:root {
    --primary: linear-gradient(135deg, #0d47a1, #6a1b9a);
    --secondary: rgba(255, 255, 255, 0.1);
    --accent: linear-gradient(45deg, #ffeb3b, #ff9800);
    --text: #ffffff;
    --card-bg: rgba(255, 255, 255, 0.05);
    --transition: all 0.3s ease;
  }

  @font-face {
    font-family: 'Montserrat';
    src: url('https://fonts.googleapis.com/css2?family=Montserrat:wght@400;600&display=swap');
  }

  @font-face {
    font-family: 'Roboto';
    src: url('https://fonts.googleapis.com/css2?family=Roboto:wght@700&display=swap');
  }

  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }

  body {
    background: var(--primary);
    color: var(--text);
    font-family: 'Montserrat', sans-serif;
    line-height: 1.6;
    overflow-x: hidden;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
  }

  header {
    padding: 2rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
  }

  header::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.gptkong.com/demo/sample1.png') center/cover no-repeat;
    opacity: 0.2;
    z-index: -1;
  }

  h1, h2, h3 {
    font-family: 'Roboto', sans-serif;
    background: linear-gradient(90deg, #00c6ff, #0072ff);
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    margin-bottom: 1.5rem;
  }

  h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
  }

  h2 {
    font-size: 2rem;
    margin-top: 3rem;
    position: relative;
    padding-bottom: 0.5rem;
  }

  h2::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100px;
    height: 3px;
    background: var(--accent);
  }

  h3 {
    font-size: 1.5rem;
    margin-top: 2rem;
  }

  p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
  }

  .notice {
    background: rgba(0, 0, 0, 0.3);
    padding: 1rem;
    border-left: 4px solid #ff9800;
    margin: 2rem 0;
    font-size: 0.9rem;
  }

  .grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
  }

  .card {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 2rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    backdrop-filter: blur(10px);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
  }

  .card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3);
  }

  .card::after {
    content: "";
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: linear-gradient(
      to bottom right,
      rgba(255, 255, 255, 0) 0%,
      rgba(255, 255, 255, 0.1) 50%,
      rgba(255, 255, 255, 0) 100%
    );
    transform: rotate(30deg);
    transition: var(--transition);
    opacity: 0;
  }

  .card:hover::after {
    animation: shine 1.5s;
  }

  @keyframes shine {
    0% {
      transform: rotate(30deg) translate(-30%, -30%);
      opacity: 0;
    }
    20% {
      opacity: 1;
    }
    100% {
      transform: rotate(30deg) translate(30%, 30%);
      opacity: 0;
    }
  }

  .card-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: 10px;
    margin-bottom: 1.5rem;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
    transition: var(--transition);
  }

  .card:hover .card-img {
    transform: scale(1.05);
  }

  pre {
    background: rgba(0, 0, 0, 0.3);
    border-radius: 10px;
    padding: 1.5rem;
    margin: 2rem 0;
    overflow: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    position: relative;
  }

  pre::before {
    content: "CSS";
    position: absolute;
    top: 0;
    right: 0;
    background: var(--accent);
    color: #000;
    padding: 0.2rem 0.5rem;
    border-radius: 0 0 0 10px;
    font-size: 0.8rem;
    font-weight: bold;
  }

  code {
    font-family: 'Courier New', monospace;
    background: rgba(0, 0, 0, 0.2);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    font-size: 0.9rem;
  }

  .nav {
    position: sticky;
    top: 0;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(10px);
    padding: 1rem 0;
    z-index: 100;
  }

  .nav-list {
    display: flex;
    justify-content: center;
    list-style: none;
    gap: 2rem;
  }

  .nav-link {
    color: var(--text);
    text-decoration: none;
    font-weight: 600;
    padding: 0.5rem 1rem;
    border-radius: 20px;
    transition: var(--transition);
  }

  .nav-link:hover {
    background: rgba(255, 255, 255, 0.1);
  }

  .footer {
    text-align: center;
    padding: 3rem 0;
    margin-top: 3rem;
    background: rgba(0, 0, 0, 0.3);
  }

  .img-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 1rem;
    margin: 2rem 0;
  }

  .img-grid img {
    width: 100%;
    height: 150px;
    object-fit: cover;
    border-radius: 10px;
    transition: var(--transition);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
  }

  .img-grid img:hover {
    transform: scale(1.05);
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.3);
  }

  @media (max-width: 768px) {
    .grid {
      grid-template-columns: 1fr;
    }

    .nav-list {
      flex-direction: column;
      align-items: center;
      gap: 1rem;
    }

    h1 {
      font-size: 2rem;
    }

    h2 {
      font-size: 1.5rem;
    }

    h3 {
      font-size: 1.2rem;
    }
  }

  @keyframes float {
    0%, 100% {
      transform: translateY(0);
    }
    50% {
      transform: translateY(-20px);
    }
  }

  .floating {
    animation: float 6s ease-in-out infinite;
  }

  .highlight-box {
    background: rgba(255, 255, 255, 0.1);
    border-left: 4px solid #ff9800;
    padding: 1.5rem;
    margin: 2rem 0;
    border-radius: 0 10px 10px 0;
  }

  .btn {
    display: inline-block;
    background: var(--accent);
    color: #000;
    padding: 0.8rem 1.5rem;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    margin: 1rem 0;
  }

  .btn:hover {
    transform: translateY(-3px);
    box-shadow: 0 10px 20px rgba(255, 152, 0, 0.3);
  }