* { margin: 0; padding: 0; box-sizing: border-box; }
    html, body {
      font-family: Arial, sans-serif;
      background: #111;
      color: #fff;
      scroll-behavior: smooth;
      overflow-x: hidden;
    }
    #bg-video {
      position: fixed;
      top: 0; left: 0;
      width: 100vw;
      height: 100vh;
      object-fit: cover;
      opacity: 0.25;
      z-index: -1;
    }
    .nav-text {
      position: fixed;
      top: 20px;
      left: 50%;
      transform: translateX(-50%);
      display: flex;
      gap: 20px;
      padding: 10px 30px;
      background: rgba(0,0,0,0.5);
      border-radius: 30px;
      z-index: 1000;
      backdrop-filter: blur(8px);
      white-space: nowrap;
      overflow-x: auto;
      max-width: 95vw;
    }
    .nav-text::-webkit-scrollbar { display: none; }
    .nav-text a {
      text-decoration: none;
      color: #ccc;
      font-weight: bold;
      font-size: 0.9rem;
      transition: 0.3s;
    }
    .nav-text a.active,
    .nav-text a:hover {
      color: #00ffff;
    }
    .dot-nav {
      display: none;
      position: fixed;
      top: 50%;
      right: 20px;
      transform: translateY(-50%);
      z-index: 1000;
      flex-direction: column;
      gap: 15px;
    }
    .dot-nav a {
      width: 14px;
      height: 14px;
      background: #999;
      border-radius: 50%;
      transition: 0.3s;
    }
    .dot-nav a.active,
    .dot-nav a:hover {
      background: #00ffff;
      transform: scale(1.2);
    }
    section {
      width: 100vw;
      min-height: 100vh;
      display: flex;
      justify-content: center;
      align-items: center;
      background: rgba(0, 0, 0, 0.4);
      backdrop-filter: blur(6px);
      opacity: 0;
      transition: all 1s ease;
      padding: 80px 20px;
    }
    .section-content {
      width: 100%;
      max-width: 800px;
      padding: 40px;
      border-radius: 20px;
      background: rgba(0, 0, 0, 0.5);
      backdrop-filter: blur(12px);
      box-shadow: 0 0 30px rgba(0,255,255,0.1);
      text-align: center;
    }
    .section-content h1 {
      font-size: clamp(20px, 6vw, 36px);
      margin-bottom: 1rem;
      position: relative;
      padding-bottom: 0.5rem;
    }
    .section-content h1::after {
      content: "";
      position: absolute;
      bottom: 0;
      left: 50%;
      transform: translateX(-50%);
      width: 60px;
      height: 3px;
      background: #00ffff;
      border-radius: 2px;
    }
    .section-content p {
      font-size: 1.2rem;
      line-height: 1.6;
    }
    .avatar {
      width: 150px;
      height: 150px;
      border-radius: 50%;
      overflow: hidden;
      margin: 0 auto 20px;
      border: 4px solid #00ffff;
      box-shadow: 0 0 20px rgba(0,255,255,0.3);
    }
    .avatar img {
      width: 100%;
      height: 100%;
      object-fit: cover;
    }
    .about, .ky-nang, .du-an, .lien-he { transform: scale(0.9); }
    .show { opacity: 1 !important; transform: scale(1) !important; }

    #scrollTopBtn {
      position: fixed;
      bottom: 90px;
      right: 20px;
      background: #00ffff;
      color: #000;
      font-size: 20px;
      padding: 10px 15px;
      border: none;
      border-radius: 50%;
      box-shadow: 0 0 15px rgba(0,255,255,0.5);
      cursor: pointer;
      display: none;
      z-index: 9999;
    }
    #scrollTopBtn:hover { background: #00cccc; }

    #themeToggle {
      position: fixed;
      bottom: 20px;
      right: 20px;
      background: #444;
      border-radius: 50%;
      width: 45px;
      height: 45px;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      z-index: 1000;
    }
    #themeToggle i {
      font-size: 20px;
      color: #fff;
    }
    body.light {
      background: #f3f3f3;
      color: #222;
    }
    body.light .section-content {
      background: rgba(255,255,255,0.85);
      color: #111;
    }
    body.light .nav-text {
      background: rgba(255,255,255,0.6);
    }
    body.light .nav-text a {
      color: #333;
    }
    body.light .nav-text a.active,
    body.light .nav-text a:hover {
      color: #007bff;
    }
    body.light .dot-nav a {
      background: #999;
    }
    body.light .dot-nav a.active,
    body.light .dot-nav a:hover {
      background: #007bff;
    }
    body.light #scrollTopBtn {
      background: #007bff;
      color: white;
    }
    body.light #themeToggle {
      background: #ccc;
    }
    body.light #themeToggle i {
      color: #000;
    }
    @media (min-width: 769px) {
      .nav-text { display: none; }
      .dot-nav { display: flex; }
    }
    @media (max-width: 768px) {
      .dot-nav { display: none; }
    }

    .form-group {
      position: relative;
      margin-bottom: 20px;
    }
    .form-group i {
      position: absolute;
      top: 12px;
      left: 10px;
      color: #00ffff;
    }
    .form-group input,
    .form-group textarea {
      width: 100%;
      padding: 10px 10px 10px 36px;
      border-radius: 8px;
      border: none;
      background: rgba(255, 255, 255, 0.1);
      color: #fff;
    }
    .form-group textarea { resize: none; }
    .submit-btn {
      background: #00ffff;
      color: #000;
      padding: 10px 20px;
      border-radius: 8px;
      border: none;
      font-weight: bold;
      cursor: pointer;
      transition: 0.3s;
    }
    .submit-btn:hover { background: #00cccc; }
    .facebook-btn-wrapper {
      margin-top: 20px;
      text-align: center;
    }
    .facebook-btn {
      display: inline-flex;
      align-items: center;
      gap: 10px;
      background-color: #1877F2;
      color: #fff;
      padding: 10px 20px;
      border-radius: 30px;
      text-decoration: none;
      font-weight: bold;
      transition: 0.3s;
    }
    .facebook-btn:hover {
      background-color: #0e60d0;
    }
    body.light .form-group input,
    body.light .form-group textarea {
      background: rgba(0, 0, 0, 0.05);
      color: #000;
    }
    body.light .form-group i { color: #007bff; }
    body.light .submit-btn {
      background: #007bff;
      color: #fff;
    }
    body.light .submit-btn:hover {
      background: #0056b3;
    }
   
  #share-noi-btn {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background-color: #ff5e5e;
    color: white;
    border: none;
    border-radius: 30px;
    padding: 12px 24px;
    font-size: 16px;
    font-weight: bold;
    box-shadow: 0 4px 12px rgba(0,0,0,0.2);
    z-index: 999;
    cursor: pointer;
    transition: background-color 0.3s;
  }

  #share-noi-btn:hover {
    background-color: #e04e4e;
  }