@charset "utf-8";
/* CSS Document */
 * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  body {
    font-family: '微软雅黑', 'PingFang SC', system-ui, sans-serif;
    background-color: #f4f7fc;
    color: #1e2f4e;
    line-height: 1.6;
  }
  a {
    text-decoration: none;
    transition: all 0.25s ease;
  }
  .wrapper {
    width: 1200px;
    max-width: 90%;
    margin: 0 auto;
  }
  .cls {
    clear: both;
  }
  .bigdiv {
    width: 100%;
  }
  .px15 {
    margin-top: 15px;
  }

  /* ========== 导航栏  ========== */
  .navbg {
    background: linear-gradient(145deg, #3d7ca8, #5095c7); /* 原 #1e4b6e → 更亮 */
    box-shadow: 0 4px 12px rgba(28, 100, 150, 0.25);
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 100;
    border-bottom: 1px solid rgba(255,255,255,0.3);
  }
  .navbar {
    display: flex;
    justify-content: center;
    width: 100%;
  }
  .navbar ul {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
  }
  .navbar ul li {
    position: relative;
  }
  .navbar ul li a {
    display: block;
    padding: 14px 28px;
    color: #ffffff;
    font-weight: 500;
    letter-spacing: 0.5px;
    font-size: 16px;
    border-bottom: 2px solid transparent;
    white-space: nowrap;
  }
  .navbar ul li a i {
    margin-right: 6px;
    font-size: 15px;
    color: #ffe484;
  }
  .navbar ul li a:hover {
    border-bottom-color: #ffe484;
    color: #ffffff;
    background-color: transparent;
  }
  
  /* 下拉菜单  */
  .navbar ul li ul {
    position: absolute;
    top: 100%;
    left: 0;
    background: linear-gradient(145deg, #5095c7, #60a5d9); /* 更亮 */
    border-radius: 0 0 8px 8px;
    box-shadow: 0 10px 20px -5px rgba(30, 90, 140, 0.35);
    display: none;
    min-width: 180px;
    padding: 5px 0;
  }
  .navbar ul li:hover ul {
    display: block;
  }
  .navbar ul li ul li {
    width: 100%;
  }
  .navbar ul li ul li a {
    padding: 10px 20px;
    border-bottom: 1px solid rgba(255,255,255,0.15);
    font-size: 14px;
    white-space: nowrap;
  }
  .navbar ul li ul li a:hover {
    background: #70b5e6;
    border-bottom-color: transparent;
  }
  .navbar ul li ul li:last-child a {
    border-bottom: none;
  }

  /* ========== 顶部留空补偿 ========== */
  .tops50 {
    margin-top: 58px;
  }

  /* ========== 轮播图 ========== */
  .banner {
    width: 100%;
    background-color: #f0f7ff;
    border-radius: 20px;
    overflow: hidden;
  }
  .focusBox {
    position: relative;
    width: 100%;
    height: auto;
    min-height: 380px;
    margin: 0 auto;
  }
  .focusBox .pic {
    position: relative;
    width: 100%;
    height: auto;
  }
  .focusBox .pic li {
    display: none;
    width: 100%;
    height: auto;
  }
  .focusBox .pic li:first-child {
    display: block;
  }
  .focusBox .pic img {
    width: 100%;
    height: auto;
    display: block;
    object-fit: contain;
    background-color: #e6f0fa;
  }
  
  /* 控制点 */
  .focusBox .hd {
    position: absolute;
    bottom: 20px;
    left: 0;
    width: 100%;
    text-align: center;
    z-index: 10;
  }
  .focusBox .hd li {
    display: inline-block;
    width: 12px;
    height: 12px;
    margin: 0 6px;
    background: rgba(255,255,255,0.6);
    border-radius: 50%;
    cursor: pointer;
    text-indent: -9999px;
    border: 1px solid rgba(0,0,0,0.2);
  }
  .focusBox .hd li.on {
    background: #ffe484;
    border-color: #ffe484;
  }
  
  /* 箭头 */
  .focusBox .prev, .focusBox .next {
    position: absolute;
    top: 50%;
    width: 44px;
    height: 44px;
    margin-top: -22px;
    background: rgba(45, 115, 170, 0.8);  /* 半透明 */
    border-radius: 50%;
    color: white;
    font-size: 36px;
    line-height: 44px;
    text-align: center;
    cursor: pointer;
    z-index: 11;
    transition: 0.2s;
    text-indent: 0;
    font-weight: 300;
    text-decoration: none;
  }
  .focusBox .prev {
    left: 20px;
  }
  .focusBox .next {
    right: 20px;
  }
  .focusBox .prev:hover, .focusBox .next:hover {
    background: #ffe484;
    color: #1e4b6e;
  }

  /* ========== 侧边栏 ========== */
  .main_content {
    display: flex;
    flex-wrap: wrap;
    background-color: transparent;
    gap: 30px;
  }
  .siderleft {
    width: 280px;
    background: transparent;
  }
  .siderleft h2 {
    background: white;
    color: #0a2a44;
    font-size: 22px;
    font-weight: 600;
    padding: 18px 15px;
    margin: 0;
    border-radius: 16px 16px 0 0;
    text-align: center;
    box-shadow: 0 -5px 15px rgba(0,0,0,0.02);
    line-height: 1.3;
  }
  .siderleft h2 span {
    display: block;
    font-size: 13px;
    font-weight: 400;
    color: #587a9f;
    margin-top: 6px;
  }
  .slider_nav {
    background: white;
    border-radius: 0 0 16px 16px;
    box-shadow: 0 15px 25px -10px rgba(0,30,60,0.12);
    overflow: hidden;
  }
  
  /* ===== 左侧菜单 ===== */
  /* 所有菜单项基础样式 */
  .slider_nav ul li a {
    display: flex;
    align-items: center;
    justify-content: flex-start;
    background: white;
    color: #1e3b5c;
    font-weight: 500;
    border-bottom: 1px solid #eaf0f6;
    transition: 0.2s;
    line-height: 1.5;
  }
  
  /* 一级菜单（课程概况、课程资源） */
  .slider_nav ul li .kc {
    background: #f8fbfe;
    color: #0f3b6a;
    font-weight: 700;
    font-size: 20px;              /* 从20px */
    border-left: 4px solid #ffb347;
    padding: 18px 15px 18px 45px;  /* 左内边距45px */
    justify-content: flex-start;
  }
  .slider_nav ul li .kc i {
    color: #2d89c6;
    width: 32px;                   /* 图标宽度增加 */
    font-size: 20px;               /* 图标调大 */
    margin-right: 12px;            /* 间距增加 */
  }
  
  /* 二级菜单  */
  .slider_nav ul li ul li a {
    background: #f9fcff;
    font-weight: 400;
    color: #2f4858;
    font-size: 17px;               
    padding: 14px 15px 14px 75px;   /* 左内边距 ， */
    line-height: 1.5;
  }
  .slider_nav ul li ul li a i {
    font-size: 14px;               /* 图标 */
    color: #3a7ca5;
    margin-right: 16px;             /* 间距增加 */
    width: 22px;                    /* 图标容器加宽 */
    text-align: center;
  }
  
  /* hover效果保持不变 */
  .slider_nav ul li a:hover {
    background: #e2effb;
    color: #0a2a44;
    border-left: 3px solid #2d89c6;
    transform: translateX(3px);
  }

  /* 课程核心模块卡片 */
  .core-modules {
    margin-top: 20px;
    background: white;
    border-radius: 16px;
    padding: 18px 15px;
    box-shadow: 0 8px 18px rgba(0,35,60,0.08);
  }
  .core-modules h3 {
    font-size: 18px;
    color: #0a2a44;
    margin-bottom: 15px;
    font-weight: 600;
    display: flex;
    align-items: center;
  }
  .core-modules h3 i {
    color: #2d89c6;
    margin-right: 10px;
  }
  .stats-grid {
    display: flex;
    justify-content: space-around;
    margin-bottom: 15px;
  }
  .stat-item {
    text-align: center;
  }
  .stat-number {
    font-size: 28px;
    font-weight: 700;
    color: #1e5b9e;
    line-height: 1.2;
  }
  .stat-label {
    font-size: 13px;
    color: #587a9f;
  }
  .module-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 10px;
  }
  .module-tag {
    background: #ecf5fb;
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 13px;
    color: #1e3b5c;
  }

  /* ========== 主内容区域 ========== */
  .main_right {
    flex: 1;
    min-width: 0;
    background: transparent;
  }
  .content {
    background: white;
    border-radius: 20px;
    box-shadow: 0 20px 35px -15px rgba(8,30,55,0.15);
    overflow: hidden;
    border: 1px solid rgba(255,255,255,0.7);
  }
  .title_cont {
    background: linear-gradient(95deg, #f0f7ff, white);
    padding: 12px 25px;
    border-bottom: 2px solid rgba(45,137,198,0.2);
  }
  .title_cont h1 {
    background: transparent;
    color: #0c2e51;
    font-size: 24px;
    font-weight: 650;
    margin: 0;
    display: flex;
    align-items: center;
  }
  .title_cont h1 i {
    color: #2d89c6;
    margin-right: 12px;
    font-size: 28px;
  }
  .contents {
    padding: 25px 30px;
    font-size: 15px;
    color: #2a3f5e;
    line-height: 1.8;
  }
  .contents p {
    margin-bottom: 18px;
    font-size: 15px;
  }
  /* 首字下沉效果 */
/*  .contents p:first-of-type::first-letter {
    font-size: 48px;
    font-weight: 600;
    float: left;
    padding: 8px 8px 0 0;
    color: #1e5b9e;
    line-height: 0.8;
    margin-right: 6px;
  }*/
  .contents img {
    max-width: 100%;
    height: auto;
    border-radius: 12px;
    box-shadow: 0 8px 16px -6px rgba(0,30,60,0.15);
    margin: 15px 0;
  }

  /* ========== 底部  ========== */
  .footerBG {
    background: linear-gradient(145deg, #3d7ca8, #5095c7);  /* 与导航一致 */
    margin-top: 40px;
    border-top: 1px solid #76b3e0; 
  }
  .footer {
    color: #f0f5fa;
    font-size: 14px;
    padding: 16px 20px;
    text-align: center;
    letter-spacing: 0.3px;
  }
  .footer span {
    display: inline-block;
    margin-top: 4px;
    font-size: 12px;
    opacity: 0.9;
    color: #ffe484;
  }

  @media (max-width: 1000px) {
    .siderleft {
      width: 100%;
    }
    .main_right {
      width: 100%;
    }
    .navbar ul {
      flex-wrap: wrap;
      justify-content: center;
    }
    .navbar ul li a {
      padding: 10px 16px;
      font-size: 15px;
    }
  }