/* 第四课局部样式，不改变其他课程。 */
.prepared-lesson .lesson-content { flex: 1; min-width: 0; }
.prepared-lesson .lesson-cards { display: grid; grid-template-columns: repeat(auto-fit,minmax(240px,1fr)); gap: 18px; margin: 20px 0; }
.prepared-lesson .lesson-cards article { background:#f2f7ff; border:1px solid #d5e0ef; border-top:4px solid #2563a5; border-radius:12px; padding:20px; }
.prepared-lesson .lesson-cards article:nth-child(2n) { background:#f0f8f5; border-top-color:#168174; }
.prepared-lesson .lesson-cards article:nth-child(3n) { background:#fbf5ed; border-top-color:#b06b1c; }
.prepared-lesson .lesson-content p, .prepared-lesson .lesson-content li { font-size:22px; }
.prepared-lesson .lesson-cards h3 { margin:0 0 12px; }
.prepared-lesson .lesson-cards p { margin:0; }
.prepared-lesson table { width:100%; border-collapse:collapse; font-size:21px; margin:18px 0; }
.prepared-lesson th, .prepared-lesson td { padding:12px 16px; border:1px solid #cdd9e6; text-align:left; }
.prepared-lesson th { background:#eaf1fa; }
.prepared-lesson .assignment { padding:18px 24px; background:#f5f2fc; border-left:4px solid #7753a9; border-radius:8px; margin:20px 0; }
.prepared-lesson .assignment h3 { margin:0 0 8px; }
.prepared-lesson .assignment p { margin:0; }
.prepared-lesson .answer { border:1px solid #c8ddda; border-radius:10px; padding:16px 22px; background:#f1f8f6; margin-top:16px; }
.prepared-lesson .answer summary { cursor:pointer; font-size:21px; font-weight:700; color:#166659; }
.prepared-lesson .answer p { margin-bottom:0; }
.prepared-lesson .lesson-toc { display:grid; grid-template-columns:repeat(3,minmax(0,1fr)); gap:10px 22px; }
.prepared-lesson .lesson-toc a { font-size:20px; padding:10px 0; border-bottom:1px solid #dce3ed; text-decoration:none; color:#22568c; }
.prepared-lesson .url { font-size:18px; overflow-wrap:anywhere; }
.prepared-lesson .full-demo { width:100%; height:490px; border:1px solid #cdd9e6; border-radius:10px; }
.prepared-lesson .demo-link { display:inline-block; padding:12px 18px; background:#eaf1fa; border-radius:8px; }
.prepared-lesson .code-playground .play-editor textarea, .prepared-lesson .code-playground .play-colors { font-size:22px; line-height:1.5; }
.prepared-lesson .code-playground p.play-note { font-size:16px; line-height:1.5; margin:8px 0; }
.prepared-lesson .page-nav { position:static; margin-top:28px; justify-content:space-between; }
.stacked-code .code-playground { grid-template-columns:1fr !important; }
.stacked-code .code-playground .play-editor, .stacked-code .code-playground .play-result { grid-column:1 / -1 !important; grid-row:auto !important; }
@media(max-width:820px) {
 .prepared-lesson .lesson-toc, .prepared-lesson .lesson-cards { grid-template-columns:1fr; }
 .prepared-lesson .table-scroll { overflow-x:auto; }
 .prepared-lesson th, .prepared-lesson td { padding:8px; font-size:17px; overflow-wrap:anywhere; }
 .prepared-lesson .code-playground .play-editor textarea, .prepared-lesson .code-playground .play-colors { font-size:18px; }
}