/* 第三课局部样式：纯色背景、表格示范、正常文档流导航。 */
.height-chart-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px; margin: 20px 0; }
.height-chart-grid figure { min-width: 0; margin: 0; padding: 14px; background: #fff; border: 1px solid #d6e1ec; border-radius: 10px; }
.height-chart-grid figcaption { font-size: 21px; font-weight: 700; margin-bottom: 12px; }
.height-chart-grid p { font-size: 19px; }
@media (max-width: 820px) { .height-chart-grid { grid-template-columns: 1fr; } }
.prepared-lesson .lesson-content { flex: 1; min-width: 0; }
.prepared-lesson .page-nav { position: static; display: flex; flex-wrap: wrap; gap: 12px; align-items: center; justify-content: space-between; margin-top: 26px; padding-top: 16px; border-top: 1px solid #dce3ed; }
.prepared-lesson .lesson-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); gap: 18px; margin: 22px 0; }
.prepared-lesson .lesson-cards article { padding: 22px; border: 1px solid #dbe5f2; border-top: 4px solid #2463a9; border-radius: 10px; background: #f2f7ff; }
.prepared-lesson .lesson-cards article:nth-child(2) { border-top-color: #238474; background: #f0f8f5; }
.prepared-lesson .lesson-cards article:nth-child(3) { border-top-color: #8c62a6; background: #f7f3fa; }
.prepared-lesson .lesson-cards article:nth-child(4) { border-top-color: #b66a23; background: #fff7ed; }
.prepared-lesson .lesson-cards p, .prepared-lesson .assignment li { font-size: 23px; margin: 8px 0; }
.prepared-lesson .lesson-content > table, .prepared-lesson .cover-example table { border-collapse: collapse; width: 100%; font-size: 23px; margin: 20px 0; }
.prepared-lesson .lesson-content th, .prepared-lesson .lesson-content td { border: 1px solid #bbcce0; padding: 14px 18px; text-align: left; }
.prepared-lesson .lesson-content th { background: #eaf2fc; color: #183b64; }
.prepared-lesson caption { text-align: left; font-weight: 700; padding: 0 0 12px; color: #23476c; }
.prepared-lesson .occupied { background: #e9f6f0; }
.prepared-lesson .answer { border: 1px solid #c6d9e9; border-radius: 9px; padding: 14px 20px; margin-top: 18px; background: #f4f8fc; font-size: 22px; }
.prepared-lesson .answer summary { cursor: pointer; font-weight: 700; color: #205b90; }
.prepared-lesson .answer p { margin-bottom: 4px; }
.prepared-lesson .assignment { padding: 24px; background: #f3f7fc; border-left: 5px solid #2463a9; border-radius: 10px; }
.prepared-lesson .url, .prepared-lesson .resource { overflow-wrap: anywhere; font-size: 18px; }
.prepared-lesson .code-playground .play-editor textarea, .prepared-lesson .code-playground .play-colors { font-size: 22px; line-height: 1.5; }
.prepared-lesson .lesson-toc { display: grid; grid-template-columns: repeat(3, minmax(0,1fr)); gap: 8px 22px; margin: 24px 0; }
.prepared-lesson .lesson-toc a { padding: 10px 0; border-bottom: 1px solid #dce4ef; font-size: 19px; line-height: 1.45; text-decoration: none; color: #22568c; }
.prepared-lesson a:focus-visible, .prepared-lesson summary:focus-visible { outline: 3px solid #c37715; outline-offset: 3px; }
@media (max-width: 820px) {
  .slide.course-slide.prepared-lesson { width: calc(100vw - 20px); margin: 10px; padding: 22px 18px; }
  .prepared-lesson .lesson-toc, .prepared-lesson .lesson-cards { grid-template-columns: 1fr; }
  .prepared-lesson .lesson-content > table { font-size: 17px; }
  .prepared-lesson .lesson-content th, .prepared-lesson .lesson-content td { padding: 8px; overflow-wrap: anywhere; }
  .prepared-lesson .code-playground .play-editor textarea, .prepared-lesson .code-playground .play-colors { font-size: 18px; }
}