/* TOÀN BỘ TRANG */
body {
    background-color: #0b0b0c;
    color: #f1f1f1;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    scroll-behavior: smooth;
    overflow-x: hidden;
  }
  
  a {
    text-decoration: none;
  }
  
  h2, h5 {
    font-weight: bold;
    text-transform: uppercase;
  }
  
  /* HEADER */
  .navbar {
    background-color: #121212 !important;
    box-shadow: 0 2px 10px rgba(255, 255, 255, 0.05);
  }
  
  .navbar-brand img {
    filter: drop-shadow(0 0 5px #fff);
  }
  
  .nav-link {
    color: #ccc !important;
    transition: 0.3s ease;
  }
  
  .nav-link:hover,
  .dropdown-item:hover {
    color: #fff !important;
    transform: scale(1.05);
  }
  
  /* DROPDOWN */
  .dropdown-menu {
    border: none;
    background-color: #1a1a1a;
  }
  
  /* CAROUSEL */
  .carousel img {
    height: 500px;
    object-fit: cover;
    filter: brightness(70%) contrast(110%);
    transition: transform 0.5s ease;
  }
  
  .carousel-item:hover img {
    transform: scale(1.02);
  }
  
  /* GIỚI THIỆU */
  .fade-in {
    animation: fadeInUp 1s ease-in-out both;
  }
  
  @keyframes fadeInUp {
    from {
      opacity: 0;
      transform: translateY(30px);
    }
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }
  
  #gioithieu h2 {
    font-family: 'Orbitron', sans-serif;
    font-size: 2rem;
    margin-bottom: 1rem;
  }
  
  #gioithieu p {
    font-family: 'Montserrat', sans-serif;
    font-size: 1.1rem;
    line-height: 1.7;
  }
  
  #gioithieu a.btn:hover {
    background-color: #ffc107;
    color: #212529;
    transition: 0.3s ease;
  }
  
  
  /* Developer Card */
  .dev-card {
    background-color: #1c1c1e;
    padding: 20px;
    border-radius: 15px;
    transition: 0.3s;
    box-shadow: 0 0 20px rgba(255, 255, 255, 0.02);
    border: 1px solid #2f2f2f;
    backdrop-filter: blur(3px);
  }
  
  .dev-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 30px rgba(255, 255, 255, 0.1);
  }
  
  .dev-img {
    width: 100%;
    height: 250px;
    object-fit: cover;
    border-radius: 10px;
    filter: brightness(90%);
  }
  
  .social-icons a {
    color: #f1f1f1;
    margin: 0 10px;
    font-size: 1.3rem;
    transition: 0.3s;
  }
  
  .social-icons a:hover {
    color: #00bfff;
    transform: scale(1.2);
  }
  
  /* Background kinh dị */
  .contact-section {
    background-image: url('https://i.imgur.com/Mz4rPGP.jpg');
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    position: relative;
  }
  
  .contact-section::before {
    content: "";
    position: absolute;
    top: 0; left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.75);
    backdrop-filter: blur(4px);
    z-index: 1;
  }
  
  .contact-section .container {
    position: relative;
    z-index: 2;
  }
  
  /* Tiêu đề rùng rợn */
  .spooky-title {
    font-family: 'Creepster', cursive;
    font-size: 36px;
    color: #ff4d4d;
    text-shadow: 0 0 10px red;
  }
  
  /* Input style */
  .contact-section input,
  .contact-section textarea {
    width: 100%;
    margin-bottom: 20px;
    background-color: rgba(20, 20, 20, 0.85);
    color: #fff;
    border: 1px solid #ff4d4d;
    border-radius: 8px;
    padding: 12px;
    transition: 0.3s ease;
  }
  
  .contact-section input:focus,
  .contact-section textarea:focus {
    box-shadow: 0 0 15px #ff4d4d;
    outline: none;
    background-color: #111;
  }
  
  /* Nút gửi style */
  .contact-section button {
    background-color: #ff4d4d;
    color: #fff;
    border: none;
    border-radius: 10px;
    padding: 12px 30px;
    font-weight: bold;
    text-transform: uppercase;
    transition: 0.3s ease;
  }
  
  .contact-section button:hover {
    background-color: #fff;
    color: #000;
    box-shadow: 0 0 15px red;
    transform: scale(1.05);
  }
  
  /* FOOTER */
  footer {
    border-top: 1px solid #333;
  }
  
  /* ANIMATION KEYFRAMES */
  @keyframes fadeInUp {
    from {
      opacity: 0;
      transform: translateY(20px);
    }
    to {
      opacity: 1;
      transform: translateY(0);
    }
  }
  
  /* RESPONSIVE */
  @media (max-width: 768px) {
    .dev-img {
      height: 200px;
    }
  
    .carousel img {
      height: 300px;
    }
  
    .navbar-nav {
      text-align: center;
    }
  
    .dropdown-menu {
      text-align: center;
    }
  }
  
  /* Nút ngôn ngữ */
.lang-btn {
    font-size: 0.85rem;
    padding: 6px 14px;
    border: 1px solid #ccc;
    border-radius: 50px;
    color: #fff;
    background-color: transparent;
    transition: all 0.3s ease;
    white-space: nowrap;
  }
  
  .lang-btn:hover {
    background-color: #ffc107;
    color: #000;
    border-color: #ffc107;
  }
  
  /* Responsive - hiển thị nút ngôn ngữ bên trong toggle menu khi mobile */
  @media (max-width: 991.98px) {
    .lang-btn {
      display: inline-block;
      margin-top: 10px;
    }
  }
  
  /* Fade in hiệu ứng vào */
.fade-in {
    animation: fadeIn 1s ease-in;
  }
  
  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }
  
  /* Hiệu ứng hover nút đẹp */
  .transition-hover {
    transition: all 0.3s ease;
  }
  
  .transition-hover:hover {
    background-color: #ffc107;
    color: #000;
    border-color: #ffc107;
    transform: scale(1.05);
  }