* {
      box-sizing: border-box;
    }
    main-content {
      display: block;
      font-family: 'Nunito', sans-serif, Arial, sans-serif;
      background: #bcc2c8;
      margin: 0;
      padding: 30px 20px;
      color: #00e1fa;
      min-height: 100vh;
    }

    /* .container {
      max-width: 1200px;
      margin: 0 auto;
    } */

    h1 {
      font-weight: 900;
      font-size: 2.8rem;
      margin-bottom: 25px;
      letter-spacing: -0.04em;
      line-height: 1.1;
    }

    .structure-grid {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
      gap: 30px;
    }

    .structure-card {
      background: #545454c1;
      border-radius: 15px;
      padding: 20px 20px 30px;
      box-shadow: 0 8px 20px rgb(51 53 90 / 0.1);
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      transition: transform 0.3s ease, box-shadow 0.3s ease;
    }
    .structure-card:hover {
      /* box-shadow: 0 12px 25px rgba(0, 247, 255, 0.45); */
      transform: translateY(-6px);
    }

    .structure-card h2 {
      font-weight: 600;
      font-size: 2rem;
      margin-bottom: 22px;
      color: #ffffff;
      text-align: center;
    }

    .image-wrapper {
      /* background: #4f5966; */
      padding: 20px;
      border-radius: 20px;
      max-width: 450px;
      width: 100%;
      display: flex;
      justify-content: center;
      align-items: center;
      box-shadow: inset 0 0 20px rgba(255 255 255 / 0.15);
      cursor: pointer;
      transition: filter 0.3s ease;
    }

    .image-wrapper img {
      max-width: 400px;
      height: auto;
      filter: grayscale(100%) contrast(1.2);
      border-radius: 8px;
      transition: filter 0.35s ease;
      pointer-events: none;
      user-select: none;
    }

    .image-wrapper:hover img {
      filter: grayscale(0%) contrast(1.1);
    }

    @media (max-width: 440px) {
      h1 {
        font-size: 2rem;
      }
      .structure-card h2 {
        font-size: 0.9rem;
      }
      .image-wrapper {
        max-width: 100%;
        padding: 20px;
      }
      .image-wrapper img {
        max-width: 100%;
      }
    }

    /* Modal Popup */
    .modal {
      position: fixed;
      display: none;
      top: 0; left: 0;
      width: 100vw;
      height: 100vh;
      background: rgba(0,0,0,0.75);
      justify-content: center;
      align-items: center;
      z-index: 1000;
      padding: 20px;
      overflow: auto;
    }
    .modal.active {
      display: flex;
    }
    .modal-content {
      position: relative;
      background: #ffffff64;
      padding: 15px;
      border-radius: 12px;
      max-width: 95vw;
      max-height: 90vh;
      box-shadow: 0 8px 30px rgba(0, 221, 255, 0.4);
      display: flex;
      justify-content: center;
      align-items: center;
    }
    .modal-content img {
      max-width: 100%;
      max-height: 85vh;
      border-radius: 10px;
      user-select: none;
      pointer-events: none;
    }
    .modal-close {
      position: absolute;
      top: 10px;
      right: 15px;
      background: #00ffea;
      color: #fff;
      border: none;
      border-radius: 50%;
      width: 32px;
      height: 32px;
      font-weight: 700;
      font-size: 20px;
      line-height: 32px;
      text-align: center;
      cursor: pointer;
      user-select: none;
      transition: background 0.3s ease;
    }
    .modal-close:hover {
      background: #052c65;
    }