:root {
      --panel-opacity: 0.85; /* default opacity for the white panel */
    }

    /* Page resets */
    * { box-sizing: border-box; }
    html, body {
      height: 100%;
      margin: 0;
      font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, sans-serif;
    }

    /* Full-bleed background */
    .bg {
      position: fixed;
      inset: 0;
      background: url("https://wwww.kin2000.com/d/dhca/images/booking.jpg") center / cover no-repeat;
      z-index: -1;
    }

    /* Centering container */
    .center-wrap {
      min-height: 100%;
      display: grid;
      place-items: center;
      padding: 2rem;
    }

    /* Overlay panel */
    .panel {
      width: min(800px, 100%);
      background: rgba(255, 255, 255, var(--panel-opacity));
      backdrop-filter: saturate(120%) blur(0.5px); /* subtle polish */
      border-radius: 16px;
      box-shadow:
        0 10px 25px rgba(0, 0, 0, 0.25),
        0 2px 8px rgba(0, 0, 0, 0.1);
      overflow: hidden;
    }

    /* Panel header with slider */
    .panel-header {
      display: flex;
      align-items: center;
      gap: 1rem;
      padding: 1rem 1.25rem;
      border-bottom: 1px solid rgba(0,0,0,0.08);
    }

    .panel-header label {
      font-weight: 600;
      white-space: nowrap;
    }

    .panel-header input[type="range"] {
      flex: 1 1 auto;
    }

    .opacity-value {
      font-variant-numeric: tabular-nums;
      min-width: 3ch;
      text-align: right;
    }

    /* Panel content */
    .panel-content {
      padding: 1.5rem 1.25rem 1.75rem;
      color: #111;
    }

    .panel-content p {
      line-height: 1.6;
      margin: 0 0 1rem;
    }

    /* Responsive tweaks */
    @media (max-width: 480px) {
      .panel {
        border-radius: 12px;
      }
      .panel-content {
        padding: 1rem 1rem 1.25rem;
      }
    }