.is-learning [data-nav-region] { display: none; }
.is-learning .main { max-width: 1380px; padding: 24px 40px 64px; margin: 0 auto; }
.is-learning .app-header { background: #fff; backdrop-filter: none; }
.learning-page { --lesson-width: 760px; display: block; }
.learning-topline { display: flex; align-items: center; gap: 20px; font-size: 13px; color: var(--muted); min-height: 40px; }
.learning-topline > .btn { margin-left: auto; }
.learning-back { padding: 10px 0; background: none; color: var(--text); font-weight: 650; white-space: nowrap; }
.learning-back:hover { color: var(--accent); }
.learning-heading { padding: 28px 0 32px; max-width: 920px; }
.learning-eyebrow { margin: 0 0 12px; font-size: 11px; line-height: 1.5; font-weight: 750; letter-spacing: .13em; color: var(--muted); }
.learning-heading h1 { margin: 0; font-size: clamp(28px, 3vw, 42px); line-height: 1.15; letter-spacing: -.035em; overflow-wrap: anywhere; }
.learning-heading > p:last-child:not(.learning-eyebrow) { margin: 14px 0 0; font-size: 16px; line-height: 1.6; color: var(--muted); max-width: 72ch; }
.learning-layout { display: grid; grid-template-columns: 258px minmax(0,1fr); gap: 40px; align-items: start; }
.learning-sidebar { position: sticky; top: 104px; }
.learning-curriculum { padding: 0; border: 1px solid var(--line); border-radius: 14px; background: #fff; overflow: hidden; }
.learning-curriculum summary { padding: 20px; font-weight: 700; font-size: 14px; cursor: pointer; }
.learning-curriculum summary span { float: right; font-weight: 500; color: var(--muted); font-variant-numeric: tabular-nums; }
.learning-progress { margin: 0 20px 16px; padding-top: 4px; }
.learning-progress > div { display: flex; justify-content: space-between; color: var(--muted); font-size: 12px; margin-bottom: 10px; }
.learning-progress strong { color: var(--accent); }
.learning-progress progress { display: block; appearance: none; width: 100%; height: 5px; border: 0; border-radius: 4px; overflow: hidden; background: var(--surface-soft); }
.learning-progress progress::-webkit-progress-bar { background: var(--surface-soft); }
.learning-progress progress::-webkit-progress-value { background: var(--accent); border-radius: 4px; }
.learning-progress progress::-moz-progress-bar { background: var(--accent); }
.learning-step { display: flex; width: 100%; align-items: flex-start; gap: 12px; padding: 16px 18px; text-align: left; color: var(--text); background: transparent; border-left: 3px solid transparent; border-radius: 0; min-height: 76px; }
.learning-step:hover { background: #f7f9fc; }
.learning-step.is-current { background: var(--accent-soft); border-left-color: var(--accent); }
.learning-step-number { flex: 0 0 24px; width: 24px; padding-top: 1px; color: var(--muted); font-size: 12px; font-weight: 650; font-variant-numeric: tabular-nums; }
.learning-step.is-current .learning-step-number, .learning-step.is-done .learning-step-number { color: var(--accent); }
.learning-step strong { display: block; font-weight: 620; line-height: 1.5; font-size: 13px; overflow-wrap: anywhere; }
.learning-step small { display: block; margin-top: 4px; color: var(--muted); line-height: 1.5; font-size: 11px; }
.learning-final { border-top: 1px solid var(--line); }
.learning-save-note { color: var(--muted); font-size: 11px; text-align: center; line-height: 1.5; margin: 14px 4px; }
.learning-stage { min-width: 0; background: #fff; border: 1px solid var(--line); border-radius: 16px; overflow: hidden; min-height: 460px; }
.learning-lesson-heading { padding: 36px 40px 28px; border-bottom: 1px solid var(--line); }
.learning-lesson-heading h2 { margin: 0; font-size: clamp(24px,2.2vw,32px); line-height: 1.25; letter-spacing: -.025em; overflow-wrap: anywhere; scroll-margin-top: 120px; }
.learning-lesson-heading > p { color: var(--muted); font-size: 15px; line-height: 1.6; margin: 14px 0 0; }
.learning-content { padding: 8px 40px 32px; max-width: 100%; }
.learning-content .material-block { padding: 28px 0; margin: 0; border: 0; border-radius: 0; box-shadow: none; background: transparent; overflow-wrap: anywhere; }
.learning-content .material-block + .material-block { border-top: 1px solid #edf0f3; }
.learning-content .material-block h4 { margin: 0 0 16px; font-size: 20px; line-height: 1.4; letter-spacing: -.015em; }
.learning-content .rich-content { font-size: 16px; line-height: 1.8; max-width: 72ch; color: #273440; }
.learning-content .rich-content > :first-child { margin-top: 0; }
.learning-content .rich-content > :last-child { margin-bottom: 0; }
.learning-content .rich-content p { margin: 0 0 18px; }
.learning-content .rich-content li { margin: 7px 0; }
.learning-content .note-block { padding: 24px; margin: 20px 0; border-left: 3px solid var(--accent); background: #f4f8ff; border-radius: 0 8px 8px 0; }
.learning-content .material-image { max-width: 100%; width: auto; max-height: 600px; object-fit: contain; border-radius: 8px; }
.learning-content .material-frame { width: 100%; aspect-ratio: 16/9; border: 1px solid var(--line); }
.learning-content .material-block > .btn, .learning-content .material-block > .pill { margin-top: 20px; font-size: 12px; }
.learning-content .material-block > .btn { background: transparent; border-color: var(--line); color: var(--muted); }
.learning-lesson-footer { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; padding: 24px 40px; background: #fafbfd; border-top: 1px solid var(--line); }
.learning-lesson-footer > div { display: flex; flex-direction: column; align-items: flex-end; gap: 10px; min-width: 0; }
.learning-lesson-footer small { font-size: 12px; color: var(--muted); text-align: right; overflow-wrap: anywhere; }
.learning-page .btn { min-height: 42px; border-radius: 8px; line-height: 1.35; white-space: normal; }
.learning-page .btn.primary { padding: 12px 20px; background: var(--accent); box-shadow: none; }
.learning-page .btn.primary:hover:not(:disabled) { background: var(--accent-strong); }
.learning-assessments { padding: 8px 40px 36px; }
.learning-assessment { padding: 26px 0; }
.learning-assessment + .learning-assessment { border-top: 1px solid var(--line); }
.learning-test-label { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 10px; font-size: 12px; color: var(--muted); }
.learning-test-label span { color: var(--accent-strong); }
.learning-assessment h3 { font-size: 22px; letter-spacing: -.02em; margin: 20px 0 10px; overflow-wrap: anywhere; }
.learning-assessment > p { font-size: 15px; line-height: 1.65; color: var(--muted); }
.learning-test-facts { display: flex; flex-wrap: wrap; gap: 20px 40px; margin: 24px 0 28px; }
.learning-test-facts dt { font-size: 12px; color: var(--muted); }
.learning-test-facts dd { font-size: 16px; font-weight: 650; margin: 8px 0 0; }
.learning-empty { padding: 36px 0; color: var(--muted); line-height: 1.7; }
.learning-empty h3 { color: var(--text); font-size: 20px; margin: 0 0 10px; }
.learning-empty p { margin: 0 0 24px; }
button:focus-visible, a:focus-visible, summary:focus-visible, input:focus-visible, select:focus-visible, textarea:focus-visible, [contenteditable]:focus-visible { outline: 3px solid #2563eb; outline-offset: 3px; }
.learning-stage h2:focus { outline: none; }
@media (max-width: 1100px) {
  .is-learning .main { padding: 20px 24px 48px; }
  .learning-layout { grid-template-columns: 220px minmax(0,1fr); gap: 24px; }
  .learning-lesson-heading { padding: 28px; }
  .learning-content { padding: 0 28px 24px; }
  .learning-lesson-footer { padding: 22px 28px; }
  .learning-assessments { padding: 0 28px 28px; }
}
@media (max-width: 760px) {
  .is-learning .app-header { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 12px 16px; min-height: 64px; }
  .is-learning .header-stats, .is-learning .brand-home-button > span:last-child, .is-learning .compact-user > span { display: none; }
  .is-learning .header-actions { gap: 8px; }
  .is-learning .compact-user { max-width: 150px; min-height: 40px; }
  .is-learning .compact-user strong { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
  .is-learning .main { padding: 12px 16px 32px; }
  .learning-topline { gap: 12px; font-size: 11px; flex-wrap: wrap; }
  .learning-heading { padding: 22px 0 24px; }
  .learning-heading > p:last-child:not(.learning-eyebrow) { font-size: 14px; }
  .learning-layout { grid-template-columns: minmax(0,1fr); gap: 18px; }
  .learning-sidebar { position: static; }
  .learning-curriculum summary { padding: 16px; }
  .learning-save-note { display: none; }
  .learning-stage { border-radius: 12px; }
  .learning-lesson-heading { padding: 24px 20px; }
  .learning-content { padding: 0 20px 20px; }
  .learning-content .rich-content { font-size: 15px; line-height: 1.75; }
  .learning-content .note-block { padding: 20px 16px; }
  .learning-lesson-footer { padding: 20px; gap: 12px; align-items: stretch; flex-direction: column-reverse; }
  .learning-lesson-footer > div { align-items: stretch; }
  .learning-lesson-footer small { text-align: left; }
  .learning-lesson-footer .btn { width: 100%; }
  .learning-assessments { padding: 0 20px 24px; }
  .learning-assessment .actions { align-items: stretch; flex-direction: column; }
  .learning-test-facts { gap: 20px 28px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; }
}

/* Reading surface: light paper and charcoal share one layout and contrast scale. */
body[data-learning-theme="light"], body[data-learning-theme="dark"] {
  --lesson-bg: #fbfbfc;
  --lesson-surface: #f0f1f4;
  --lesson-hover: #e8ebf0;
  --lesson-ink: #24262d;
  --lesson-muted: #626570;
  --lesson-line: #d7d9df;
  --lesson-accent: #2855bd;
  --lesson-selected: #e5ecff;
  --lesson-success: #21613b;
  --lesson-error: #a42f32;
  background: var(--lesson-bg);
  color: var(--lesson-ink);
}
body[data-learning-theme="dark"] {
  --lesson-bg: #202124;
  --lesson-surface: #2b2d31;
  --lesson-hover: #36383e;
  --lesson-ink: #ededf0;
  --lesson-muted: #b0b2bc;
  --lesson-line: #484b54;
  --lesson-accent: #a6bdff;
  --lesson-selected: #303e60;
  --lesson-success: #9cddaf;
  --lesson-error: #ffb3b6;
}
.is-learning {
  --text: var(--lesson-ink);
  --muted: var(--lesson-muted);
  --line: var(--lesson-line);
  --accent: var(--lesson-accent);
  --accent-soft: var(--lesson-selected);
  background: var(--lesson-bg);
  min-height: 100vh;
  color: var(--lesson-ink);
}
.is-learning .main { max-width: 1260px; padding: 20px 44px 96px; }
.is-learning .app-header { background: var(--lesson-bg); border-bottom: 1px solid var(--lesson-line); box-shadow: none; }
.is-learning .header-stats { display: none; }
.is-learning .user-chip, .is-learning .app-header .btn, .is-learning .notification-bell { background: var(--lesson-surface); color: var(--lesson-ink); border-color: var(--lesson-line); box-shadow: none; }
.is-learning .brand-home-button { color: var(--lesson-ink); }
.learning-topline { font-size: 13px; }
.learning-topline > .btn { margin-left: 0; }
.learning-theme-toggle { margin-left: auto; padding: 10px 12px; min-height: 44px; background: transparent; color: var(--lesson-muted); border: 1px solid var(--lesson-line); border-radius: 8px; font-size: 12px; }
.learning-theme-toggle:hover { background: var(--lesson-hover); color: var(--lesson-ink); }
.learning-heading { padding: 20px 0 34px; max-width: 850px; }
.learning-heading h1 { font-size: 19px; font-weight: 550; line-height: 1.45; letter-spacing: -.01em; color: var(--lesson-muted); }
.learning-heading > p:last-child { font-size: 14px; margin-top: 8px; }
.learning-layout { grid-template-columns: 246px minmax(0, 760px); gap: 56px; }
.learning-curriculum { background: transparent; border: 0; border-radius: 0; }
.learning-curriculum summary { padding: 12px 0 22px; }
.learning-progress { margin: 0 0 20px; }
.learning-progress progress { color: var(--lesson-accent); }
.learning-progress progress::-webkit-progress-bar { background: var(--lesson-line); }
.learning-progress progress::-webkit-progress-value { background: var(--lesson-accent); }
.learning-step { border-left: 0; border-radius: 8px; padding: 14px 12px; margin-bottom: 4px; min-height: 68px; }
.learning-step:hover:not(:disabled) { background: var(--lesson-hover); }
.learning-step.is-current { background: var(--lesson-surface); }
.learning-step:disabled { opacity: .65; cursor: not-allowed; }
.learning-step strong { font-weight: 500; font-size: 13px; }
.learning-final { border-top: 1px solid var(--lesson-line); border-radius: 0; margin-top: 16px; padding-top: 24px; }
.learning-save-note { text-align: left; margin-left: 12px; }
.learning-stage { background: transparent; border: 0; border-radius: 0; overflow: visible; }
.learning-lesson-heading { padding: 8px 0 30px; border: 0; }
.learning-lesson-position { color: var(--lesson-muted); font-size: 13px; margin-bottom: 24px; }
.learning-lesson-heading h2 { font-size: clamp(28px, 3vw, 42px); font-weight: 650; line-height: 1.2; letter-spacing: -.025em; }
.learning-content { padding: 0; }
.learning-content .material-block { padding: 14px 0 24px; }
.learning-content .material-block + .material-block { border: 0; }
.learning-content .material-block h4 { font-size: 25px; line-height: 1.3; margin-top: 24px; }
.learning-content .rich-content { font-size: 17px; line-height: 1.8; color: var(--lesson-ink); }
.learning-content .material-block p, .learning-content .rich-content li, .learning-content .rich-content blockquote { color: var(--lesson-ink); }
.learning-content .rich-content a { color: var(--lesson-accent); text-decoration: underline; }
.learning-content .rich-content img { max-width: 100%; height: auto; }
.learning-content .note-block { background: var(--lesson-selected); border: 0; border-radius: 12px; padding: 24px 28px; margin: 16px 0 32px; }
.learning-content .material-block > .pill { background: transparent; border: 0; padding: 0; color: var(--lesson-success); }
.learning-content .material-block > .btn { color: var(--lesson-muted); }
.learning-lesson-footer { margin-top: 40px; padding: 28px 0; background: transparent; }
.learning-page .btn.primary { background: var(--lesson-ink); color: var(--lesson-bg); border: 1px solid transparent; }
.learning-page .btn.primary:hover:not(:disabled) { background: var(--lesson-ink); opacity: .85; }
.learning-page .btn.secondary, .learning-page .btn.ghost { background: transparent; color: var(--lesson-ink); border-color: var(--lesson-line); box-shadow: none; }
.learning-page .btn:disabled { opacity: .5; cursor: not-allowed; }
.learning-page :focus-visible { outline-color: var(--lesson-accent); }
.learning-assessments { padding: 0 0 36px; }
.learning-test-label span { color: var(--lesson-accent); }
.learning-gate { padding: 24px 0; border-top: 1px dashed var(--lesson-line); margin-top: 24px; color: var(--lesson-muted); font-size: 14px; line-height: 1.6; }
.learning-gate strong { font-weight: 550; }
.learning-gate p { margin-bottom: 0; }
.learning-exercise { margin: 32px 0; padding: 28px; background: var(--lesson-surface); border-radius: 14px; overflow-wrap: anywhere; }
.exercise-heading { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px 20px; color: var(--lesson-muted); font-size: 12px; line-height: 1.5; }
.learning-exercise h3 { margin: 24px 0 16px; font-size: 22px; line-height: 1.4; font-weight: 600; letter-spacing: -.015em; }
.exercise-prompt, .exercise-instruction { font-size: 15px; line-height: 1.65; white-space: pre-line; }
.exercise-instruction { color: var(--lesson-muted); }
.exercise-options { border: 0; padding: 0; margin: 24px 0 12px; display: grid; gap: 10px; min-width: 0; }
.exercise-option { display: flex; align-items: flex-start; gap: 14px; padding: 16px; border: 1px solid var(--lesson-line); border-radius: 8px; cursor: pointer; line-height: 1.6; font-size: 15px; color: var(--lesson-ink); }
.exercise-option:hover { background: var(--lesson-hover); }
.exercise-option.is-selected { background: var(--lesson-selected); border-color: var(--lesson-accent); }
.exercise-option input { flex: 0 0 18px; width: 18px; height: 18px; margin: 3px 0 0; accent-color: var(--lesson-accent); }
.exercise-feedback { font-size: 14px; line-height: 1.6; white-space: pre-line; }
.exercise-feedback:not(:empty) { margin: 20px 0; }
.exercise-feedback.error { color: var(--lesson-error); }
.exercise-feedback.success { color: var(--lesson-success); }
.learning-exercise.is-complete { background: transparent; border: 1px solid var(--lesson-line); }
.learning-exercise.is-complete .exercise-heading span:last-child { color: var(--lesson-success); }
.matching-board { position: relative; display: grid; grid-template-columns: minmax(0,1fr) minmax(0,1fr); gap: 64px; margin: 24px 0 16px; }
.matching-column { display: grid; gap: 14px; align-content: start; min-width: 0; }
.matching-item { position: relative; display: flex; align-items: center; gap: 8px; width: 100%; min-height: 64px; padding: 14px 10px; background: var(--lesson-bg); color: var(--lesson-ink); border: 1px solid var(--lesson-line); border-radius: 8px; text-align: left; font-size: 14px; line-height: 1.5; overflow-wrap: anywhere; }
.matching-item > span:not(.match-port):not(.match-number) { min-width: 0; flex: 1; }
.matching-item:hover { background: var(--lesson-hover); }
.matching-item.is-selected { outline: 2px solid var(--lesson-accent); outline-offset: 3px; }
.matching-item.is-connected { border-color: var(--lesson-accent); background: var(--lesson-selected); }
.match-number { font-size: 11px; font-weight: 600; min-width: 12px; color: var(--lesson-muted); }
.match-port { position: absolute; width: 8px; height: 8px; border: 1px solid var(--lesson-accent); border-radius: 50%; background: var(--lesson-bg); }
.matching-column:first-of-type .match-port { right: -5px; }
.matching-column:last-of-type .match-port { left: -5px; }
.matching-lines { position: absolute; inset: 0; width: 100%; height: 100%; overflow: visible; pointer-events: none; color: var(--lesson-accent); }
.matching-lines g path { fill: none; stroke: currentColor; stroke-width: 1.7; }
.matching-status { font-size: 13px; color: var(--lesson-muted); line-height: 1.6; }
.exercise-editor { display: grid; gap: 16px; margin-top: 16px; }
.exercise-editor-help { font-size: 13px; line-height: 1.6; color: var(--muted); margin: 0; }
.exercise-editor-row { display: flex; align-items: center; gap: 12px; }
.exercise-editor-row label { flex: 1; min-width: 0; font-size: 12px; }
.exercise-editor-row label input { margin-top: 6px; width: 100%; }
.exercise-editor-row > input { width: 18px; height: 18px; flex: 0 0 18px; }
.exercise-editor .field { margin: 0; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }
@media (max-width: 1100px) {
  .learning-layout { grid-template-columns: 210px minmax(0,1fr); gap: 32px; }
  .is-learning .main { padding: 20px 28px 64px; }
  .learning-exercise { padding: 24px; }
  .matching-board { gap: 48px; }
}
@media (max-width: 760px) {
  .is-learning .main { padding: 12px 20px 48px; }
  .learning-topline { gap: 8px; }
  .learning-topline > span { display: none; }
  .learning-theme-toggle { font-size: 11px; }
  .learning-heading { padding: 16px 0 20px; }
  .learning-heading h1 { font-size: 16px; }
  .learning-heading > p { display: none; }
  .learning-layout { grid-template-columns: minmax(0,1fr); gap: 24px; }
  .learning-curriculum { border-bottom: 1px solid var(--lesson-line); }
  .learning-curriculum summary { padding: 12px 0 18px; }
  .learning-lesson-heading { padding: 0 0 24px; }
  .learning-lesson-position { margin-bottom: 16px; }
  .learning-lesson-heading h2 { font-size: 30px; }
  .learning-content .rich-content { font-size: 16px; line-height: 1.8; }
  .learning-content .note-block { padding: 20px; }
  .learning-exercise { padding: 20px 16px; margin: 28px -4px; }
  .learning-exercise h3 { font-size: 20px; }
  .exercise-option { padding: 14px 12px; font-size: 14px; }
  .exercise-heading { font-size: 11px; }
  .matching-board { gap: 36px; }
  .matching-item { padding: 12px 8px; font-size: 13px; min-height: 76px; gap: 4px; }
  .matching-item .match-number { font-size: 10px; }
  .learning-lesson-footer { padding: 24px 0; }
  .exercise-editor-row { gap: 6px; }
}