/* 第3—17课专用：借鉴代码优先、逐步揭示的演示思路，不引入外部字体/框架。 */
body { background: #e9eef5; }
.slide.course-slide { width: min(1440px, calc(100vw - 40px)); min-height: min(810px, calc((100vw - 40px) * .5625)); background: #fff; padding: 34px 48px 28px; border-top: 5px solid #215ab0; box-shadow: 0 10px 32px #233c5c16; overflow: visible; }
.slide::after, .slide:after { display: none; }
.slide-top { font-size: 16px; border-bottom: 1px solid #dce3ed; }
.eyebrow { margin: 24px 0 10px; color: #215ab0; font-size: 17px; }
.slide h2 { font-size: 38px; line-height: 1.25; margin: 12px 0 20px; color: #182d4c; }
.slide h3 { font-size: 25px; line-height: 1.45; }
.slide p, .slide li { line-height: 1.6; }
.slide .lead { font-size: 24px; color: #31435e; max-width: 100%; }
.slide .tip { background: #f2f6fc; border: 1px solid #d8e4f4; border-left: 4px solid #215ab0; color: #273d59; font-size: 21px; padding: 16px 20px; margin: 22px 0; }
.slide .card, .slide .step, .slide .reference-grid article { background: #f7f9fc; border: 1px solid #dce3ed; box-shadow: none; min-height: 0; border-radius: 12px; padding: 20px; }
.slide .card p, .slide .step p, .slide .check-list li { font-size: 21px; }
.slide .reference-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 18px; }
.slide .reference-grid article { border-top: 3px solid #215ab0; }
.slide .reference-grid article:nth-child(3n+2) { border-top-color: #0c746b; }
.slide .reference-grid article:nth-child(3n) { border-top-color: #996117; }
.slide .reference-grid p { font-size: 22px; }
.slide .reference-grid small { font-size: 18px; }
.review-goals { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 20px; margin: 30px 0; }
.review-goals article { padding: 24px; border-radius: 12px; background: #f2f6fc; border-top: 4px solid #215ab0; }
.review-goals article:nth-child(2) { background: #f0f8f6; border-color: #0c746b; }
.review-goals article:nth-child(3) { background: #fff8ee; border-color: #996117; }
.review-goals span { font-size: 28px; font-weight: 800; color: #215ab0; }
.review-goals p { font-size: 23px; margin-bottom: 0; }
.review-comparison { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 22px; }
.review-comparison article { min-width: 0; padding: 18px; background: #f7f9fc; border: 1px solid #dce3ed; border-radius: 12px; }
.review-comparison h3 { margin: 0 0 12px; }
.slide pre.code-reference { white-space: pre-wrap; overflow-wrap: anywhere; font: 21px/1.55 Consolas, monospace; color: #172e4b; background: #f7f9fc; border: 0; padding: 4px; margin: 0; min-height: 0; }
.review-answer { border: 1px solid #b8d7cf; background: #f2f9f6; border-radius: 10px; margin: 18px 0; padding: 0 20px; }
.review-answer summary { cursor: pointer; font-size: 21px; font-weight: 700; color: #155e50; padding: 15px 0; }
.review-answer p { font-size: 21px; margin: 0 0 18px; }
.review-assignment { padding: 24px 28px; border: 1px solid #dce3ed; border-left: 5px solid #215ab0; background: #f7f9fc; border-radius: 12px; }
.review-assignment p { font-size: 25px; }
.slide .option-grid article { min-height: 106px; border-width: 1px; align-items: flex-start; background: #f7f9fc; }
.slide .option-grid p { font-size: 22px; }
.slide .code { font-size: 21px; white-space: pre-wrap; overflow-wrap: anywhere; }
/* 导航回到正文流，清除各课旧版绝对定位留下的偏移。 */
.slide .page-nav {
  position: static;
  inset: auto;
  width: 100%;
  margin: 28px 0 0;
  padding-top: 16px;
  border-top: 1px solid #dce3ed;
  display: flex;
  justify-content: flex-end;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}
.slide .page-nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  white-space: nowrap;
}
.page-nav a, .lesson-index .toc a { text-underline-offset: 4px; }
a:focus-visible, summary:focus-visible, button:focus-visible { outline: 3px solid #215ab0; outline-offset: 4px; }
.code-playground .play-note { font-size: 17px; }
.code-playground .play-result iframe, .code-playground .play-placeholder { height: 340px; }
.lesson-index .toc a { display: block; padding: 9px 8px; border-bottom: 1px solid #e2e8f0; font-size: 19px; }
.slide .embedded-demo-wrap { height: 400px; }
@media (max-width: 820px) {
  .slide.course-slide { width: 100%; padding: 24px 20px; margin: 0; min-height: 100vh; }
  .review-goals, .review-comparison, .slide .reference-grid { grid-template-columns: 1fr; }
  .slide h2 { font-size: 30px; }
}
@media print { .slide.course-slide { width: 100%; box-shadow: none; min-height: 0; } .page-nav { display: none !important; } }