/* Shared by the lesson reader and its self-contained HTML download. */
.lesson-studio {
  --lesson-blue: #126fc4;
  --lesson-ink: #1f242c;
  --lesson-muted: #526171;
  --lesson-line: #dde3ea;
  --lesson-mist: #eaf4ff;
  width: 100%; max-width: 1180px; margin-inline: auto; padding: 32px 40px 56px;
  background: #fff; color: var(--lesson-ink); border-radius: 24px;
  font: 500 15px/1.6 "Manrope", system-ui, sans-serif;
  overflow-wrap: anywhere;
}
.lesson-studio *, .lesson-studio *::before, .lesson-studio *::after { box-sizing: border-box; }
.lesson-studio h1, .lesson-studio h2, .lesson-studio h3, .lesson-studio p { margin: 0; }
.lesson-studio h1, .lesson-studio h2, .lesson-studio h3 { color: var(--lesson-ink); }
.lesson-studio a { color: inherit; text-decoration: none; }
.lesson-studio .study-notes a { color: var(--lesson-blue); text-decoration: underline; text-underline-offset: 3px; }
.lesson-studio button, .lesson-studio input, .lesson-studio textarea { font: inherit; }
.lesson-studio :is(a, button, summary, input, textarea, select):focus-visible { outline: 3px solid var(--lesson-blue); outline-offset: 4px; }
.lesson-studio :is(section, details, #explanation) { scroll-margin-top: 28px; }
.lesson-studio .lesson-toolbar { justify-content: space-between; gap: 16px; margin: 0 0 44px; color: var(--lesson-muted); font-size: 12px; }
.lesson-studio .lesson-toolbar > a { color: var(--lesson-ink); font-weight: 700; }
.lesson-tools { flex-shrink: 0; }
.lesson-studio .lesson-toolbar .lesson-actions-trigger { anchor-name: --lesson-actions; display: grid; place-items: center; width: 44px; height: 44px; border: 1px solid var(--lesson-line); border-radius: 50%; color: var(--lesson-ink); background: #fff; transition: background 150ms ease, transform 150ms ease; }
.lesson-actions-trigger:active { transform: scale(.96); }
.lesson-actions-menu { position-anchor: --lesson-actions; position: fixed; inset: auto; top: anchor(bottom); right: anchor(right); position-try-fallbacks: flip-block; margin: 8px 0 0; width: 220px; max-width: calc(100vw - 32px); padding: 6px; border: 1px solid var(--lesson-line); border-radius: 16px; background: white; color: var(--lesson-ink); box-shadow: 0 12px 40px rgb(31 36 44 / 12%), 0 2px 8px rgb(31 36 44 / 4%); }
@supports not (top: anchor(bottom)) { .lesson-actions-menu { inset: 110px 24px auto auto; } }
.lesson-studio .lesson-toolbar .lesson-actions-menu :is(a, button) { display: flex; align-items: center; gap: 12px; width: 100%; min-height: 44px; padding: 10px 12px; border: 0; border-radius: 10px; background: transparent; color: var(--lesson-ink); font-size: 13px; font-weight: 600; text-align: left; cursor: pointer; }
.lesson-actions-menu svg { flex-shrink: 0; color: var(--lesson-muted); }
.lesson-studio .lesson-toolbar .lesson-actions-menu button:last-child { margin-top: 4px; border-top: 1px solid var(--lesson-line); border-radius: 0 0 10px 10px; color: var(--lesson-blue); }
.lesson-actions-menu button:last-child svg { color: inherit; }
.lesson-share-dialog { width: min(460px, calc(100% - 32px)); max-height: calc(100dvh - 32px); margin: auto; padding: 28px; overflow-y: auto; border: 1px solid var(--lesson-line); border-radius: 24px; background: white; color: var(--lesson-ink); box-shadow: 0 24px 80px rgb(31 36 44 / 18%); }
.lesson-share-dialog::backdrop { background: rgb(31 36 44 / 36%); backdrop-filter: blur(4px); }
.lesson-share-heading { display: flex; justify-content: space-between; align-items: start; margin-bottom: 20px; }
.lesson-share-icon { display: grid; place-items: center; width: 48px; height: 48px; border-radius: 16px; background: var(--lesson-mist); color: var(--lesson-blue); }
.lesson-share-close { display: grid; place-items: center; width: 44px; height: 44px; margin: -8px -8px 0 0; border: 0; border-radius: 50%; background: transparent; color: var(--lesson-muted); cursor: pointer; }
.lesson-studio .lesson-share-dialog h2 { max-width: 17ch; font: 400 32px/1.12 Georgia, "Times New Roman", serif; letter-spacing: -.035em; }
.lesson-studio .lesson-share-dialog turbo-frame > p { margin-top: 12px; color: var(--lesson-muted); font-size: 13px; line-height: 1.7; }
.lesson-share-preview { display: grid; gap: 6px; margin: 24px 0; padding: 20px; border: 1px solid var(--lesson-line); border-radius: 14px; background: #f8fafc; }
.lesson-share-preview > span { color: var(--lesson-blue); font-size: 10px; font-weight: 800; letter-spacing: .1em; }
.lesson-share-preview strong { font: 400 22px/1.3 Georgia, "Times New Roman", serif; }
.lesson-share-preview small { color: var(--lesson-muted); font-size: 12px; }
.lesson-share-dialog label { display: block; margin-bottom: 8px; font-size: 12px; font-weight: 700; }
.lesson-share-link { display: flex; gap: 8px; }
.lesson-share-link input { width: 100%; min-width: 0; padding: 12px; border: 1px solid var(--lesson-line); border-radius: 10px; background: #f8fafc; color: var(--lesson-muted); font-size: 12px; text-overflow: ellipsis; }
.lesson-share-dialog .button { min-height: 44px; padding: 12px 16px; border: 0; border-radius: 10px; background: var(--lesson-blue); color: white; font-size: 12px; font-weight: 700; white-space: nowrap; cursor: pointer; }
.lesson-share-dialog form { margin: 0; }
.lesson-share-enable { width: 100%; }
.lesson-share-footer { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 12px; font-size: 12px; }
.lesson-share-footer a { display: inline-flex; align-items: center; min-height: 44px; color: var(--lesson-blue); }
.lesson-share-footer .link-button { min-height: 44px; padding: 0; border: 0; background: transparent; color: var(--lesson-muted); font-size: 12px; cursor: pointer; }
.lesson-studio .lesson-share-dialog .lesson-share-privacy { display: flex; align-items: center; gap: 8px; margin-top: 20px; padding-top: 16px; border-top: 1px solid var(--lesson-line); font-size: 11px; }
.lesson-share-privacy svg { flex-shrink: 0; }
@media (hover: hover) and (pointer: fine) {
  .lesson-studio .lesson-toolbar .lesson-actions-trigger:hover, .lesson-studio .lesson-toolbar .lesson-actions-menu :is(a, button):hover, .lesson-share-close:hover { background: #f1f5f9; }
  .lesson-share-dialog .button:hover { background: #0d5faa; }
}
@media (max-width: 600px) { .lesson-share-dialog { padding: 24px; border-radius: 20px; } }
@media (prefers-reduced-motion: reduce) { .lesson-actions-trigger { transition: none; } }
.lesson-context { display: flex; align-items: center; flex-wrap: wrap; gap: 8px 20px; margin-bottom: 24px; color: var(--lesson-muted); font-size: 12px; }
.lesson-context > span:first-child { color: var(--lesson-blue); font-weight: 800; }
.lesson-context > span + span { border-left: 1px solid var(--lesson-line); padding-left: 20px; }
.lesson-studio .lesson-masthead h1 { max-width: 20ch; font: 400 clamp(2.8rem, 4.6vw, 4.5rem)/1.08 Georgia, "Times New Roman", serif; letter-spacing: -.045em; text-wrap: balance; }
.lesson-outcome { display: flex; align-items: baseline; gap: 20px; max-width: 76ch; margin: 26px 0 32px; }
.lesson-outcome > span { flex-shrink: 0; color: var(--lesson-blue); font-size: 12px; font-weight: 800; }
.lesson-studio .lesson-outcome p { color: var(--lesson-muted); font-size: 14px; line-height: 1.6; }
.lesson-modes { display: flex; flex-wrap: wrap; gap: 8px; padding-bottom: 30px; margin-bottom: 40px; border-bottom: 1px solid var(--lesson-line); }
.lesson-modes a { display: flex; align-items: center; gap: 20px; min-height: 44px; padding: 10px 20px; border-radius: 8px; background: #f5f7fa; font-size: 12px; font-weight: 700; }
.lesson-modes a:nth-child(2) { background: var(--lesson-blue); color: white; }
.lesson-studio .lesson-layout { display: grid; grid-template-columns: minmax(0, 1fr); gap: 0; align-items: start; }
.lesson-reading, .lesson-sidebar { min-width: 0; }
.lesson-studio .lesson-document { max-width: none; margin: 0; font: 400 19px/1.8 Georgia, "Times New Roman", serif; }
.lesson-studio .lesson-document p { color: var(--lesson-ink); margin-block: 16px; line-height: inherit; }
.lesson-studio .lesson-document h2 { margin: 0 0 18px; padding: 0; border: 0; font: 800 24px/1.3 "Manrope", system-ui, sans-serif; letter-spacing: -.035em; text-wrap: pretty; }
.lesson-studio .lesson-document section + section { padding-top: 32px; margin-top: 32px; border-top: 1px solid var(--lesson-line); }
.lesson-studio .lesson-document h3 { margin: 24px 0 12px; font: 700 18px/1.4 "Manrope", system-ui, sans-serif; }
.lesson-studio .lesson-document :is(aside, blockquote) { margin: 28px 0; padding: 24px; border-radius: 12px; background: var(--lesson-mist); }
.lesson-studio .lesson-document :is(aside, blockquote) p:last-child { margin-bottom: 0; }
.lesson-studio .lesson-document a { color: var(--lesson-blue); text-decoration: underline; text-underline-offset: 3px; }
.lesson-studio .lesson-document :is(figcaption, caption, footer) { font: 500 12px/1.7 "Manrope", system-ui, sans-serif; color: var(--lesson-muted); }
.lesson-studio .lesson-document :is(table, pre) { font-size: 15px; }
.lesson-studio .lesson-document details { border: 1px solid var(--lesson-line); background: #f5f7fa; }
.lesson-studio .lesson-document details > summary { font: 700 14px/1.6 "Manrope", system-ui, sans-serif; }
.lesson-studio .lesson-practice { margin-top: 56px; padding-top: 0; border: 0; }
.lesson-practice-heading { padding: 28px 32px; background: var(--lesson-blue); color: white; border-radius: 16px 16px 0 0; }
.lesson-studio .lesson-label { font-size: 12px; font-weight: 700; color: inherit; }
.lesson-studio .lesson-practice-heading h2 { font: 400 34px/1.2 Georgia, "Times New Roman", serif; color: white; margin: 8px 0 12px; letter-spacing: -.035em; }
.lesson-studio .lesson-practice-heading p { color: white; font-size: 14px; line-height: 1.7; }
.lesson-practice-heading > span { display: block; margin-top: 16px; color: #d8eaff; font-size: 11px; }
.practice-task { border: 1px solid var(--lesson-line); border-top: 0; background: white; }
.practice-task > summary { display: flex; align-items: baseline; gap: 18px; padding: 24px; cursor: pointer; list-style: none; }
.practice-task > summary::-webkit-details-marker { display: none; }
.practice-task > summary::after { content: "+"; flex-shrink: 0; margin-left: auto; font-size: 22px; color: var(--lesson-blue); }
.practice-task[open] > summary::after { content: "−"; }
.practice-number { flex: 0 0 24px; white-space: nowrap; font-size: 12px; color: var(--lesson-blue); font-variant-numeric: tabular-nums; font-weight: 800; }
.lesson-studio .lesson-practice .practice-task { margin: 0; }
.lesson-studio .practice-task h3 { font-size: 15px; line-height: 1.65; letter-spacing: -.015em; text-wrap: pretty; }
.practice-task summary small { display: block; font-size: 11px; color: var(--lesson-muted); margin-top: 6px; }
.practice-task-body { padding: 0 24px 24px 58px; }
.lesson-studio .practice-task-body form { margin: 0; gap: 10px; }
.practice-task-body label { font-size: 12px; font-weight: 700; }
.lesson-studio .practice-task-body textarea { min-width: 0; padding: 16px; border: 1px solid var(--lesson-line); border-radius: 8px; background: #f8fafc; resize: vertical; font-size: 14px; line-height: 1.7; }
.practice-submit { display: flex; align-items: center; flex-wrap: wrap; gap: 14px; margin: 4px 0 18px; }
.lesson-studio .practice-submit .button { width: auto; min-height: 44px; padding: 10px 20px; border-radius: 8px; border-color: var(--lesson-blue); background: var(--lesson-blue); color: white; font-size: 12px; }
.practice-submit small { font-size: 11px; color: var(--lesson-muted); }
.lesson-studio .practice-task-body .link-button { width: fit-content; min-height: 44px; padding-block: 10px; color: var(--lesson-blue); font-size: 12px; text-decoration: underline; text-underline-offset: 4px; }
.practice-explanation { margin-block: 18px; padding: 20px; background: var(--lesson-mist); border-radius: 8px; font-size: 13px; }
.lesson-studio .practice-explanation p { margin-block: 8px; color: var(--lesson-ink); line-height: 1.8; }
.practice-explanation small { color: var(--lesson-muted); font-size: 11px; }
.lesson-studio .lesson-practice .practice-feedback { background: #f5f7fa; margin-top: 20px; padding: 20px; border: 0; border-radius: 8px; font-size: 13px; }
.lesson-studio .practice-feedback p { margin-bottom: 12px; color: var(--lesson-ink); line-height: 1.8; }
.practice-feedback small { font-size: 11px; color: var(--lesson-muted); }
.practice-history { margin-top: 24px; }
.practice-history > summary { cursor: pointer; font-size: 12px; }
.lesson-completion { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 20px; padding: 24px; background: #f5f7fa; border-radius: 0 0 16px 16px; }
.lesson-completion > div { flex: 1 1 240px; }
.lesson-completion strong { font-size: 14px; }
.lesson-studio .lesson-completion p { margin-top: 6px; font-size: 11px; color: var(--lesson-muted); }
.lesson-studio .lesson-completion form { margin: 0; }
.lesson-studio .lesson-completion .button { padding: 12px 16px; font-size: 11px; border-radius: 8px; background: white; color: var(--lesson-ink); }
.lesson-completed { padding: 8px 12px; border-radius: 8px; background: #c8f133; font-size: 12px; }
.lesson-reference { margin-top: 48px; padding-top: 32px; border-top: 1px solid var(--lesson-line); }
.lesson-section-heading { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 16px; }
.lesson-section-heading .lesson-label { margin-bottom: 8px; color: var(--lesson-blue); }
.lesson-studio .lesson-section-heading h2 { font: 400 30px/1.3 Georgia, "Times New Roman", serif; letter-spacing: -.03em; }
.lesson-section-heading a { flex-shrink: 0; padding-block: 10px; color: var(--lesson-blue); font-size: 12px; text-decoration: underline; }
.lesson-studio .lesson-reference > p { font-size: 13px; color: var(--lesson-muted); }
.lesson-reference > details { margin-top: 20px; padding: 20px 24px; border: 1px solid var(--lesson-line); border-radius: 12px; }
.lesson-reference > details > summary { cursor: pointer; font-size: 13px; font-weight: 700; }
.lesson-reference .study-notes { margin-top: 24px; font-size: 14px; }
.lesson-reference .study-notes h2 { font-size: 19px; }
.lesson-waiting { padding-block: 24px 64px; max-width: 70ch; }
.lesson-waiting img { margin-bottom: 24px; }
.lesson-studio .lesson-waiting h1 { font: 400 42px/1.2 Georgia, "Times New Roman", serif; }
.lesson-waiting p { margin-top: 20px; }
@media (max-width: 1100px) {
  .lesson-studio { padding: 28px; }
  .lesson-studio .lesson-layout { grid-template-columns: minmax(0, 1fr); gap: 0; }
  /* A narrower column needs the masthead to give up height, not the mode links. Tighten the
     spacing between blocks so the first concept starts sooner; the three links keep their size. */
  .lesson-context { margin-bottom: 16px; }
  .lesson-outcome { margin: 18px 0 22px; }
  .lesson-modes { padding-bottom: 20px; margin-bottom: 26px; }
}
@media (max-width: 850px) {
  .lesson-studio .lesson-layout { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 600px) {
  .lesson-studio { padding: 20px; border-radius: 16px; }
  .lesson-studio .lesson-toolbar { margin-bottom: 28px; gap: 6px; }
  .lesson-tools { gap: 16px; }
  .lesson-context { gap: 8px 12px; margin-bottom: 20px; font-size: 11px; }
  .lesson-context > span + span { padding-left: 12px; }
  .lesson-studio .lesson-masthead h1 { font-size: 38px; }
  .lesson-outcome { display: block; margin-block: 24px; }
  .lesson-outcome p { margin-top: 8px; }
  .lesson-modes { gap: 6px; padding-bottom: 24px; margin-bottom: 28px; }
  .lesson-modes a { padding: 10px 12px; gap: 10px; font-size: 11px; }
  .lesson-studio .lesson-document { font-size: 18px; }
  .lesson-studio .lesson-document h2 { font-size: 21px; }
  .lesson-practice-heading { padding: 24px; }
  .lesson-studio .lesson-practice-heading h2 { font-size: 30px; }
  .practice-task > summary { padding: 20px; gap: 12px; }
  .practice-task-body { padding: 0 20px 20px; }
  .lesson-section-heading { align-items: start; }
  .lesson-studio .lesson-section-heading h2 { font-size: 26px; }
}
@media print {
  .lesson-studio { width: 100%; max-width: none; padding: 0; color: black; background: white; font-size: 10pt; border-radius: 0; }
  .lesson-studio :is(.lesson-toolbar, .lesson-share-dialog, .lesson-modes, .lesson-sidebar, .lesson-outcome > span, .practice-task, .lesson-completion, .lesson-section-heading > a, .lesson-reference > p) { display: none !important; }
  .lesson-studio .lesson-layout { display: block; }
  .lesson-studio .lesson-masthead h1 { font-size: 28pt; max-width: none; }
  .lesson-context { margin-bottom: 12px; }
  .lesson-outcome { margin-block: 12px 24px; }
  .lesson-studio .lesson-document { font-size: 11pt; }
  .lesson-studio .lesson-document h2 { font-size: 15pt; break-after: avoid; }
  .lesson-studio .lesson-document section + section { margin-top: 20px; padding-top: 20px; }
  .lesson-studio .lesson-practice { display: none; }
  .lesson-studio .lesson-print-answers { display: block; break-before: page; }
  .lesson-reference { margin-top: 24px; }
  .lesson-reference > details { border: 0; padding: 0; }
  .lesson-reference > details > summary { display: none; }
  .lesson-studio details::details-content { content-visibility: visible; }
  .lesson-studio details > * { display: block !important; }
  .lesson-studio details > summary { display: none !important; }
}
.lesson-standalone .lesson-reading { max-width: 72ch; }
.lesson-studio .lesson-toolbar { display: flex; flex-wrap: wrap; align-items: center; }
.lesson-studio .lesson-toolbar button { border: 0; padding: 0; color: inherit; background: transparent; cursor: pointer; }
.lesson-studio .lesson-print-answers { display: none; }
.lesson-studio .lesson-document :is(ul, ol) { padding-left: 24px; }
.lesson-studio .lesson-document li { margin-top: 8px; }
.lesson-studio .lesson-document table { display: block; max-width: 100%; overflow-x: auto; border-collapse: collapse; margin-block: 24px; }
.lesson-studio .lesson-document :is(th, td) { border: 1px solid var(--lesson-line); padding: 12px; text-align: left; }
.lesson-studio .lesson-document th { background: var(--lesson-mist); }
.lesson-studio .lesson-document pre { overflow-x: auto; padding: 20px; border-radius: 8px; background: #f5f7fa; }
.lesson-studio .lesson-document details { margin-block: 24px; padding: 20px; border-radius: 12px; }
.lesson-studio .lesson-document details > summary { cursor: pointer; min-height: 44px; align-content: center; }
.lesson-studio .lesson-document strong { font-weight: 700; }
.lesson-studio .lesson-document footer { margin-top: 32px; padding-top: 20px; border-top: 1px solid var(--lesson-line); }
.lesson-studio .practice-task-body > textarea { width: 100%; margin: 8px 0 16px; }
.lesson-studio .practice-explanation > summary { cursor: pointer; min-height: 44px; align-content: center; font-size: 12px; }
.lesson-export-footer { margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--lesson-line); color: var(--lesson-muted); font-size: 12px; }
.lesson-export-footer a { color: var(--lesson-blue); text-decoration: underline; }
@media print {
  .lesson-studio .lesson-print-answers { display: block; }
  .lesson-studio .lesson-document table { display: table; overflow: visible; }
  .lesson-studio :is(table, pre, figure, .practice-explanation) { break-inside: avoid; }
  .lesson-studio .lesson-reference .study-notes { display: block !important; }
  .lesson-studio .lesson-reference details::details-content { content-visibility: visible; }
}

/* Keep the explanation readable and give each teaching step a quiet visual marker. */
.lesson-studio .lesson-reading { max-width: 76ch; margin-inline: auto; width: 100%; }
.lesson-studio #explanation > article { counter-reset: lesson-step; }
.lesson-studio #explanation > article > section { counter-increment: lesson-step; }
.lesson-studio #explanation > article > section > h2::before { content: counter(lesson-step, decimal-leading-zero); display: block; margin-bottom: 10px; color: var(--lesson-blue); font: 700 11px/1.5 "Manrope", system-ui, sans-serif; letter-spacing: .06em; }
.lesson-studio .lesson-document :is(ol, ul) { display: grid; gap: 10px; margin-block: 20px; }
.lesson-studio .lesson-document figure { margin: 28px 0; }
.lesson-studio .lesson-document figcaption { margin-top: 10px; }

.reference-studio { max-width: 880px; }
.reference-actions { display: flex; flex-wrap: wrap; gap: 20px; align-items: center; }
.reference-studio .lesson-masthead { margin-bottom: 28px; padding-bottom: 24px; border-bottom: 2px solid var(--lesson-ink); }
.reference-studio .lesson-masthead h1 { font-size: 36px; }
.reference-studio .reference-note { margin-top: 12px; color: var(--lesson-muted); font-size: 12px; }
.reference-studio .lesson-document { font: 500 14px/1.65 "Manrope", system-ui, sans-serif; }
.reference-studio .lesson-document h2 { font-size: 19px; }
@media print {
  @page { margin: 15mm; }
  .reference-studio .reference-note { display: none; }
  .reference-studio .lesson-masthead h1 { font-size: 21pt; }
  .reference-studio .lesson-document { font-size: 9.5pt; }
  .reference-studio .lesson-document h2 { font-size: 12pt; }
  .reference-studio .lesson-document :is(section, aside, table, pre) { break-inside: avoid; }
  .reference-studio .lesson-document section + section { padding-top: 12px; margin-top: 12px; }
  .reference-studio .lesson-document p { margin-block: 8px; }
}

.practice-follow-up { padding: 16px; margin-bottom: 20px !important; border-left: 3px solid var(--lesson-blue); background: var(--lesson-mist); font-size: 14px; line-height: 1.7; }
.practice-follow-up strong { display: block; margin-bottom: 6px; }