/************************************************/
/* style-science-year-optimized.css (整合版本)  */
/************************************************/

/* ============ [基础重置] ============ */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
html, body {
  font-family: "微软雅黑", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.6;
  color: #333;
  background-color: #f9f9f9;
}
/* 容器通用 */
.section-container, .footer-container {
  width: 90%;
  max-width: 1920px;
  margin: 0 auto;
  padding: 10px 0;
}
/* ============ [头部 - 来自目标页面 + 旧页面合并] ============ */
.header {
  background-color: #004080;
  color: #fff;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  padding: 10px 0;
  z-index: 1000;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease-in-out;
}
.header--hidden {
  transform: translateY(-100%);
}
/* 头部容器：左右Logo + 中间标题导航 */
.header-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
}
.header-left-logo img, .header-right-logo img {
  max-width: 60px;
  height: auto;
  padding: 5px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  border-radius: 8px;
  transition: transform 0.3s;
}
.header-left-logo img:hover, .header-right-logo img:hover {
  transform: translateY(-2px);
}
/* 中间部分：标题 + 导航 */
.header-center-block {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex: 1;
  text-align: center;
}
.header-top h1 {
  font-size: 24px;
  font-weight: 700;
  text-align: center;
  margin: 5px 0;
  color: #fff;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 100%;
  transition: transform 0.3s;
}
.header-top h1:hover {
  transform: scale(1.02);
}
/* ============ [导航栏与汉堡按钮样式 - 来自目标页面] ============ */
.navbar {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 100%;
}
.menu-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
  background: none;
  border: none;
  padding: 10px;
}
.menu-toggle:focus {
  outline: none;
}
.menu-toggle .bar {
  height: 3px;
  width: 25px;
  background-color: #fff;
  margin: 4px 0;
  transition: all 0.3s ease;
}
/* 点击时的“X”动画 */
.menu-toggle.open .bar:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}
.menu-toggle.open .bar:nth-child(2) {
  opacity: 0;
}
.menu-toggle.open .bar:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}
/* 导航列表：默认在大屏显示为横向 */
.nav-list {
  list-style: none;
  display: flex;
  justify-content: center;
  gap: 20px;
  width: 100%;
}
.nav-list li {
  position: relative;
}
.nav-list li a {
  color: #fff;
  text-decoration: none;
  font-weight: 500;
  padding: 10px 15px;
  display: block;
  transition: color 0.3s ease, background-color 0.3s ease, text-decoration 0.3s ease;
}
.nav-list li a:hover {
  color: #ffcc00;
  background-color: rgba(255, 204, 0, 0.2);
  text-decoration: underline;
}
/* ============ [旧页面主体部分样式 - 保留或微调] ============ */
main {
  margin-top: 120px; /* 给header留出固定空间 */
  position: relative; /* 为分页按钮定位提供参考 */
}
/* 章节板块 */
.section {
  position: relative;
  padding: 30px 20px;
  margin-bottom: 15px;
  border-radius: 8px;
  background: #fff;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.section:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 10px rgba(0, 0, 0, 0.15);
}
.section h2 {
  margin-bottom: 15px;
  color: #004080;
  font-size: 24px;
  position: relative;
}
.section h2::after {
  content: '';
  width: 40px;
  height: 3px;
  background-color: #ffcc00;
  position: absolute;
  bottom: -8px;
  left: 0;
}
/* 论文索引卡片 */
.index-group {
  display: flex;
  flex-wrap: wrap;
  gap: 40px;
  margin-top: 20px;
}
.index-item {
  flex: 1 1 400px;
  background: #f0f0f0;
  border-radius: 8px;
  padding: 20px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s, box-shadow 0.3s;
}
.index-item:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 10px rgba(0, 0, 0, 0.15);
}
.index-item h3 {
  margin: 0 0 15px;
  color: #004080;
  font-size: 20px;
  border-bottom: 1px solid #ccc;
  padding-bottom: 5px;
}
.index-item h3 a {
  text-decoration: none;
  color: #004080;
}
.index-item h3 a:hover {
  text-decoration: underline;
}
.tocimg {
    display: block;
    height: auto;
    max-width: 300px;
}
.construction {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
/* 分页按钮 */
.pagination {
  display: flex;
  gap: 8px;
  margin-top: 20px;
  justify-content: center;
  align-items: center;
}
.pagination-button {
  display: inline-block;
  padding: 6px 12px;
  background: #f0f0f0;
  color: #333;
  text-decoration: none;
  border-radius: 4px;
  transition: 0.3s;
}
.pagination-button:hover {
  background: #004080;
  color: #fff;
}
.pagination-button.active {
  background: #004080;
  color: #fff;
}
.switch {
  float: right;
}
/* ============ [页脚] ============ */
footer {
  background-color: #004080;
  color: #fff;
  text-align: center;
  padding: 10px 0;
  position: relative;
  margin-top: 30px;
}
/* ============ [回到顶部按钮] ============ */
.back-to-top {
  position: fixed;
  bottom: 20px;
  right: 20px;
  display: none;
  background: #004080;
  color: #fff;
  border: none;
  border-radius: 50%;
  width: 40px;
  height: 40px;
  cursor: pointer;
  font-size: 18px;
  text-align: center;
  line-height: 40px;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.2);
  transition: background 0.3s;
}
.back-to-top:hover {
  background: #003060;
}
/* ============ [响应式 - 与目标页面相同] ============ */
@media (max-width: 992px) {
  .header-left-logo, .header-right-logo {
    display: none;
  }
  .header-container {
    justify-content: center;
  }
  .menu-toggle {
    display: flex;
    margin: 0 auto;
    align-items: center;
  }
  .nav-list {
    display: none;
    flex-direction: column;
    background-color: #004080;
    width: 100%;
  }
  .nav-list.active {
    display: flex;
  }
  .nav-list li a {
    padding: 6px 0;
    font-size: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    height: 20px;
  }
  .nav-list li {
    text-align: center;
    border-top: 1px solid #0059b3;
  }
  .nav-list li:first-child {
    border-top: none;
  }
}
@media (max-width: 480px) {
  .header-top h1 {
    font-size: 20px;
  }
  .section {
    padding: 20px 10px;
  }
  .index-item {
    padding: 15px;
  }
  .index-item h3 {
    font-size: 18px;
  }
}

/* ============ [新增：分页导航按钮] ============ */

/* 按钮通用样式 */
.page-nav-button {
  position: fixed; /* 固定定位，不随滚动 */
  top: 50%;
  transform: translateY(-50%);
  width: 90px; /* 扩大为原来的3倍 */
  height: 90px; /* 扩大为原来的3倍 */
  cursor: pointer;
  border: none;
  background: transparent;
  padding: 0;
  z-index: 600;
}

/* 去除按钮默认样式 */
.page-nav-button:focus {
  outline: none;
}

/* 左箭头按钮（上一页） */
.prev-page-button::before {
  content: '';
  display: inline-block;
  width: 0;
  height: 0;
  border-top: 24px solid transparent; /* 扩大为原来的3倍 */
  border-bottom: 24px solid transparent; /* 扩大为原来的3倍 */
  border-right: 36px solid #004080; /* 与页面主色一致，扩大为原来的3倍 */
}

/* 右箭头按钮（下一页） */
.next-page-button::before {
  content: '';
  display: inline-block;
  width: 0;
  height: 0;
  border-top: 24px solid transparent; /* 扩大为原来的3倍 */
  border-bottom: 24px solid transparent; /* 扩大为原来的3倍 */
  border-left: 36px solid #004080; /* 与页面主色一致，扩大为原来的3倍 */
}

/* 按钮颜色与页面风格匹配 */
.page-nav-button:hover::before {
  border-left-color: #0059b3; /* 深色表示悬停 */
  border-right-color: #0059b3;
}

/* 左按钮定位 */
.prev-page-button {
  left: 1%;
}

/* 右按钮定位 */
.next-page-button {
  right: 1%;
}

/* 响应式调整 */
@media (max-width: 768px) {
  .page-nav-button {
    width: 75px; /* 适当缩小 */
    height: 75px;
  }

  .prev-page-button::before,
  .next-page-button::before {
    border-top: 18px solid transparent; /* 6px * 3 */
    border-bottom: 18px solid transparent;
  }

  .prev-page-button::before {
    b