:root {
      --brand-green: #16a34a;
      --brand-white: #ffffff;
      --muted: #6b7280;
    }
    body {
      font-family: Arial, sans-serif;
      margin: 0;
      background: #f9fafb;
      color: #111827;
    }

    /* Header */
    .header {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 12px 20px;
      background: var(--brand-green);
      color: var(--brand-white);
    }
    .username {
      font-weight: bold;
      font-size: 16px;
    }
    .social-icons a {
      margin-left: 12px;
      color: var(--brand-white);
      font-size: 18px;
      text-decoration: none;
    }

    /* Containers */
    .quiz-container {
      max-width: 700px;
      margin: 20px auto;
      background: #fff;
      padding: 20px;
      border-radius: 12px;
      box-shadow: 0 4px 10px rgba(0,0,0,0.08);
    }

    /* Email Step */
    #email-step, #instructions-step {
      text-align: center;
    }
    #email-step input {
      width: 80%;
      padding: 12px;
      margin: 10px 0;
      border: 1px solid #ddd;
      border-radius: 8px;
      font-size: 16px;
    }
    #email-step button {
      padding: 10px 16px;
      border: none;
      border-radius: 8px;
      cursor: pointer;
      background: var(--brand-green);
      color: #fff;
      font-weight: bold;
    }
    #instructions-step {
      display: none;
    }
    #instructions-step h2 {
      color: var(--brand-green);
    }
    #instructions-step ul {
      text-align: left;
      margin: 10px auto;
      max-width: 500px;
    }
    #instructions-step button {
      margin-top: 15px;
      padding: 10px 16px;
      border: none;
      border-radius: 8px;
      cursor: pointer;
      background: var(--brand-green);
      color: #fff;
      font-weight: bold;
    }

    /* Quiz */
    .timer {
      text-align: right;
      font-weight: bold;
      color: var(--brand-green);
    }
    .question {
      font-size: 18px;
      margin-bottom: 15px;
    }
    .options label {
      display: block;
      margin-bottom: 10px;
      padding: 10px;
      border: 1px solid #ddd;
      border-radius: 8px;
      cursor: pointer;
      transition: background 0.2s, border 0.2s;
    }
    .options input {
      margin-right: 10px;
    }
    .options label:hover {
      background: #f0fdf4;
      border-color: var(--brand-green);
    }

    /* Buttons */
    .nav-buttons {
      margin-top: 20px;
      display: flex;
      justify-content: space-between;
    }
    button {
      padding: 10px 16px;
      border: none;
      border-radius: 8px;
      cursor: pointer;
      background: var(--brand-green);
      color: #fff;
      font-weight: bold;
    }
    button:disabled {
      opacity: 0.6;
      cursor: not-allowed;
    }

    /* Progress */
    .progress {
      margin-top: 20px;
      text-align: center;
    }
    .progress span {
      display: inline-block;
      width: 32px;
      height: 32px;
      line-height: 32px;
      border-radius: 50%;
      margin: 4px;
      background: #e5e7eb;
      color: #111;
      cursor: pointer;
      font-weight: bold;
    }
    .progress span.answered {
      background: var(--brand-green);
      color: #fff;
    }

    /* Results */
    #results {
      display: none;
      margin-top: 20px;
    }
    .question-block {
      background: #f9fafb;
      padding: 14px;
      margin-bottom: 12px;
      border-radius: 8px;
      border: 1px solid #e5e7eb;
    }
    .correct { color: green; font-weight: bold; }
    .wrong { color: red; font-weight: bold; }