:root {
    --primary-dark: #000428;
    --primary-darker: #000000;
    --accent-blue: #1E90FF;
    --accent-light: #63B3ED;
    --highlight-purple: #9D50BB;
    --text-light: rgba(255,255,255,0.9);
    --text-lighter: #FFFFFF;
    --transition-base: all 0.4s cubic-bezier(0.65, 0, 0.35, 1);
  }

  @font-face {
    font-family: 'Roboto';
    src: url('https://fonts.gstatic.com/s/roboto/v30/KFOmCnqEu92Fr1Mu4mxK.woff2') format('woff2');
    font-display: swap;
  }

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

  body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.8;
    color: var(--text-light);
    background: linear-gradient(135deg, var(--primary-darker), var(--primary-dark));
    background-attachment: fixed;
    overflow-x: hidden;
    position: relative;
    min-height: 100%;
    padding-bottom: 100px;
  }

  body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(circle at 70% 30%, rgba(157, 80, 187, 0.15) 0%, transparent 40%),
                radial-gradient(circle at 30% 70%, rgba(30, 144, 255, 0.15) 0%, transparent 40%);
    pointer-events: none;
    z-index: -1;
  }

  .design-notice {
    position: fixed;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    background: rgba(0,0,0,0.7);
    color: var(--accent-light);
    padding: 8px 20px;
    border-radius: 30px;
    font-size: 14px;
    backdrop-filter: blur(5px);
    z-index: 1000;
    box-shadow: 0 5px 15px rgba(0,0,0,0.3);
  }

  .particle {
    position: absolute;
    width: 2px;
    height: 2px;
    background: rgba(255, 255, 255, 0.6);
    border-radius: 50%;
    animation: drift 15s linear infinite;
    z-index: -1;
  }

  @keyframes drift {
    0% {
      transform: translate(0, 0);
      opacity: 0;
    }
    10% {
      opacity: 1;
    }
    90% {
      opacity: 1;
    }
    100% {
      transform: translate(100vw, -100vh);
      opacity: 0;
    }
  }

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

  header {
    padding: 30px 0;
    position: relative;
  }

  .header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .logo {
    font-size: 28px;
    font-weight: 700;
    color: var(--text-lighter);
    text-decoration: none;
    display: flex;
    align-items: center;
  }

  .logo::before {
    content: '';
    display: inline-block;
    width: 40px;
    height: 40px;
    background: url('https://images.gptkong.com/demo/sample1.png') no-repeat center;
    background-size: contain;
    margin-right: 15px;
    border-radius: 50%;
    box-shadow: 0 0 20px var(--accent-blue);
  }

  nav ul {
    display: flex;
    list-style: none;
  }

  nav li {
    margin-left: 30px;
    position: relative;
  }

  nav a {
    color: var(--text-light);
    text-decoration: none;
    font-weight: 500;
    font-size: 16px;
    position: relative;
    transition: var(--transition-base);
    padding: 5px 0;
  }

  nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-blue);
    transition: var(--transition-base);
  }

  nav a:hover {
    color: var(--text-lighter);
  }

  nav a:hover::after {
    width: 100%;
  }

  main {
    margin-top: 50px;
  }

  article {
    background: rgba(0, 4, 40, 0.6);
    border-radius: 20px;
    padding: 40px;
    backdrop-filter: blur(10px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.3);
    position: relative;
    overflow: hidden;
  }

  article::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(30,144,255,0.1) 0%, transparent 70%);
    animation: rotate 60s linear infinite;
    z-index: -1;
  }

  @keyframes rotate {
    from {
      transform: rotate(0deg);
    }
    to {
      transform: rotate(360deg);
    }
  }

  h2 {
    font-size: 32px;
    margin-bottom: 30px;
    color: var(--text-lighter);
    position: relative;
    padding-bottom: 15px;
  }

  h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 80px;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-blue), var(--highlight-purple));
    border-radius: 3px;
  }

  h3 {
    font-size: 24px;
    margin: 40px 0 20px;
    color: var(--text-lighter);
  }

  p {
    margin-bottom: 20px;
    font-size: 17px;
    line-height: 1.8;
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
    margin: 40px 0;
  }

  .image-card {
    background: rgba(255,255,255,0.05);
    border-radius: 15px;
    overflow: hidden;
    transition: var(--transition-base);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    position: relative;
  }

  .image-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(30,144,255,0.3);
  }

  .image-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    display: block;
  }

  .image-card::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, transparent 60%, rgba(0,0,0,0.7));
  }

  pre {
    background: rgba(0, 0, 20, 0.8);
    border-radius: 10px;
    padding: 20px;
    margin: 30px 0;
    overflow-x: auto;
    box-shadow: inset 0 0 10px rgba(0,0,0,0.5);
    border-left: 3px solid var(--accent-blue);
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background: var(--accent-blue);
    color: white;
    padding: 3px 10px;
    font-size: 12px;
    border-bottom-left-radius: 5px;
  }

  code {
    font-family: 'Roboto Mono', monospace;
    font-size: 15px;
    color: #e1e1e1;
  }

  .code-highlight {
    color: var(--accent-light);
  }

  footer {
    text-align: center;
    margin-top: 80px;
    padding: 30px 0;
    font-size: 14px;
    color: rgba(255,255,255,0.6);
  }

  .scroll-top {
    position: fixed;
    bottom: 80px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--accent-blue);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    opacity: 0;
    transition: var(--transition-base);
    box-shadow: 0 5px 15px rgba(30,144,255,0.4);
    z-index: 999;
  }

  .scroll-top.visible {
    opacity: 1;
  }

  .scroll-top:hover {
    transform: translateY(-5px);
    background: var(--accent-light);
  }

  @media (max-width: 768px) {
    .header-content {
      flex-direction: column;
      text-align: center;
    }

    nav ul {
      margin-top: 20px;
      justify-content: center;
    }

    nav li {
      margin: 0 10px;
    }

    article {
      padding: 30px 20px;
    }

    h2 {
      font-size: 28px;
    }

    h3 {
      font-size: 22px;
    }
  }

  @media (max-width: 480px) {
    .image-grid {
      grid-template-columns: 1fr;
    }
  }