/* A full-width lesson player, with optional hands-on practice below. */
.concept-video { width: 100%; margin-top: 24px; color: #10233f; }
.concept-video video { display: block; width: 100%; max-width: 100%; height: auto; aspect-ratio: 16 / 9; object-fit: contain; background: #f4f7fc; border: 1px solid #dce6f1; border-radius: 8px; }
.concept-video video::cue { color: #fff; background: rgba(16, 35, 63, .84); font-family: "Noto Sans SC", sans-serif; font-size: clamp(14px, 1.35vw, 26px); }
.concept-video [hidden] { display: none !important; }
.concept-video-chapters { display: grid; grid-template-columns: repeat(5, minmax(0, 1fr)); gap: 0; margin-top: 16px; border-bottom: 1px solid #dce6f1; }
.concept-video-chapters button { display: grid; align-content: start; gap: 4px; min-width: 0; min-height: 100px; padding: 12px 12px 14px; color: #10233f; background: #fff; border: 0; border-bottom: 3px solid transparent; border-radius: 4px 4px 0 0; text-align: left; cursor: pointer; }
.concept-video-chapters small { color: #73869f; font: 500 11px/1.6 var(--mono); font-variant-numeric: tabular-nums; }
.concept-video-chapters strong { font-size: 14px; font-weight: 650; line-height: 1.6; }
.concept-video-chapters span { color: #596c85; font-size: 11px; line-height: 1.65; }
.concept-video-chapters button:hover { background: #f4f8fe; }
.concept-video-chapters button[aria-current="true"] { color: #0e51b4; background: #edf4ff; border-bottom-color: #1769e8; }
.concept-video-chapters button[aria-current="true"] small { color: #0e51b4; }
.concept-video-toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 20px; margin-top: 10px; }
.concept-video .concept-video-note { margin: 0 auto 0 0; color: #697a91; font-size: 12px; }
.concept-video-speed { display: flex; align-items: center; gap: 9px; color: #596c85; font-size: 12px; }
.concept-video-speed select { min-height: 44px; padding: 8px 25px 8px 10px; color: #315675; background-color: #fff; border: 1px solid #c7d7ea; border-radius: 6px; font: inherit; font-size: 13px; }
.concept-video-download { display: inline-flex; align-items: center; min-height: 44px; color: #315675; font-size: 12px; text-decoration: underline; text-underline-offset: 4px; }
.concept-video button:focus-visible, .concept-video select:focus-visible, .concept-video a:focus-visible, .concept-video video:focus-visible, .concept-lab-practice > summary:focus-visible { outline: 3px solid #1769e8; outline-offset: 4px; }
.concept-video .concept-video-error { margin-top: 14px; padding: 12px 16px; color: #795b2e; background: #fff8ea; border-left: 3px solid #b68b46; font-size: 13px; }
.concept-video-error a { color: inherit; text-decoration: underline; text-underline-offset: 3px; }
.concept-video-status { position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.concept-lab-practice { margin-top: 24px; border-top: 1px solid #dce6f1; }
.concept-lab-practice > summary { min-height: 58px; padding: 17px 4px; color: #315675; font-size: 14px; font-weight: 600; cursor: pointer; }
.concept-lab-practice > summary::marker { color: #1769e8; }
.concept-lab-practice[open] > summary { color: #0e51b4; }
.concept-lab-practice > .lab-challenges { margin-top: 4px; }
@container concept-lab (max-width: 760px) {
  .concept-video-chapters { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 1px; border: 0; background: #dce6f1; }
  .concept-video-chapters button { grid-template-columns: 42px 1fr; gap: 2px 8px; min-height: 69px; padding: 10px 12px; border: 0; border-left: 3px solid transparent; border-radius: 0; }
  .concept-video-chapters small { grid-row: span 2; align-self: start; padding-top: 2px; }
  .concept-video-chapters span { grid-column: 2; }
  .concept-video-chapters button:last-child { grid-column: 1 / -1; }
  .concept-video-chapters button[aria-current="true"] { border-left-color: #1769e8; }
}
@container concept-lab (max-width: 480px) {
  .concept-video { margin-top: 20px; }
  .concept-video video { border-radius: 5px; }
  .concept-video-chapters button { grid-template-columns: 1fr; gap: 2px; padding: 10px; }
  .concept-video-chapters small { grid-row: auto; }
  .concept-video-chapters span { grid-column: 1; }
  .concept-video-toolbar { gap: 6px 16px; }
  .concept-video .concept-video-note { width: 100%; margin-bottom: 2px; }
  .concept-video-download { margin-left: auto; }
}
@media (prefers-reduced-motion: reduce) {
  .concept-video *, .concept-lab-practice > summary { animation: none !important; transition: none !important; }
}