<style>
      :root {
        --grad-from: #6a11cb;
        --grad-via: #8a3ffc;
        --grad-to: #ff4b2b;
        --bg: #ffffff;
        --text: #000;
        --muted: #fff;
        --card: #ffffff;
        --ok: #065f46;
        --ok-bg: #ecfdf5;
        --err: #991b1b;
        --err-bg: #fef2f2;
        --border: #e5e7eb;
        --shadow: 0 6px 24px rgba(0, 0, 0, 0.08), 0 2px 6px rgba(0, 0, 0, 0.06);
        --radius: 18px;
        font-family: Poppins, system-ui, -apple-system, Segoe UI, Roboto,
          Helvetica, Arial, 'Apple Color Emoji', 'Segoe UI Emoji';
      }
      body {
        margin: 0;
        background: var(--bg);
        color: #000;
      }
      .container {
        max-width: 720px;
        margin: 48px auto;
        padding: 0 16px;
      }
      .card {
        background: var(--card);
        border: 1px solid var(--border);
        border-radius: var(--radius);
        box-shadow: var(--shadow);
        padding: 24px;
      }
      p.lead {
        margin: 0;
        color: var(--muted);
      }
      .field {
        margin-top: 40px;
      }
      .label {
        display: block;
        font-size: 20px;
        font-weight: 600;
      }
      input[type='range'] {
        width: 100%;
      }
      .scale {
        display: grid;
        gap: 8px;
      }
      .scale.cols-6 {
        grid-template-columns: repeat(6, 1fr);
            flex-direction: row;
            justify-content: space-between;
      }
      .scale.cols-6 span {
        font-size: 12px;
      }
      .scale.cols-12 {
        grid-template-columns: repeat(12, 1fr);
            flex-direction: row;
            justify-content: space-between;
      }
      .scale.cols-12 span {
        font-size: 12px;
      }
      .tick {
        font-size: 12px;
        color: var(--muted);
        text-align: center;
      }
      .tick.active {
        color: #fff;
        font-weight: bold;
      }
      .row {
        display: flex;
        gap: 12px;
        flex-wrap: wrap;
        align-items: center;
        margin-top: 16px;
      }
      .btn {
        appearance: none;
        border: 0;
        border-radius: 16px;
        padding: 12px 18px;
        font-weight: 700;
        cursor: pointer;
        color: #fff;
        background-image: linear-gradient(
          90deg,
          var(--grad-from),
          var(--grad-via),
          var(--grad-to)
        );
        box-shadow: var(--shadow);
      }
      .btn[disabled] {
        opacity: 0.6;
        cursor: not-allowed;
      }
      .alert {
        margin-top: 16px;
        border-radius: 14px;
        padding: 12px 14px;
        font-size: 14px;
        border: 1px solid;
      }
      .alert.ok {
        color: var(--ok);
        background: var(--ok-bg);
        border-color: #bbf7d0;
      }
      .alert.err {
        color: var(--err);
        background: var(--err-bg);
        border-color: #fecaca;
      }