/* main card container */
    .config-wrapper {
      max-width: 1100px;
      margin: 0 auto;
      background: rgba(255,255,255,0.7);
      border-radius: 3rem;
      backdrop-filter: blur(2px);
      padding: 1.5rem;
      box-shadow: 0 25px 45px -12px rgba(0,0,0,0.2);
    }

    #configurator {
      background: #ffffff;
      border-radius: 2rem;
      padding: 2rem 2rem 2.5rem;
      box-shadow: 0 8px 30px rgba(0, 0, 0, 0.05);
      transition: all 0.2s ease;
    }

    h1 {
      font-size: 1.9rem;
      font-weight: 700;
      background: linear-gradient(135deg, #1E3C5C, #2A5F8A);
      -webkit-background-clip: text;
      background-clip: text;
      color: transparent;
      margin-bottom: 1.8rem;
      letter-spacing: -0.3px;
      border-left: 5px solid #2A7FAA;
      padding-left: 1.2rem;
    }

    .section {
      margin-bottom: 2.5rem;
      border-bottom: 1px solid #e9edf2;
      padding-bottom: 1.5rem;
    }

    .section h3 {
      font-size: 1.3rem;
      font-weight: 600;
      color: #1e4663;
      margin-bottom: 1.2rem;
      display: flex;
      align-items: center;
      gap: 8px;
    }

    .section h3::before {
      content: "✦";
      font-size: 1.2rem;
      color: #2A7FAA;
      /*color:#7ac143;*/
    }

    /* options grid modern */
    .options {
      display: flex;
      flex-wrap: wrap;
      gap: 1rem;
      align-items: center;
    }

    .radio-card, .custom-card {
      background: #f8fafd;
      border: 1.5px solid #dfe5ef;
      border-radius: 2rem;
      padding: 0.6rem 1.4rem;
      font-weight: 500;
      cursor: pointer;
      transition: all 0.2s ease;
      box-shadow: 0 1px 2px rgba(0,0,0,0.02);
      font-size: 0.9rem;
      margin-right: 5px;
    }

    .radio-card.active, .custom-card.active {
      background: #1e4663;
      border-color: #1e4663;
      color: white;
      box-shadow: 0 6px 12px -8px rgba(30,70,99,0.4);
    }

    .radio-card input, .custom-card input {
      display: none;
    }

    .radio-content {
      display: inline-block;
    }

    /* credentials area: icon-style buttons */
    .credential-main-container {
      display: flex;
      flex-wrap: wrap;
      gap: 2rem;
      background: #fbfdff;
      padding: 1rem 0;
      border-radius: 1.5rem;
    }

    .credential-sub-container {
      flex: 1;
      min-width: 200px;
    }

    .options.credential-icons {
      display: flex;
      flex-wrap: wrap;
      gap: 1.2rem;
      margin-top: 0.8rem;
    }

    .credential-btn {
      background: #f1f5f9;
      border-radius: 1.5rem;
      padding: 0.7rem 1rem;
      cursor: pointer;
      transition: all 0.2s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 85px;
      border: 1.5px solid transparent;
    }

    .credential-btn img {
      width: 40px;
      height: 40px;
      object-fit: contain;
      filter: grayscale(0.2);
      transition: 0.2s;
    }

    .credential-btn img.active {
      filter: drop-shadow(0 4px 6px rgba(0,0,0,0.1)) brightness(1.05);
      transform: scale(1.02);
    }

    .credential-btn.active {
      background: #e9f0f9;
      border-color: #2A7FAA;
      box-shadow: 0 4px 12px rgba(42,127,170,0.2);
    }

    /* doors input */
    .door-container input {
      width: 220px;
      padding: 0.7rem 1rem;
      border-radius: 2rem;
      border: 1.5px solid #cfddee;
      font-size: 1rem;
      background: white;
      transition: 0.2s;
    }

    .door-container input:focus {
      border-color: #2A7FAA;
      outline: none;
      box-shadow: 0 0 0 3px rgba(42,127,170,0.2);
    }

    /* integration & management flex row */
    .integration-management-main-container {
      display: flex;
      flex-wrap: wrap;
      gap: 2rem;
      margin-top: 0.5rem;
    }

    .integration-management-container {
      /*background: #f9fbfe;*/
      /*border-radius: 1.5rem;*/
      padding: 1.2rem 1.5rem;
      flex: 1;
      /*box-shadow: 0 2px 6px rgba(0,0,0,0.02);*/
      /*border: 1px solid #eef2f8;*/
    }

    /* readers grid - premium cards */
    .options.readers-grid {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(190px, 1fr));
      gap: 1rem;
      margin-top: 1rem;
    }

    .option-btn.img-container {
      background: #ffffff;
      border-radius: 1.2rem;
      padding: 0.4rem 0.3rem;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 8px;
      font-weight: 500;
      font-size: 0.8rem;
      text-align: center;
      border: 1px solid #e2e9f2;
      transition: all 0.2s;
      cursor: default;
      box-shadow: 0 2px 6px rgba(0,0,0,0.02);
    }

    .option-btn.img-container img {
      width: 180px;
      height: 180px;
      object-fit: contain;
      background: #f8fafc;
      padding: 8px;
      border-radius: 1rem;
    }

    .option-btn.img-container span {
      color: #1e3a5f;
      font-size: 0.8rem;
      font-weight: 500;
    }

    .info-message {
      background: #eef2fa;
      padding: 1rem;
      border-radius: 1.2rem;
      color: #2c5a7a;
      text-align: center;
      font-weight: 500;
    }

    /* panel selection */
    .options.panel-flex {
      display: flex;
      gap: 1.8rem;
      flex-wrap: wrap;
    }

    .panel-container {
      background: #f9fcff;
      border-radius: 1.6rem;
      padding: 0.8rem;
      transition: all 0.2s;
      cursor: pointer;
      border: 2px solid transparent;
      box-shadow: 0 8px 14px rgba(0,0,0,0.05);
    }

    .panel-container.active {
      border-color: #2A7FAA;
      background: #eef6fd;
      transform: scale(1.02);
      box-shadow: 0 18px 28px -12px rgba(42,127,170,0.3);
    }

    .panel-container img {
      border-radius: 1rem;
      max-width: 220px;
      width: 100%;
      height: auto;
      display: block;
    }

    button.submit-btn {
      background: linear-gradient(95deg, #1e4663, #2c628b);
      border: none;
      color: white;
      font-weight: 600;
      padding: 0.9rem 2rem;
      font-size: 1rem;
      border-radius: 3rem;
      cursor: pointer;
      margin-top: 2rem;
      width: 100%;
      transition: all 0.2s ease;
      box-shadow: 0 5px 12px rgba(0,0,0,0.1);
      letter-spacing: 0.3px;
    }

    button.submit-btn:hover {
      background: linear-gradient(95deg, #123a56, #1f5579);
      transform: translateY(-2px);
      box-shadow: 0 12px 22px -10px rgba(0,0,0,0.2);
    }

    /* popup styling */
    .popup-overlay {
      display: none;
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: 100%;
      background: rgba(0,0,0,0.6);
      backdrop-filter: blur(6px);
      align-items: center;
      justify-content: center;
      z-index: 1000;
    }

    .popup-box {
      background: white;
      max-width: 520px;
      width: 90%;
      border-radius: 2rem;
      padding: 1.8rem 2rem;
      position: relative;
      box-shadow: 0 40px 50px rgba(0,0,0,0.3);
      animation: fadeUp 0.2s ease;
    }

    @keyframes fadeUp {
      from {
        opacity: 0;
        transform: translateY(20px);
      }
      to {
        opacity: 1;
        transform: translateY(0);
      }
    }

    .close-btn {
      position: absolute;
      right: 1.4rem;
      top: 1rem;
      font-size: 1.8rem;
      cursor: pointer;
      color: #8a9bb0;
    }

    .form-group {
      margin-bottom: 1rem;
    }

    .form-group label {
      font-weight: 600;
      font-size: 0.85rem;
      color: #1f3b4c;
    }

    .form-group input, .form-group textarea {
      width: 100%;
      padding: 0.7rem 0.9rem;
      border-radius: 1rem;
      border: 1px solid #cfdfed;
      font-family: inherit;
      margin-top: 4px;
    }

    .error {
      color: #c44536;
      font-size: 0.7rem;
      display: block;
      margin-top: 4px;
    }

    #response-msg {
      color: #2c7a4d;
      font-weight: 500;
    }

    .btn-primary {
      background: #1e4663;
      color: white;
      border: none;
      padding: 0.7rem 1rem;
      border-radius: 2rem;
      width: 100%;
      font-weight: bold;
      cursor: pointer;
    }

    hr {
      margin: 1rem 0;
    }

    @media (max-width: 760px) {
      body {
        padding: 1rem;
      }
      #configurator {
        padding: 1.2rem;
      }
      .credential-btn {
        width: 70px;
      }
    }