/* 手机端适配 (小于 768px) */
@media (max-width: 767px) {
  :root {
    font-size: 14px;
  }

  .screen {
    padding: 12px;
  }

  .header h1 {
    font-size: 1.3em;
  }

  .feature-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }

  .feature-card {
    padding: 16px 12px;
  }

  .feature-card .icon {
    font-size: 2em;
  }

  .feature-card .title {
    font-size: 0.9em;
  }

  .char-display {
    font-size: 3em;
    padding: 30px 16px;
  }

  .options-grid {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .option-btn {
    padding: 14px;
    font-size: 1.1em;
  }

  .btn {
    padding: 14px 24px;
    font-size: 1em;
  }

  .card {
    padding: 16px;
  }

  .feedback {
    padding: 24px 32px;
    min-width: 160px;
  }

  .feedback .feedback-icon {
    font-size: 2.5em;
  }
}

/* 小屏幕手机 (小于 375px) */
@media (max-width: 374px) {
  .feature-grid {
    gap: 8px;
  }

  .feature-card {
    padding: 12px 8px;
  }

  .feature-card .icon {
    font-size: 1.8em;
  }

  .feature-card .title {
    font-size: 0.85em;
  }

  .char-display {
    font-size: 2.5em;
    padding: 24px 12px;
  }
}