/* Classroom layout: preserve all content, then fit the whole lesson to the viewport. */
@media (min-width: 1000px) {
  html.lesson-desktop, .lesson-desktop body { margin: 0; padding: 0; min-height: 0; }
  .lesson-desktop .app {
    box-sizing: border-box; min-height: 0 !important; max-width: none !important;
    grid-template-columns: minmax(0, 1fr) 250px !important;
    align-items: start; gap: 12px !important; padding: 10px !important;
    margin: 8px auto !important;
  }
  .lesson-desktop .workspace { min-height: 0 !important; min-width: 0 !important; padding: 8px !important; }
  .lesson-desktop .lab-viewport { width: auto !important; height: auto !important; }
  .lesson-desktop .lab-viewport > .lab-card { transform: none !important; }
  .lesson-desktop .app > .notes {
    display: block !important; position: static !important; max-height: none !important;
    height: auto !important; overflow: visible !important; margin: 0 !important; padding: 16px !important;
  }
  .lesson-desktop .app > .notes h2 { margin: 0 0 14px; }
  .lesson-desktop .app > .notes h3 { margin: 16px 0 7px; }
  .lesson-desktop .app > .notes .principle { margin-top: 14px; }
  .lesson-desktop .lesson-home-close { width: 42px; height: 42px; font-size: 30px; box-shadow: 0 5px 12px #f24b5b25; }
  .lesson-desktop .app:has(.function-list) { grid-template-columns: minmax(0, 1fr) 360px !important; }
  .lesson-desktop .app > .panel { max-height: none !important; overflow: visible !important; }
  .lesson-desktop .app:has(.function-list) .lab { height: auto !important; grid-template-rows: auto minmax(640px, 1fr) auto; }
  .lesson-desktop .app:has(.function-list) .below { height: auto; }
  .lesson-desktop .app:has(.function-list) .intersections { max-height: none; overflow: visible; }

  .lesson-desktop .lesson-fluid .heading { padding: 12px 76px 8px 18px; gap: 12px; }
  .lesson-desktop .lesson-fluid .heading h1 { font-size: 23px; }
  .lesson-desktop .lesson-fluid .mode-tabs { padding: 4px 16px 10px; gap: 7px; }
  .lesson-desktop .lesson-fluid .mode-tabs button { min-height: 34px; padding: 7px 12px; }
  .lesson-desktop .lesson-fluid .lesson-body { display: grid; grid-template-columns: minmax(0, 1fr) 310px !important; }
  .lesson-desktop .lesson-fluid .board-tools { padding: 8px 16px 0; min-height: 36px; }
  .lesson-desktop .lesson-fluid .stage-caption { min-height: 26px; padding: 6px 18px 0; }
  .lesson-desktop .lesson-fluid .board-wrap { padding-bottom: 10px; }
  .lesson-desktop .lesson-fluid .drag-hint { min-height: 0; padding: 6px 18px; }
  .lesson-desktop .lesson-fluid .parameter-box { margin: 6px 16px 0; padding: 5px 10px; }
  .lesson-desktop .lesson-fluid .relation-strip { margin: 0 14px; padding: 10px; min-height: 0; gap: 8px; grid-template-columns: 75px 1fr; }
  .lesson-desktop .lesson-fluid .relation-pill { padding: 5px 8px; font-size: 14px; }
  .lesson-desktop .lesson-fluid .relation-list { gap: 6px; }
  .lesson-desktop .lesson-fluid .panel { display: flex !important; flex-direction: column; border-left: 1px solid #e7ecf0; border-top: 0; padding: 14px; gap: 0; }
  .lesson-desktop .lesson-fluid .panel h2 { margin: 0 0 8px; }
  .lesson-desktop .lesson-fluid .redline { margin-bottom: 10px; flex-shrink: 0; }
  .lesson-desktop .lesson-fluid .info-box { padding: 10px; margin: 0 0 8px; }
  .lesson-desktop .lesson-fluid .info-box h3 { margin-bottom: 5px; }
  .lesson-desktop .lesson-fluid .info-box p { font-size: 15px; line-height: 1.65; }
  .lesson-desktop .lesson-fluid .data-row { padding: 5px 0; }
  .lesson-desktop .lesson-fluid .step-box { min-height: 190px; }
  .lesson-desktop .lesson-fluid .step-count { margin-bottom: 5px; }
  .lesson-desktop .lesson-fluid .equation { margin-top: 8px; padding: 8px 6px; min-height: 0; line-height: 1.6; }
  .lesson-desktop .lesson-fluid .progress { margin-top: 9px; }
  .lesson-desktop .lesson-fluid .controls { display: grid; grid-template-columns: 1fr 1fr; gap: 7px; margin-top: 2px; }
  .lesson-desktop .lesson-fluid .controls button { min-height: 36px; padding: 8px 4px; }
  .lesson-desktop .lesson-fluid .controls .wide { grid-column: auto; }
  .lesson-desktop .lesson-fluid .formula-review { margin: 0 14px 10px; padding: 10px; }
  .lesson-desktop .lesson-fluid .formula-review h2 { margin-bottom: 7px; }
  .lesson-desktop .lesson-fluid .review-grid p { padding: 8px; }
}