:root {
      --theme: #0B3D91;
      --theme-dark: #072d6d;
      --theme-soft: #eaf1fb;
      --green: #287a4b;
      --green-dark: #195b36;
      --wood: #b9834d;
      --wood-light: #f2e4d2;
      --ink: #172033;
      --muted: #657084;
      --line: #dce2ea;
      --surface: #ffffff;
      --page: #f5f7fa;
      --shadow: 0 14px 35px rgba(23, 32, 51, 0.1);
      --container: 1200px;
    }

    * {
      box-sizing: border-box;
    }

    html {
      scroll-behavior: smooth;
    }

    body {
      margin: 0;
      color: var(--ink);
      background: var(--page);
      font-family: "Microsoft YaHei", "PingFang SC", Arial, sans-serif;
      line-height: 1.65;
    }

    body,
    button,
    input {
      font: inherit;
    }

    img {
      display: block;
      max-width: 100%;
    }

    a {
      color: inherit;
      text-decoration: none;
    }

    button {
      color: inherit;
    }

    .container {
      width: min(calc(100% - 40px), var(--container));
      margin: 0 auto;
    }

    .topbar {
      color: #eaf1fb;
      background: #10213b;
      font-size: 13px;
    }

    .topbar .container {
      min-height: 38px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 24px;
    }

    .topbar a {
      color: #ffffff;
    }

    .header {
      position: relative;
      z-index: 50;
      background: rgba(255, 255, 255, 0.98);
      border-bottom: 1px solid var(--line);
    }

    .header-inner {
      min-height: 76px;
      display: flex;
      align-items: center;
      gap: 24px;
    }

    .logo {
      flex: 0 0 auto;
      display: inline-flex;
      align-items: center;
      gap: 10px;
      color: var(--theme);
      font-size: 19px;
      font-weight: 800;
    }

    .logo img {
      width: 42px;
      height: 42px;
      object-fit: contain;
      border-radius: 6px;
    }

    .main-nav {
      min-width: 0;
      flex: 1 1 auto;
    }

    .nav-list {
      height: 76px;
      display: flex;
      align-items: stretch;
      justify-content: center;
      gap: 2px;
      margin: 0;
      padding: 0;
      list-style: none;
    }

    .nav-list > li {
      position: relative;
      display: flex;
      align-items: stretch;
    }

    .nav-link {
      display: flex;
      align-items: center;
      padding: 0 13px;
      color: #273247;
      font-size: 15px;
      font-weight: 700;
      white-space: nowrap;
      border-bottom: 3px solid transparent;
    }

    .nav-link:hover,
    .nav-list > li:focus-within > .nav-link {
      color: var(--theme);
      border-bottom-color: var(--theme);
    }

    .has-arrow::after {
      width: 6px;
      height: 6px;
      margin: -3px 0 0 8px;
      content: "";
      border-right: 1.5px solid currentColor;
      border-bottom: 1.5px solid currentColor;
      transform: rotate(45deg);
    }

    .dropdown-panel,
    .mega-menu {
      position: absolute;
      top: 100%;
      left: 50%;
      z-index: 60;
      visibility: hidden;
      opacity: 0;
      background: #ffffff;
      border: 1px solid var(--line);
      box-shadow: var(--shadow);
      transform: translate(-50%, 8px);
      transition: opacity 0.18s ease, transform 0.18s ease, visibility 0.18s;
    }

    .dropdown-panel {
      width: 300px;
      padding: 18px;
      border-radius: 0 0 6px 6px;
    }

    .mega-menu {
      width: min(760px, calc(100vw - 40px));
      padding: 22px;
      border-radius: 0 0 6px 6px;
    }

    .nav-list > li:hover > .dropdown-panel,
    .nav-list > li:hover > .mega-menu,
    .nav-list > li:focus-within > .dropdown-panel,
    .nav-list > li:focus-within > .mega-menu {
      visibility: visible;
      opacity: 1;
      transform: translate(-50%, 0);
    }

    .drop-title,
    .mega-title {
      margin: 0 0 12px;
      color: var(--theme);
      font-size: 13px;
      font-weight: 800;
    }

    .drop-item {
      display: block;
      min-width: 0;
      padding: 9px 10px;
      color: #334058;
      font-size: 14px;
      border-radius: 4px;
    }

    .drop-item:hover {
      color: var(--theme);
      background: var(--theme-soft);
    }

    .mega-grid {
      display: grid;
      grid-template-columns: repeat(2, minmax(0, 1fr));
      gap: 10px;
    }

    .mega-card {
      min-width: 0;
      display: flex;
      align-items: center;
      gap: 12px;
      padding: 10px;
      border: 1px solid #e6eaf0;
      border-radius: 6px;
    }

    .mega-card:hover {
      border-color: #9eb8df;
      background: #f8fbff;
    }

    .mega-card img {
      flex: 0 0 50px;
      width: 50px;
      height: 44px;
      object-fit: cover;
      background: #eef2f7;
      border-radius: 4px;
    }

    .mega-card > span {
      min-width: 0;
      display: grid;
      gap: 2px;
    }

    .mega-card strong,
    .mega-card span span {
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }

    .mega-card strong {
      color: #1f2b40;
      font-size: 14px;
    }

    .mega-card span span {
      color: var(--muted);
      font-size: 12px;
    }

    .mega-footer {
      display: block;
      margin-top: 14px;
      padding: 10px 12px;
      color: #ffffff;
      background: var(--theme);
      text-align: center;
      font-size: 14px;
      font-weight: 700;
      border-radius: 4px;
    }

    .mega-footer:hover {
      background: var(--theme-dark);
    }

    .header-btns {
      flex: 0 0 auto;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .member-btn,
    .open-btn {
      min-height: 38px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 0 14px;
      font-size: 14px;
      font-weight: 700;
      border-radius: 4px;
    }

    .member-btn {
      color: var(--theme);
      border: 1px solid #9eb8df;
    }

    .open-btn {
      color: #ffffff;
      background: var(--theme);
      border: 1px solid var(--theme);
    }

    .hamburger {
      width: 42px;
      height: 42px;
      display: none;
      padding: 9px;
      cursor: pointer;
      background: #ffffff;
      border: 1px solid var(--line);
      border-radius: 4px;
    }

    .hamburger span {
      width: 22px;
      height: 2px;
      display: block;
      margin: 4px 0;
      background: var(--ink);
      transition: transform 0.2s ease, opacity 0.2s ease;
    }

    .hamburger.active span:nth-child(1) {
      transform: translateY(6px) rotate(45deg);
    }

    .hamburger.active span:nth-child(2) {
      opacity: 0;
    }

    .hamburger.active span:nth-child(3) {
      transform: translateY(-6px) rotate(-45deg);
    }

    .drawer-overlay {
      position: fixed;
      inset: 0;
      z-index: 80;
      visibility: hidden;
      opacity: 0;
      background: rgba(10, 18, 31, 0.58);
      transition: opacity 0.2s ease, visibility 0.2s;
    }

    .drawer-overlay.open {
      visibility: visible;
      opacity: 1;
    }

    .mobile-drawer {
      position: fixed;
      top: 0;
      right: 0;
      z-index: 90;
      width: min(390px, 92vw);
      height: 100vh;
      overflow-y: auto;
      background: #ffffff;
      box-shadow: -18px 0 40px rgba(9, 20, 39, 0.2);
      transform: translateX(105%);
      transition: transform 0.25s ease;
    }

    .mobile-drawer.open {
      transform: translateX(0);
    }

    .drawer-head {
      min-height: 70px;
      display: flex;
      align-items: center;
      gap: 12px;
      padding: 14px 18px;
      color: #ffffff;
      background: var(--theme);
    }

    .drawer-head > span {
      min-width: 0;
      flex: 1 1 auto;
      font-weight: 700;
    }

    .drawer-head > a {
      padding: 7px 11px;
      color: var(--theme);
      background: #ffffff;
      font-size: 13px;
      font-weight: 800;
      border-radius: 4px;
    }

    .drawer-close {
      width: 36px;
      height: 36px;
      padding: 0;
      color: #ffffff;
      cursor: pointer;
      background: transparent;
      border: 0;
      font-size: 28px;
      line-height: 1;
    }

    .drawer-menu {
      padding: 12px 18px 28px;
    }

    .drawer-link,
    .drawer-toggle {
      width: 100%;
      min-height: 48px;
      display: flex;
      align-items: center;
      padding: 10px 4px;
      cursor: pointer;
      background: transparent;
      border: 0;
      border-bottom: 1px solid #e7eaf0;
      text-align: left;
      font-weight: 700;
    }

    .drawer-toggle {
      justify-content: space-between;
    }

    .drawer-toggle::after {
      width: 8px;
      height: 8px;
      content: "";
      border-right: 2px solid var(--theme);
      border-bottom: 2px solid var(--theme);
      transform: rotate(45deg);
      transition: transform 0.2s ease;
    }

    .drawer-toggle.active::after {
      transform: rotate(225deg);
    }

    .drawer-submenu {
      max-height: 0;
      overflow: hidden;
      background: #f6f8fb;
      transition: max-height 0.25s ease;
    }

    .drawer-submenu.open {
      max-height: 700px;
    }

    .drawer-submenu a {
      display: block;
      padding: 9px 14px;
      color: #47536a;
      font-size: 14px;
      border-bottom: 1px solid #e7eaf0;
    }

    .video-page {
      min-height: 640px;
    }

    .video-page .video-heading {
      padding: 58px 0 46px;
      color: #ffffff;
      background:
        linear-gradient(rgba(7, 45, 109, 0.93), rgba(11, 61, 145, 0.88)),
        radial-gradient(circle at 16% 25%, #4f8bd8 0, transparent 28%);
    }

    .video-page .heading-kicker {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      margin: 0 0 10px;
      color: #d8e7fb;
      font-size: 14px;
      font-weight: 800;
    }

    .video-page .heading-kicker::before {
      width: 28px;
      height: 3px;
      content: "";
      background: #ffffff;
    }

    .video-page .video-heading h1 {
      max-width: 800px;
      margin: 0;
      font-size: clamp(31px, 5vw, 52px);
      line-height: 1.18;
      letter-spacing: 0;
    }

    .video-page .video-heading p {
      max-width: 760px;
      margin: 14px 0 0;
      color: #e4edfa;
      font-size: 16px;
    }

    .video-page .category-strip {
      margin-top: -22px;
      position: relative;
      z-index: 2;
    }

    .video-page .category-inner {
      display: flex;
      align-items: center;
      gap: 10px;
      padding: 13px;
      overflow-x: auto;
      background: #ffffff;
      border: 1px solid var(--line);
      box-shadow: 0 10px 28px rgba(20, 37, 67, 0.1);
      border-radius: 6px;
      scrollbar-width: thin;
    }

    .video-page .category-label {
      flex: 0 0 auto;
      padding: 8px 10px;
      color: var(--green-dark);
      font-size: 13px;
      font-weight: 800;
    }

    .video-page .category-chip {
      flex: 0 0 auto;
      padding: 8px 13px;
      color: #354159;
      background: #f5f7fa;
      border: 1px solid #e1e6ed;
      border-radius: 4px;
      font-size: 14px;
      font-weight: 700;
    }

    .video-page .category-chip:hover {
      color: #ffffff;
      background: var(--theme);
      border-color: var(--theme);
    }

    .video-page .video-library {
      padding: 54px 0 72px;
    }

    .video-page .library-head {
      display: flex;
      align-items: end;
      justify-content: space-between;
      gap: 24px;
      margin-bottom: 24px;
    }

    .video-page .library-head h2 {
      margin: 0;
      color: #1b2940;
      font-size: 28px;
      line-height: 1.3;
    }

    .video-page .library-head p {
      max-width: 610px;
      margin: 7px 0 0;
      color: var(--muted);
    }

    .video-page .library-mark {
      flex: 0 0 auto;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      color: var(--green-dark);
      font-size: 13px;
      font-weight: 800;
    }

    .video-page .library-mark::before {
      width: 9px;
      height: 9px;
      content: "";
      background: var(--green);
      border-radius: 50%;
      box-shadow: 0 0 0 5px rgba(40, 122, 75, 0.13);
    }

    .video-page .video-grid {
      display: grid;
      grid-template-columns: repeat(3, minmax(0, 1fr));
      gap: 22px;
    }

    .video-page .video-card {
      min-width: 0;
      overflow: hidden;
      background: var(--surface);
      border: 1px solid var(--line);
      border-radius: 6px;
      transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s ease;
    }

    .video-page .video-card:hover {
      border-color: #a7bddd;
      box-shadow: var(--shadow);
      transform: translateY(-4px);
    }

    .video-page .video-cover {
      position: relative;
      overflow: hidden;
      aspect-ratio: 16 / 9;
      background: #dfe6ef;
    }

    .video-page .video-cover img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.35s ease;
    }

    .video-page .video-card:hover .video-cover img {
      transform: scale(1.035);
    }

    .video-page .play-icon {
      position: absolute;
      inset: 50% auto auto 50%;
      width: 48px;
      height: 48px;
      background: rgba(255, 255, 255, 0.94);
      border-radius: 50%;
      box-shadow: 0 6px 20px rgba(5, 16, 34, 0.24);
      transform: translate(-50%, -50%);
    }

    .video-page .play-icon::after {
      position: absolute;
      top: 50%;
      left: 52%;
      content: "";
      border-top: 8px solid transparent;
      border-bottom: 8px solid transparent;
      border-left: 12px solid var(--theme);
      transform: translate(-40%, -50%);
    }

    .video-page .video-duration {
      position: absolute;
      right: 10px;
      bottom: 10px;
      padding: 3px 7px;
      color: #ffffff;
      background: rgba(8, 15, 27, 0.82);
      font-size: 12px;
      font-weight: 700;
      border-radius: 3px;
    }

    .video-page .video-card-body {
      min-width: 0;
      padding: 18px;
    }

    .video-page .video-category {
      display: inline-block;
      margin-bottom: 8px;
      color: var(--green-dark);
      font-size: 12px;
      font-weight: 800;
    }

    .video-page .video-card h2 {
      min-height: 50px;
      margin: 0;
      color: #19263b;
      font-size: 18px;
      line-height: 1.4;
    }

    .video-page .video-summary {
      min-height: 72px;
      margin: 10px 0 16px;
      overflow: hidden;
      color: var(--muted);
      font-size: 14px;
      display: -webkit-box;
      -webkit-box-orient: vertical;
      -webkit-line-clamp: 3;
    }

    .video-page .video-meta {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 12px;
      padding-top: 13px;
      color: #7b8495;
      font-size: 12px;
      border-top: 1px solid #e7eaf0;
    }

    .video-page .watch-link {
      color: var(--theme);
      font-weight: 800;
    }

    .video-page .pagination {
      display: flex;
      flex-wrap: wrap;
      justify-content: center;
      gap: 8px;
      margin-top: 38px;
    }

    .video-page .pagination a {
      min-width: 40px;
      min-height: 40px;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 7px 12px;
      color: #334058;
      background: #ffffff;
      border: 1px solid #d9dfe8;
      border-radius: 4px;
      font-size: 14px;
      font-weight: 700;
    }

    .video-page .pagination a:hover,
    .video-page .pagination a.active,
    .video-page .pagination a.current {
      color: #ffffff;
      background: var(--theme);
      border-color: var(--theme);
    }

    .video-page .learning-band {
      padding: 0 0 72px;
    }

    .video-page .learning-inner {
      display: grid;
      grid-template-columns: repeat(3, minmax(0, 1fr));
      overflow: hidden;
      background: #ffffff;
      border: 1px solid #ddd5ca;
      border-radius: 6px;
    }

    .video-page .learning-step {
      position: relative;
      min-width: 0;
      padding: 26px;
    }

    .video-page .learning-step + .learning-step {
      border-left: 1px solid #ddd5ca;
    }

    .video-page .learning-step span {
      display: block;
      margin-bottom: 7px;
      color: var(--green-dark);
      font-size: 12px;
      font-weight: 800;
    }

    .video-page .learning-step strong {
      display: block;
      margin-bottom: 6px;
      color: #273045;
      font-size: 18px;
    }

    .video-page .learning-step p {
      margin: 0;
      color: var(--muted);
      font-size: 14px;
    }

    .video-page .learning-step:nth-child(1) {
      background: var(--wood-light);
    }

    .video-page .learning-step:nth-child(2) {
      background: #edf6f0;
    }

    .video-page .learning-step:nth-child(3) {
      background: #ffffff;
    }

    .footer {
      color: #cbd4e2;
      background: #101a2b;
    }

    .footer .container {
      padding-top: 54px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 1.5fr 1fr 1fr 1.1fr;
      gap: 38px;
      padding-bottom: 38px;
    }

    .footer-brand {
      margin-bottom: 12px;
      color: #ffffff;
      font-size: 22px;
      font-weight: 800;
    }

    .footer h3 {
      margin: 0 0 14px;
      color: #ffffff;
      font-size: 15px;
    }

    .footer p {
      margin: 0 0 10px;
      font-size: 14px;
    }

    .footer-grid > div > a {
      display: block;
      width: fit-content;
      margin-bottom: 9px;
      color: #cbd4e2;
      font-size: 14px;
    }

    .footer-grid > div > a:hover {
      color: #ffffff;
    }

    .footer-social {
      margin-top: 18px;
    }

    .footer-bottom {
      padding: 19px 0 23px;
      color: #99a6b9;
      font-size: 13px;
      text-align: center;
      border-top: 1px solid #2a3547;
    }

    @media (max-width: 1120px) {
      .main-nav {
        display: none;
      }

      .hamburger {
        display: block;
      }

      .header-inner {
        min-height: 68px;
      }

      .logo {
        margin-right: auto;
      }
    }

    @media (max-width: 900px) {
      .video-page .video-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
      }

      .footer-grid {
        grid-template-columns: repeat(2, minmax(0, 1fr));
      }
    }

    @media (max-width: 680px) {
      .container {
        width: min(calc(100% - 28px), var(--container));
      }

      .topbar .container {
        min-height: 34px;
        justify-content: center;
      }

      .topbar .contact {
        display: none;
      }

      .header-inner {
        gap: 10px;
      }

      .logo span {
        max-width: 145px;
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
      }

      .member-btn,
      .open-btn {
        display: none;
      }

      .video-page .video-heading {
        padding: 42px 0 38px;
      }

      .video-page .video-heading h1 {
        font-size: 32px;
      }

      .video-page .category-strip {
        margin-top: -16px;
      }

      .video-page .video-library {
        padding: 42px 0 54px;
      }

      .video-page .library-head {
        display: block;
      }

      .video-page .library-mark {
        margin-top: 14px;
      }

      .video-page .video-grid {
        grid-template-columns: 1fr;
      }

      .video-page .video-card h2,
      .video-page .video-summary {
        min-height: 0;
      }

      .video-page .learning-inner {
        grid-template-columns: 1fr;
      }

      .video-page .learning-step + .learning-step {
        border-top: 1px solid #ddd5ca;
        border-left: 0;
      }

      .footer-grid {
        grid-template-columns: 1fr;
        gap: 28px;
      }
    }