: 0.7rem 1rem;
  border: 1px solid var(--light-accent);
  border-radius: var(--border-radius) 0 0 var(--border-radius);
  outline: none;
  flex-grow: 1;
  height: 42px;
  box-sizing: border-box;
  font-size: 1rem;
  transition: border-color var(--transition-duration);
}

.search-bar input:focus {
  border-color: var(--primary-color);
}

.search-bar button {
  background-color: var(--primary-color);
  color: white;
  border: none;
  padding: 0 1.5rem;
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
  cursor: pointer;
  height: 42px;
  font-size: 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 80px;
  transition: background-color var(--transition-duration);
}

.search-bar button:hover {
  background-color: var(--secondary-color);
}

/* 搜索建议框 */
.search-suggestions {
  position: absolute;
  top: 100%;
  left: 0;
  right: 80px;
  background: var(--white);
  border: 1px solid var(--light-accent);
  border-top: none;
  border-radius: 0 0 var(--border-radius) var(--border-radius);
  box-shadow: var(--box-shadow-medium);
  z-index: 1000;
  display: none;
  max-height: 300px;
  overflow-y: auto;
}

.search-suggestions.show {
  display: block;
}

.suggestion-item {
  padding: 0.75rem 1rem;
  cursor: pointer;
  transition: background-color var(--transition-duration);
  border-bottom: 1px solid #f0f0f0;
}

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

.suggestion-item:hover,
.suggestion-item.highlighted {
  background-color: var(--light-accent);
}

/* 移动端二级菜单样式 */
@media (max-width: 991px) {
  .submenu {
    position: static;
    box-shadow: none;
    display: none;
    padding-left: 1rem;
    background-color: rgba(0,0,0,0.05);
    border-radius: 0;
    animation: slideDown var(--transition-duration) ease-out;
  }

  .submenu a {
    padding: 0.5rem 0.5rem 0.5rem 1.5rem;
  }

  .has-submenu.active .submenu {
    display: block;
  }

  .has-submenu.active .submenu-toggle {
    transform: rotate(90deg);
  }
}

/* 页脚 */
footer {
  background-color: var(--secondary-color);
  color: var(--light-accent);
  padding: 2rem 5%;
  margin-top: 3rem;
}

.footer-content {
  max-width: 1400px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
}

.footer-column h3 {
  color: var(--white);
  margin-bottom: 1rem;
  font-size: 1.1rem;
}

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

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

.footer-column a {
  color: var(--light-accent);
  text-decoration: none;
  transition: color var(--transition-duration);
}

.footer-column a:hover {
  color: var(--white);
  text-decoration: underline;
}

.copyright {
  text-align: center;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.1);
  font-size: 0.9rem;
}

/* 桌面端样式 */
@media (min-width: 992px) {
  .has-submenu:hover .submenu,
  .has-submenu:focus-within .submenu {
    display: block;
    animation: fadeIn var(--transition-duration) ease-out;
  }

  .has-submenu:hover .submenu-toggle,
  .has-submenu:focus-within .submenu-toggle {
    transform: rotate(90deg);
  }

  .nav-links {
    display: flex;
    flex-direction: row;
    max-height: none;
    width: auto;
    order: 2;
    overflow: visible;
    flex-wrap: wrap; /* 允许菜单换行 */
  }

  .nav-links li {
    margin-left: 0.5rem;
    margin-bottom: 0;
  }

  .search-bar {
    order: 3;
    width: auto;
    margin: 0 0 0 1.5rem;
    min-width: 200px; /* 确保搜索框有最小宽度 */
  }

  .menu-toggle {
    display: none;
  }

  /* 当内容过多时，允许navbar换行 */
  .navbar {
    flex-wrap: wrap;
  }

  /* 搜索框在空间不足时移到下一行 */
  @media (max-width: 1200px) {
    .search-bar {
      order: 4;
      width: 100%;
      margin: 1rem 0 0 0;
    }
  }
}

/* 动画效果 */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes slideDown {
  from {
    max-height: 0;
  }
  to {
    max-height: 300px;
  }
}

/* 内容区域样式 */
article {
  background-color: var(--white);
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow-light);
}

.section-title {
  font-size: 1.5rem;
  margin-bottom: 1.5rem;
  margin-left: 1.5rem;
  color: var(--secondary-color);
  position: relative;
  padding-bottom: 0.5rem;
}

/* 加载状态 */
.loading {
  opacity: 0.6;
  pointer-events: none;
}



/* 高对比度支持 */
@media (prefers-contrast: high) {
  :root {
    --primary-color: #000000;
    --text-color: #000000;
    --background-color: #FFFFFF;
  }
}

/* 暗色主题支持 */
@media (prefers-color-scheme: dark) {
  :root {
    --primary-color: #FF6B6B;
    --secondary-color: #8D6E63;
    --background-color: #1A1A1A;
    --text-color: #E0E0E0;
    --light-accent: #424242;
    --white: #2D2D2D;
  }
}