* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: sans-serif;
  }
  
  /* HEADER */
  .header {
    position: sticky;
    top: 0;
    background: #111;
    color: #fff;
    padding: 15px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 10;
  }
  
  .nav a {
    color: #fff;
    margin-left: 20px;
    text-decoration: none;
  }
  
  .nav a.active {
    color: orange;
  }
  
  .menu-btn {
    display: none;
    cursor: pointer;
  }
  
  /* HERO */
  .hero {
    height: 80vh;
    background: linear-gradient(120deg,#4facfe,#00f2fe);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    color: white;
  }
  
  .btn {
    margin-top: 20px;
    padding: 10px 25px;
    border: none;
    background: black;
    color: white;
    cursor: pointer;
    transition: 0.3s;
  }
  
  .btn:hover {
    transform: scale(1.1);
  }
  
  /* GRID */
  .grid {
    padding: 50px;
    display: grid;
    grid-template-columns: repeat(auto-fit,minmax(200px,1fr));
    gap: 20px;
  }
  
  .card {
    background: #eee;
    padding: 50px;
    text-align: center;
    transition: 0.5s;
  }
  
  .card:hover {
    transform: rotateY(15deg) scale(1.05);
  }
  
  /* SLIDER */
  .slider {
    padding: 50px;
  }
  
  .swiper-slide {
    background: #333;
    color: white;
    height: 150px;
    display:flex;
    align-items:center;
    justify-content:center;
  }
  
  /* MOBILE */
  @media (max-width:768px) {
    .nav {
      position: absolute;
      top: 60px;
      right: 0;
      background: #111;
      flex-direction: column;
      display: none;
    }
  
    .nav.show {
      display: flex;
      animation: slideDown .3s ease;
    }
  
    .menu-btn {
      display: block;
    }
  }
  
  @keyframes slideDown {
    from {transform: translateY(-20px); opacity:0;}
    to {transform: translateY(0); opacity:1;}
  }
/* CONTACT FORM */
.contact {
    padding: 80px 20px;
    max-width: 500px;
    margin: auto;
  }
  
  .field {
    position: relative;
    margin-bottom: 30px;
  }
  
  .field input,
  .field textarea {
    width: 100%;
    padding: 12px;
    border: 1px solid #aaa;
    outline: none;
    font-size: 16px;
  }
  
  .field label {
    position: absolute;
    top: 12px;
    left: 12px;
    color: #666;
    pointer-events: none;
    transition: 0.3s;
  }
  
  .field input:focus + label,
  .field input:valid + label,
  .field textarea:focus + label,
  .field textarea:valid + label {
    top: -10px;
    font-size: 12px;
    background: white;
    padding: 0 5px;
    color: #000;
  }
  
  .field small {
    color: red;
  }
  
  .loader {
    width: 18px;
    height: 18px;
    border: 3px solid white;
    border-top-color: transparent;
    border-radius: 50%;
    display: none;
    animation: spin 1s linear infinite;
  }
  
  button.loading .btn-text {
    display: none;
  }
  
  button.loading .loader {
    display: inline-block;
  }
  
  @keyframes spin {
    to { transform: rotate(360deg); }
  }
  
  /* TOAST */
  .toast {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: black;
    color: white;
    padding: 15px 25px;
    opacity: 0;
    transform: translateY(20px);
    transition: 0.4s;
  }
  
  .toast.show {
    opacity: 1;
    transform: translateY(0);
  }
/* PARALLAX */
.parallax {
    background-attachment: fixed;
  }
  
  .parallax-box {
    height: 300px;
    background-image: url("https://picsum.photos/1200/600");
    background-size: cover;
    background-position: center;
    background-attachment: fixed;
    display: flex;
    justify-content: center;
    align-items: center;
    color: white;
    font-size: 40px;
  }  
  /* TABS */
.tabs {
    padding: 50px;
    text-align: center;
  }
  
  .tab-buttons {
    margin-bottom: 20px;
  }
  
  .tab {
    padding: 10px 20px;
    border: none;
    margin: 5px;
    cursor: pointer;
  }
  
  .tab.active {
    background: black;
    color: white;
  }
  
  .tab-content {
    display: none;
  }
  
  .tab-content.active {
    display: block;
  }
/* ACCORDION */
.faq {
    padding: 50px;
    max-width: 600px;
    margin: auto;
  }
  
  .faq-item {
    border-bottom: 1px solid #ccc;
    padding: 15px 0;
    cursor: pointer;
  }
  
  .faq-title {
    font-weight: bold;
  }
  
  .faq-content {
    max-height: 0;
    overflow: hidden;
    transition: 0.4s;
  }
  
  .faq-item.active .faq-content {
    max-height: 100px;
    margin-top: 10px;
  }
  /* ===== FAQ ACCORDION ===== */
.faq {
    width: 80%;
    margin: 50px auto;
  }
  
  .faq-item {
    border-bottom: 1px solid #ddd;
    padding: 15px 0;
    cursor: pointer;
  }
  
  .faq-title {
    font-weight: bold;
    font-size: 18px;
  }
  
  .faq-content {
    display: none;
    padding-top: 10px;
    color: #555;
  }
  
  /* Khi click -> hiện nội dung */
  .faq-item.active .faq-content {
    display: block;
  }
  .faq-item {
    cursor: pointer;
    border-bottom: 1px solid #ddd;
    padding: 15px 0;
  }
  
  .faq-content {
    display: none;
  }
  
  .faq-item.active .faq-content {
    display: block;
  }