:root {
      --osh-navy: #17365d;
      --osh-blue: #1f5f99;
      --osh-light-blue: #e8f2fb;
      --osh-gold: #f2b705;
      --osh-green: #2f855a;
      --osh-red: #c53030;
      --osh-gray: #f4f6f8;
      --text: #1f2933;
      --white: #ffffff;
      --shadow: 0 8px 24px rgba(23, 54, 93, 0.16);
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: Arial, Helvetica, sans-serif;
      background: linear-gradient(180deg, var(--osh-light-blue), var(--white));
      color: var(--text);
      line-height: 1.5;
    }

    .app {
      width: min(100%, 760px);
      margin: 0 auto;
      padding: 16px;
    }

    .header {
      background: var(--osh-navy);
      color: var(--white);
      padding: 22px 18px;
      border-radius: 18px;
      box-shadow: var(--shadow);
      border-top: 6px solid var(--osh-gold);
    }

    .eyebrow {
      margin: 0 0 6px;
      font-size: 0.78em;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: var(--osh-gold);
      font-weight: 700;
    }

    h1 {
      margin: 0;
      font-size: clamp(1.35em, 5vw, 2em);
      line-height: 1.15;
    }

    .subtitle {
      margin: 10px 0 0;
      color: #dbeafe;
      font-size: 0.98em;
    }

    .card {
      background: var(--white);
      border-radius: 18px;
      box-shadow: var(--shadow);
      padding: 18px;
      margin-top: 16px;
      border: 1px solid #d8e2ee;
    }

    h2 {
      color: var(--osh-navy);
      font-size: 1.2em;
      margin: 0 0 8px;
    }

    ul {
      padding-left: 1.2em;
      margin: 8px 0;
    }

    .decision {
      background: var(--osh-gray);
      border-left: 6px solid var(--osh-gold);
    }

    .choices {
      display: grid;
      gap: 10px;
      margin-top: 12px;
    }

    button.choice {
      width: 100%;
      border: 2px solid #c9d7e6;
      background: var(--white);
      color: var(--text);
      text-align: left;
      padding: 14px;
      border-radius: 14px;
      font-size: 1em;
      cursor: pointer;
      transition: transform 0.12s ease, border-color 0.12s ease, background 0.12s ease;
      min-height: 54px;
    }

    button.choice:hover {
      transform: translateY(-1px);
      border-color: var(--osh-blue);
      background: #f8fbff;
    }

    button.choice:focus-visible {
      outline: 3px solid rgba(242, 183, 5, 0.45);
      outline-offset: 2px;
      transform: translateY(-1px);
      border-color: var(--osh-blue);
      background: #f8fbff;
    }

    button.choice.correct {
      border-color: var(--osh-green);
      background: #ecfdf3;
    }

    button.choice.incorrect {
      border-color: var(--osh-red);
      background: #fff5f5;
    }

    .letter {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      width: 28px;
      height: 28px;
      margin-right: 8px;
      border-radius: 999px;
      background: var(--osh-navy);
      color: var(--white);
      font-weight: 700;
      font-size: 0.9em;
      vertical-align: middle;
    }

    .feedback {
      display: none;
      margin-top: 14px;
      padding: 16px;
      border-radius: 14px;
      border: 2px solid transparent;
    }

    .feedback.show {
      display: block;
    }

    .feedback.correct {
      border-color: var(--osh-green);
      background: #ecfdf3;
    }

    .feedback.incorrect {
      border-color: var(--osh-red);
      background: #fff5f5;
    }

    .feedback-title {
      margin: 0 0 8px;
      font-weight: 800;
      font-size: 1.05em;
    }

    .feedback.correct .feedback-title {
      color: var(--osh-green);
    }

    .feedback.incorrect .feedback-title {
      color: var(--osh-red);
    }

    .actions {
      display: flex;
      gap: 10px;
      flex-wrap: wrap;
      margin-top: 14px;
    }

    .reset-btn {
      border: 0;
      background: var(--osh-blue);
      color: var(--white);
      padding: 12px 16px;
      border-radius: 12px;
      font-weight: 700;
      cursor: pointer;
      min-height: 48px;
    }

    .reset-btn:hover,
    .reset-btn:focus {
      background: var(--osh-navy);
      outline: 3px solid rgba(242, 183, 5, 0.45);
    }

    @media (max-width: 480px) {
      .app {
        padding: 10px;
      }

      .header,
      .card {
        border-radius: 14px;
      }

      button.choice {
        font-size: 0.96em;
        padding: 13px 12px;
      }
    }