.learning-page { max-width: 1180px; margin: 0 auto; padding: 56px 32px 88px; }
.learning-head { max-width: 800px; margin-bottom: 48px; }
.learning-head h1 { font-family: "Newsreader", Georgia, serif; font-size: clamp(2.4rem, 5vw, 4.2rem); line-height: 1.08; letter-spacing: -.04em; margin: 12px 0 22px; }
.learning-lead { max-width: 690px; color: var(--muted); font-size: 1.08rem; }
.learning-page h2 { font-family: "Newsreader", Georgia, serif; font-size: clamp(1.6rem, 3vw, 2.2rem); line-height: 1.2; letter-spacing: -.02em; }
.learning-page h3 { line-height: 1.4; }
.learning-page a:focus-visible, .learning-page button:focus-visible, .learning-page input:focus-visible, .learning-page select:focus-visible, .learning-page textarea:focus-visible, .learning-page summary:focus-visible, .prerequisite-check summary:focus-visible { outline: 3px solid var(--blue); outline-offset: 4px; }
.learning-page .btn { min-height: 44px; white-space: normal; }
.learning-page input:not([type="checkbox"]):not([type="radio"]):not([type="range"]), .learning-page select, .learning-page textarea { width: 100%; max-width: 100%; min-height: 46px; background: #fff; color: var(--ink); border: 1px solid var(--line); border-radius: 8px; padding: 10px 12px; font: inherit; }
.learning-page label { font-size: .87rem; font-weight: 650; }
.learning-page label > input, .learning-page label > select, .learning-page label > textarea { margin-top: 7px; }
.learning-list { border-top: 1px solid var(--line); }
.learning-row { border-bottom: 1px solid var(--line); }
.method-choice { display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 32px; align-items: center; padding: 28px 8px; text-decoration: none; transition: background .18s ease; }
.method-choice:hover { background: var(--paper-2); }
.method-choice-end { display: flex; align-items: center; gap: 26px; white-space: nowrap; font-size: .82rem; color: var(--muted); }
.method-choice-arrow { font-size: 1.4rem; color: var(--coral-dark); transition: transform .18s ease; }
.method-choice:hover .method-choice-arrow { transform: translateX(4px); }
.learning-row h2 { margin: 5px 0 12px; }
.exercise-result h2 a, .revision-course h3 a { text-decoration: none; }
.method-choice:hover h2, .exercise-result h2 a:hover, .revision-course h3 a:hover { text-decoration: underline; text-underline-offset: 5px; text-decoration-thickness: 1px; }
.learning-row p { margin: 0; max-width: 680px; }
.learning-meta { font-size: .76rem; color: var(--muted); line-height: 1.5; }
.learning-breadcrumb { margin-bottom: 28px; font-size: .82rem; color: var(--muted); }
.method-layout { display: grid; grid-template-columns: minmax(0, 1fr) 220px; gap: 70px; align-items: start; }
.method-article { min-width: 0; width: 100%; max-width: 100%; }
.method-article > section, .method-warning { margin: 0 0 48px; }
.method-steps { list-style: none; counter-reset: method-step; padding: 0; }
.method-steps > li { counter-increment: method-step; position: relative; padding: 6px 0 20px 48px; }
.method-steps > li::before { content: counter(method-step, decimal-leading-zero); position: absolute; left: 0; top: 9px; color: var(--coral-dark); font-weight: 800; font-size: .82rem; }
.method-steps h3 { margin: 0 0 8px; font-size: 1rem; }
.method-steps p { margin: 0; }
.calculation-guide { padding: 0; list-style: none; }
.calculation-guide > li { border-left: 2px solid var(--line); padding: 2px 0 2px 22px; margin: 22px 0; }
.calculation-guide > li > p { margin: 0 0 7px; color: var(--muted); font-size: .85rem; }
.calculation-guide .math-block { margin: 8px 0; }
.method-warning { background: var(--paper-2); border-left: 3px solid var(--amber); padding: 20px 24px; }
.method-warning h2 { font-family: "Manrope", sans-serif; font-size: 1rem; margin-top: 0; }
.method-aside { position: sticky; top: 100px; display: grid; gap: 16px; border-left: 1px solid var(--line); padding-left: 24px; font-size: .85rem; }
.method-aside .eyebrow { margin: 0; }
.learning-disclosure { border-top: 1px solid var(--line); margin: 16px 0; padding: 16px 0; }
.learning-disclosure summary, .prerequisite-check summary { cursor: pointer; font-weight: 750; min-height: 28px; }
.learning-disclosure[open] > :not(summary), .prerequisite-check[open] form { animation: learning-appear .18s ease-out; }
.learning-disclosure summary:hover { color: var(--coral-dark); }
.practice-verdict { padding-top: 10px; }
.practice-verdict .btn { margin: 4px 4px 4px 0; }
.learning-status { min-height: 1.5em; color: var(--muted); font-size: .87rem; }
.variation-summary, .lab-value-table { max-width: 100%; overflow-x: auto; }
.learning-page table { border-collapse: collapse; width: 100%; font-size: .86rem; }
.learning-page th, .learning-page td { padding: 12px; text-align: left; border-bottom: 1px solid var(--line); }
.learning-page caption { text-align: left; color: var(--muted); margin-bottom: 12px; font-size: .82rem; }
.prerequisite-part { margin-bottom: 28px; }
.is-prerequisite-gated .reader-actions, .is-prerequisite-gated .reader-modes, .is-prerequisite-gated .reader-head .encouragement-note, .is-prerequisite-gated .reading-progress { display: none; }
.prerequisite-entry { width: min(1120px, calc(100% - 64px)); margin: 0 auto 70px; padding: 36px 0; border-top: 1px solid var(--line); display: grid; grid-template-columns: minmax(0,.9fr) minmax(0,1.1fr); gap: 64px; align-items: start; }
.prerequisite-intro h2 { font-family: "Newsreader", Georgia, serif; font-size: 2rem; line-height: 1.15; margin: 0 0 18px; }
.prerequisite-intro > p:not(.eyebrow) { font-size: .92rem; color: var(--muted); }
.prerequisite-intro .eyebrow { font-size: .7rem; }
.prerequisite-advice { border-left: 2px solid var(--coral); padding-left: 16px; }
.prerequisite-skip { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; margin-top: 28px; }
.prerequisite-pass { border: 0; padding: 10px 0; background: transparent; text-decoration: underline; text-underline-offset: 4px; cursor: pointer; font-size: .8rem; color: var(--muted); }
.prerequisite-entry .prerequisite-check { border: 0; padding: 0; }
.prerequisite-entry .prerequisite-check form { padding: 0; }
.prerequisite-step-label { margin: 0 0 22px; font-size: .82rem; font-weight: 750; color: var(--coral-dark); }
.prerequisite-entry .check-options { gap: 10px; margin-top: 18px; }
.prerequisite-entry .check-options label { min-height: 46px; padding: 12px 16px; border: 1px solid var(--line); background: var(--white); }
.prerequisite-entry .check-options label:has(input:checked) { border-color: var(--coral-dark); background: #fff4f0; }
.prerequisite-entry fieldset { padding-bottom: 20px; margin-bottom: 0; border-bottom: 0; }
.prerequisite-step-actions { display: flex; gap: 12px; }
.prerequisite-validation { color: var(--coral-dark); font-size: .86rem; }
.prerequisite-validation:empty { display: none; }
.prerequisite-completion { border-top: 1px solid var(--line); margin-top: 24px; padding-top: 18px; font-size: .9rem; }
.prerequisite-entry button:focus-visible, .prerequisite-entry input:focus-visible { outline: 3px solid var(--blue); outline-offset: 4px; }
.prerequisite-check { border-block: 1px solid var(--line); padding: 18px 0; }
.prerequisite-check summary small { font-size: .75rem; font-weight: 500; color: var(--muted); margin-left: 12px; }
.prerequisite-check form { padding-top: 14px; }
.prerequisite-check fieldset { min-width: 0; border: 0; border-bottom: 1px solid var(--line); padding: 16px 0 24px; margin: 0 0 22px; }
.prerequisite-check legend { font-weight: 650; padding: 0; font-size: .92rem; }
.check-options { display: grid; gap: 4px; }
.check-options label { display: flex; gap: 12px; align-items: baseline; padding: 9px; cursor: pointer; border-radius: 5px; font-size: .87rem; }
.check-options label:hover { background: var(--paper-2); }
.check-options input { flex-shrink: 0; accent-color: var(--navy); }
.check-feedback { font-size: .85rem; padding-left: 12px; border-left: 3px solid var(--coral-dark); }
[data-result="correct"] .check-feedback { border-color: #167666; }
.course-learning-links { border-top: 1px solid var(--line); margin: 45px 0 0; padding: 24px 0; display: flex; flex-wrap: wrap; gap: 12px 24px; font-size: .84rem; }
.learning-footer { display: flex; gap: 15px 24px; flex-wrap: wrap; margin: 18px 0 26px; font-size: .84rem; }
.learning-footer a { text-decoration: none; opacity: .82; }
.learning-footer a:hover { opacity: 1; text-decoration: underline; }
.exercise-filters { background: var(--paper-2); padding: 24px; display: grid; grid-template-columns: minmax(0,1fr) auto; gap: 20px; margin-bottom: 28px; }
.filter-primary { display: grid; grid-template-columns: 1fr .8fr 1.4fr; gap: 18px; grid-column: 1 / -1; }
.filter-more { grid-column: 1 / -1; grid-row: 2; }
.filter-more summary { cursor: pointer; width: fit-content; padding: 8px 0; font-size: .85rem; font-weight: 650; }
.filter-secondary { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 18px; margin-top: 18px; }
.filter-reset { align-self: start; justify-self: end; grid-column: 2; grid-row: 2; background: transparent; padding: 8px 0; border: 0; text-decoration: underline; text-underline-offset: 4px; cursor: pointer; font-size: .83rem; color: var(--muted); }
.exercise-result { display: flex; justify-content: space-between; align-items: start; gap: 25px; border-bottom: 1px solid var(--line); padding: 24px 0; }
.exercise-result h2 { font-family: "Manrope", sans-serif; font-size: 1.02rem; margin: 6px 0 0; letter-spacing: 0; line-height: 1.55; }
.exercise-result .learning-meta { margin: 0; }
.exercise-estimate { min-width: 130px; font-size: .8rem; margin: 0; color: var(--muted); text-align: right; }
.exercise-estimate span { display: block; }
[data-exercise-more] { margin-top: 24px; }
.local-data-note { max-width: 790px; padding-left: 18px; border-left: 2px solid var(--line); color: var(--muted); font-size: .88rem; }
.revision-resume { border-block: 1px solid var(--line); padding: 28px 0; margin: 32px 0 46px; }
.revision-resume h2 { margin: 8px 0; }
.revision-session { display: grid; grid-template-columns: 1fr auto; gap: 24px; margin-bottom: 48px; }
.revision-session h2 { margin: 8px 0; }
.revision-session form { display: flex; gap: 14px; align-items: end; }
[data-session-plan] { grid-column: 1 / -1; }
.session-plan { padding: 0; list-style: none; }
.session-plan li { display: flex; gap: 24px; border-top: 1px solid var(--line); padding: 20px 0; }
.session-plan li > span { color: var(--coral-dark); min-width: 65px; font-weight: 750; }
.session-plan p { margin: 6px 0; font-size: .87rem; color: var(--muted); }
.revision-review-list { padding: 0; list-style: none; }
.revision-review-list li { padding: 18px 0; border-bottom: 1px solid var(--line); display: flex; justify-content: space-between; gap: 24px; }
.revision-review-list span { color: var(--muted); font-size: .83rem; }
.revision-course { display: flex; justify-content: space-between; align-items: center; gap: 24px; padding: 20px 0; border-bottom: 1px solid var(--line); }
.revision-course h3 { margin: 4px 0; font-size: 1rem; }
.revision-course p { margin: 0; font-size: .82rem; color: var(--muted); }
.revision-course > a { font-size: .85rem; white-space: nowrap; }
.backup-settings { margin-top: 48px; }
.backup-settings > details { margin-top: 30px; }
.backup-settings [data-clear-progress] { display: block; margin-top: 14px; }
.backup-actions { display: flex; flex-wrap: wrap; gap: 20px; align-items: center; margin-top: 20px; }
.file-picker input { display: block; }
.about-content { max-width: 760px; }
.about-content section { margin-bottom: 42px; }
.report-form { max-width: 730px; display: grid; gap: 22px; }
.report-form p { font-size: .84rem; color: var(--muted); }
.report-form button { justify-self: start; }
.math-lab { padding: 38px 0 48px; border-top: 1px solid var(--line); scroll-margin-top: 90px; }
.lab-heading { max-width: 700px; }
.lab-heading h2 { margin: 6px 0 14px; }
.lab-layout { display: grid; grid-template-columns: minmax(0,1.6fr) minmax(245px,1fr); gap: 34px; align-items: start; margin-top: 28px; }
.lab-plot { display: block; width: 100%; height: auto; background: #fff; border: 1px solid var(--line); border-radius: 10px; }
.lab-plot text { font-family: "Manrope", sans-serif; font-size: 12px; fill: var(--ink); }
.plot-grid { stroke: #ece9e2; stroke-width: 1; }
.plot-axis { stroke: #a8a7a3; stroke-width: 1.2; }
.plot-function { stroke: #3f61c7; stroke-width: 3; fill: none; }
.plot-tangent { stroke: var(--coral-dark); stroke-width: 3; fill: none; }
.plot-secant { stroke: var(--navy); stroke-width: 2; fill: none; stroke-dasharray: 8 6; }
.plot-point { fill: var(--navy); stroke: #fff; stroke-width: 1.5; }
.plot-stem { stroke: #b3bee0; stroke-width: 2; }
.plot-legend { display: flex; flex-wrap: wrap; gap: 8px 18px; font-size: .75rem; color: var(--muted); }
.lab-controls { display: grid; gap: 22px; }
.lab-controls label { display: block; }
.lab-controls output { float: right; font-weight: 800; font-variant-numeric: tabular-nums; }
.lab-controls input[type="range"] { width: 100%; accent-color: var(--coral-dark); min-height: 28px; }
.lab-readout { border-left: 2px solid var(--line); padding-left: 18px; font-size: .87rem; }
.lab-readout p:first-child { margin-top: 0; }
.lab-readout p:last-child { margin-bottom: 0; }
.lab-controls .btn { justify-self: start; }
.lab-controls > a { font-size: .83rem; }
.header-inner { gap: 20px; }
.desktop-nav { gap: 1.05rem; }
.desktop-nav a { display: inline-flex; align-items: center; min-height: 44px; white-space: nowrap; }
.desktop-nav a[aria-current="page"] { text-decoration: underline; text-underline-offset: 7px; text-decoration-color: var(--coral-dark); text-decoration-thickness: 2px; }
.header-support { display: inline-flex; align-items: center; min-height: 44px; padding-left: 20px; border-left: 1px solid var(--line); font-size: .84rem; font-weight: 650; text-decoration: none; white-space: nowrap; opacity: .75; }
.header-support:hover, .header-support[aria-current="page"] { opacity: 1; text-decoration: underline; text-underline-offset: 5px; }
.home .header-support { border-color: rgba(255,255,255,.24); }
.header-support:focus-visible { outline: 3px solid var(--coral); outline-offset: 4px; }
@keyframes learning-appear { from { opacity: .4; transform: translateY(-3px); } to { opacity: 1; transform: none; } }
@media (max-width: 1190px) and (min-width: 861px) { .header-search .search-label, .header-search .kbd { display: none; } .header-inner { gap: 16px; } .desktop-nav { gap: .85rem; } .desktop-nav a, .header-support { font-size: .8rem; } .header-support { padding-left: 16px; } }
@media (max-width: 860px) {
  .learning-page { padding: 32px 22px 64px; }
  .learning-head { margin-bottom: 32px; }
  .prerequisite-entry { width: calc(100% - 40px); grid-template-columns: 1fr; gap: 30px; padding-top: 26px; }
  .is-prerequisite-gated .reader-head-inner { padding-block: 24px; }
  .is-prerequisite-gated .reader-title > p { display: none; }
  .header-support { display: none; }
  .header-inner { gap: .65rem; }
  .mobile-nav a[aria-current="page"] { color: var(--coral-dark); font-weight: 750; }
  .mobile-nav .mobile-support { margin-top: 12px; border-bottom: 0; color: var(--muted); }
  .method-layout, .lab-layout { grid-template-columns: 1fr; gap: 28px; }
  .method-aside { position: static; padding: 22px 0 0; border-left: 0; border-top: 1px solid var(--line); }
  .exercise-filters { padding: 20px; }
  .filter-primary { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .filter-primary > label:last-child { grid-column: 1 / -1; }
  .filter-secondary { grid-template-columns: 1fr; }
  .revision-session { grid-template-columns: 1fr; }
  .revision-session form { justify-content: start; }
  .learning-footer { gap: 12px 20px; }
}
@media (max-width: 540px) {
  .learning-page { padding-inline: 18px; }
  .method-choice { grid-template-columns: minmax(0,1fr); gap: 12px; padding: 22px 0; }
  .method-choice-end { justify-content: space-between; }
  .prerequisite-entry { width: calc(100% - 36px); }
  .prerequisite-intro h2 { font-size: 1.7rem; }
  .prerequisite-skip { margin-top: 20px; }
  .exercise-filters { padding: 18px; }
  .filter-primary { grid-template-columns: 1fr; }
  .exercise-result, .revision-course, .revision-review-list li { flex-direction: column; gap: 10px; }
  .exercise-estimate { text-align: left; }
  .exercise-estimate span { display: inline; margin-left: 14px; }
  .revision-session form { align-items: stretch; flex-direction: column; }
  .backup-actions { align-items: stretch; flex-direction: column; }
  .prerequisite-check summary small { display: block; margin: 5px 0 0 18px; }
  .method-steps > li { padding-left: 36px; }
  .calculation-guide > li { padding-left: 14px; }
  .course-learning-links { flex-direction: column; }
}
@media (max-width: 380px) { .filter-reset { grid-column: 1 / -1; grid-row: 3; justify-self: start; } }
.explore-disclosure > .math-lab { border: 0; margin: 0; padding: 22px 0 0; }
.explore-disclosure { scroll-margin-top: 100px; }
.exploration .lab-layout { margin-top: 18px; gap: 24px; }
.exploration .lab-controls[hidden] { display: none; }
.exploration:not([data-explore-ready]) .lab-layout { display: none; }
.explore-question { max-width: 72ch; }
.explore-actions { display: flex; gap: 10px; flex-wrap: wrap; }
.explore-readout { margin: 18px 0; }
.explore-takeaway { border-left: 3px solid var(--accent, #5267dc); padding-left: 15px; margin-top: 22px; }
.explore-index { display: flex; flex-wrap: wrap; gap: 10px 24px; margin: 22px 0 36px; }
.explore-index a { text-underline-offset: 4px; }
.explore-interval { stroke: #3f61c7; stroke-width: 7; stroke-linecap: round; }
.explore-coral-point, .explore-square { fill: #b94f37; stroke: #fff; stroke-width: 1.5; }
.explore-root { fill: #fff; stroke: #3f61c7; stroke-width: 2.5; }
.explore-cube-edge { stroke: #727b89; stroke-width: 1.5; fill: none; }
.explore-band { fill: #3f61c7; opacity: .08; }
.explore-threshold { stroke: #727b89; stroke-width: 1.5; stroke-dasharray: 2 5; }
.explore-plot text { font-size: 15px; }
@media (max-width: 750px) { .exploration .lab-layout { grid-template-columns: minmax(0, 1fr); } .explore-disclosure > .math-lab { padding-inline: 0; } }
@media (max-width: 540px) { .explore-plot text { font-size: 23px; } }
@media (prefers-reduced-motion: reduce) { .learning-disclosure[open] > :not(summary), .prerequisite-check[open] form { animation: none; } .training-nav a, .training-nav a::after, .method-choice, .method-choice-arrow { transition: none; } .method-choice:hover .method-choice-arrow { transform: none; } }
@media print { .method-aside, .practice-verdict, .lab-controls input, .learning-footer, .backup-settings { display: none !important; } .method-layout { display: block; } }
.explore-population { fill: #edf0f7; stroke: #647083; stroke-width: 2; }
.explore-trace-active { fill: #e1e5fb; stroke: #5966b6; stroke-width: 2; }
.explore-population-b { fill: #5966b6; }
.explore-positive-area { fill: #dfe5f5; stroke: #536cb5; stroke-width: 1; }
.explore-negative-area { fill: #f2d8d0; stroke: #ad523c; stroke-width: 1; }
.explore-binomial-selected { fill: #3f61c7; stroke: #293f84; stroke-width: .6; }
.explore-binomial-other { fill: #ccd0db; stroke: #747b91; stroke-width: .6; }
[data-explore="statistics"] .plot-secant { stroke: #3f61c7; }
[data-explore="statistics"] .plot-point, [data-explore="concentration"] .plot-point { fill: #3f61c7; }

.method-section, .method-anchor, .method-practice { scroll-margin-top: 100px; }
.method-layout { grid-template-columns: minmax(0, 1fr) 235px; gap: 50px; }
.method-article { min-width: 0; }
.method-article p, .method-article li { line-height: 1.85; }
.method-article h2 { line-height: 1.3; }
.method-article h4 { margin-top: 25px; font-size: 1.05rem; }
.method-example { border-left: 3px solid var(--coral); padding: 0 0 0 23px; margin: 32px 0; }
.method-example > h3 { margin-top: 0; }
.method-practice { margin: 38px 0; padding: 25px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.practice-invitation { color: var(--muted); font-size: .9em; }
.method-aside { max-height: calc(100vh - 120px); overflow-y: auto; padding-right: 8px; }
.method-aside nav { margin-bottom: 30px; }
.method-aside a { display: block; line-height: 1.5; margin-bottom: 12px; }
.method-mobile-contents { display: none; }
.method-checklist dt { font-weight: 700; margin-top: 22px; }
.method-checklist dd { margin-left: 0; }
.method-article .lab-layout { grid-template-columns: minmax(0, 1fr); }
.method-article .lab-controls { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px 24px; }
.method-article .lab-controls[hidden] { display: none; }
.method-article .explore-actions { grid-column: 1 / -1; }
.legacy-exploration:not([data-lab-ready]) .lab-layout { display: none; }
.legacy-exploration[data-lab-ready] .lab-layout { display: grid; }
.induction-chain { display: flex; align-items: center; justify-content: space-between; gap: 14px; border-block: 1px solid var(--line); padding: 22px 0; margin: 28px 0; font-size: .88rem; }
.induction-chain strong { display: inline-block; color: var(--navy, #1c2035); margin-top: 8px; }
.method-domain { margin: 38px 0 18px; }
.method-choice h3 { font-family: "Newsreader", Georgia, serif; font-size: clamp(1.35rem, 2.4vw, 1.9rem); font-weight: 600; margin: 5px 0 12px; }
.method-choice:hover h3 { text-decoration: underline; text-underline-offset: 5px; text-decoration-thickness: 1px; }
.method-index-nav { display: flex; flex-wrap: wrap; gap: 12px 22px; border-block: 1px solid var(--line); padding-block: 16px; }

/* A focused workspace for one exercise, using the course typography. */
.learning-page:has(.exercise-player) { max-width: 1240px; padding-top: 30px; }
.exercise-topline { display: flex; justify-content: space-between; align-items: center; gap: 20px; margin-bottom: 32px; font-size: .85rem; }
.exercise-back { display: inline-flex; align-items: center; min-height: 44px; padding: 8px 12px; border: 1px solid var(--line); border-radius: 6px; text-decoration: none; background: white; font-weight: 750; }
.exercise-back:hover { border-color: var(--coral-dark); color: var(--coral-dark); }
.exercise-course-link { text-underline-offset: 4px; color: var(--muted); }
.exercise-player-head { max-width: 900px; margin-bottom: 32px; }
.exercise-player-head .learning-meta { font-size: .83rem; line-height: 1.6; margin-bottom: 12px; }
.exercise-player-head h1 { margin: 0; font-family: "Newsreader", Georgia, serif; font-size: clamp(2rem, 3.7vw, 3.2rem); line-height: 1.15; letter-spacing: -.025em; }
.exercise-workspace { display: grid; grid-template-columns: minmax(0, 1fr) 224px; gap: 56px; align-items: start; }
.exercise-article { min-width: 0; }
.exercise-article > section { margin: 0 0 44px; }
.exercise-article h2 { font-family: "Manrope", sans-serif; font-size: .8rem; font-weight: 800; color: var(--muted); letter-spacing: .08em; text-transform: uppercase; scroll-margin-top: 20px; }
.exercise-statement { border-top: 1px solid var(--line); padding-top: 20px; }
.exercise-statement > h2 { margin: 0 0 18px; }
.exercise-article ol, .exercise-article ul { padding-left: 1.5em; }
.exercise-article li { margin-block: .5em; }
.exercise-companion { position: sticky; top: calc(var(--header-height) + 24px); border-left: 1px solid var(--line); padding-left: 24px; }
.exercise-companion .eyebrow { font-size: .67rem; margin-top: 0; }
.exercise-timer span { display: block; font-size: .78rem; color: var(--muted); }
.exercise-timer output { display: block; font-size: 2rem; font-weight: 650; font-variant-numeric: tabular-nums; letter-spacing: -.03em; }
.exercise-time-goal { font-size: .8rem; margin: 10px 0; }
.exercise-pause { min-height: 44px; border: 1px solid var(--line); border-radius: 6px; background: white; padding: 8px 12px; cursor: pointer; font-size: .78rem; font-weight: 650; }
.exercise-pause:hover { border-color: var(--coral-dark); }
.exercise-timer-note { font-size: .76rem; line-height: 1.6; color: var(--muted); }
.exercise-companion nav { display: grid; gap: 8px; border-top: 1px solid var(--line); padding-top: 16px; margin-top: 22px; }
.exercise-companion nav a { padding-block: 6px; font-size: .8rem; text-underline-offset: 4px; }
.exercise-assistance > p { font-size: .88rem; color: var(--muted); }
.exercise-hint { border-block-start: 1px solid var(--line); }
.exercise-hint:last-child { border-block-end: 1px solid var(--line); }
.exercise-hint > summary { padding: 16px 4px; min-height: 52px; cursor: pointer; color: var(--ink); font-size: .9rem; font-weight: 750; }
.exercise-hint > summary:hover { color: var(--coral-dark); }
.exercise-hint > div { padding: 0 18px 14px; border-left: 2px solid var(--coral); font-size: .93rem; }
.exercise-hint > div p { margin-top: 0; }
.exercise-hint[open] > div { animation: learning-appear .18s ease-out; }
.exercise-correction { border-top: 1px solid var(--line); margin-top: 28px; padding-top: 12px; }
.exercise-correction[hidden] { display: none; }
.exercise-correction .lesson-callout { margin-top: 12px; }
.exercise-reflection-dialog { width: min(580px, calc(100% - 32px)); max-height: calc(100svh - 32px); overflow-y: auto; padding: clamp(24px, 4vw, 38px); border: 1px solid var(--line); border-radius: 12px; color: var(--ink); background: var(--paper); box-shadow: var(--shadow); }
.exercise-reflection-dialog::backdrop { background: rgba(16,26,45,.45); }
.exercise-reflection-dialog h2 { font-family: "Newsreader", Georgia, serif; font-size: 2rem; line-height: 1.15; margin: 0 0 20px; letter-spacing: -.02em; }
.exercise-reflection-dialog .eyebrow { margin-top: 0; }
.exercise-reflection-dialog > p:not(.eyebrow) { font-size: .95rem; }
.exercise-reminder-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.exercise-reminder-actions .btn { flex: 1; font-size: .8rem; }
.exercise-skip-reminder { flex-basis: 100%; min-height: 44px; padding: 10px 0 0; border: 0; background: none; text-decoration: underline; text-underline-offset: 4px; color: var(--muted); font-size: .82rem; cursor: pointer; }
.exercise-reflection-dialog button:focus-visible { outline: 3px solid var(--blue); outline-offset: 3px; }
.exercise-error h1 { font-family: "Newsreader", Georgia, serif; font-size: 2.2rem; }
@media (max-width: 960px) {
  .exercise-workspace { gap: 28px; grid-template-columns: minmax(0,1fr) 195px; }
  .exercise-companion { padding-left: 18px; }
}
@media (max-width: 720px) {
  .learning-page:has(.exercise-player) { padding-top: 18px; }
  .exercise-topline { margin-bottom: 24px; font-size: .75rem; gap: 12px; }
  .exercise-topline .exercise-course-link { text-align: right; }
  .exercise-workspace { display: flex; flex-direction: column; gap: 24px; }
  .exercise-article { width: 100%; }
  .exercise-companion { order: -1; position: static; width: 100%; display: grid; grid-template-columns: minmax(0,1fr) auto; align-items: center; gap: 4px 14px; border: 0; border-top: 1px solid var(--line); padding: 16px 0 0; }
  .exercise-companion .eyebrow, .exercise-companion nav { display: none; }
  .exercise-timer { display: flex; align-items: baseline; flex-wrap: wrap; gap: 8px; }
  .exercise-timer output { font-size: 1.3rem; }
  .exercise-pause { grid-column: 2; grid-row: 1; max-width: 155px; }
  .exercise-time-goal { grid-column: 1 / -1; margin: 4px 0; font-size: .73rem; color: var(--muted); }
  .exercise-timer-note { grid-column: 1 / -1; margin: 0; font-size: .73rem; }
  .exercise-player-head { margin-bottom: 22px; }
  .exercise-player-head h1 { font-size: 2rem; }
  .exercise-reflection-dialog h2 { font-size: 1.75rem; }
  .exercise-reminder-actions { flex-direction: column; }
  .exercise-reflection-dialog { max-height: calc(100svh - 24px); }
}
@media (prefers-reduced-motion: reduce) { .exercise-hint[open] > div { animation: none; } }
@media print { .exercise-topline, .exercise-companion, .exercise-assistance, [data-exercise-reveal] { display: none; } .exercise-workspace { display: block; } }

/* The resource menu stays available while reading or manipulating a graph. */
.learning-page:has(.training-workspace) { max-width: 1480px; padding-top: 38px; }
.training-workspace { display: grid; grid-template-columns: 250px minmax(0, 1fr); gap: clamp(32px, 4vw, 64px); align-items: start; }
.training-sidebar { position: sticky; top: calc(var(--header-height) + 24px); min-width: 0; }
.training-sidebar > summary { display: none; }
.training-menu-panel { display: flex; flex-direction: column; max-height: calc(100svh - var(--header-height) - 48px); }
.training-label { margin: 0 0 10px; color: var(--muted); font-size: .66rem; font-weight: 800; letter-spacing: .09em; text-transform: uppercase; }
.training-resource-label { padding-left: 12px; }
.training-nav { display: grid; gap: 6px; flex-shrink: 0; }
.training-nav a { display: grid; grid-template-columns: 22px 1fr 18px; align-items: center; gap: 11px; min-height: 48px; padding: 10px 12px; border: 1px solid var(--line); border-radius: 7px; background: var(--white); color: var(--ink); text-decoration: none; font-size: .9rem; font-weight: 750; transition: background .16s ease, border-color .16s ease; }
.training-nav a:hover { border-color: var(--coral-dark); background: #fff4f0; }
.training-nav a[aria-current="page"] { background: var(--navy); border-color: var(--navy); color: white; }
.training-icon { width: 22px; height: 22px; }
.training-link-arrow { justify-self: end; opacity: .65; font-size: 1.1rem; }
.training-local { min-height: 0; overflow-y: auto; overscroll-behavior: contain; scrollbar-width: thin; margin-top: 24px; padding: 22px 6px 6px 0; border-top: 1px solid var(--line); }
.training-local-nav { margin-bottom: 24px; }
.training-local-nav:last-child { margin-bottom: 0; }
.training-local-nav .training-label { padding-left: 12px; }
.training-local-nav a { display: flex; align-items: center; justify-content: space-between; gap: 6px; min-height: 44px; padding: 8px 12px; border-left: 2px solid transparent; color: #505a6c; text-decoration: none; font-size: .82rem; line-height: 1.4; transition: background .16s ease, color .16s ease; }
.training-local-nav a:hover { color: var(--ink); background: var(--paper-2); }
.training-local-nav a[aria-current="location"] { border-left-color: var(--coral-dark); color: var(--coral-dark); background: #f9eae5; font-weight: 750; }
.training-content { min-width: 0; }
.training-content .learning-head { margin-bottom: 34px; }
.training-content .learning-head h1 { font-size: clamp(2.2rem, 4vw, 3.4rem); }
.training-content .learning-head .eyebrow { margin-top: 0; }
.training-content .method-layout { display: block; }
.training-content .method-domain, .training-content .method-section { scroll-margin-top: 14px; }
.training-content .method-domain:first-of-type { margin-top: 26px; }
.training-related { border-top: 1px solid var(--line); padding: 20px 12px 0; }
.training-related .eyebrow { font-size: .65rem; }
.training-related a { display: block; margin: 12px 0; font-size: .79rem; text-underline-offset: 4px; }
.library-panel { margin: 0; padding-top: 26px; border-top: 1px solid var(--line); scroll-margin-top: 14px; }
.library-panel + .library-panel { margin-top: 48px; }
[data-training-ready] .library-panel + .library-panel { margin-top: 0; }
.library-panel > h2, .library-panel .lab-heading h2 { margin: 0 0 18px; font-size: clamp(1.55rem, 2.4vw, 2.1rem); }
.library-panel > .math-lab { margin: 0; padding: 0; border: 0; }
.library-panel .explore-question { margin: 0 0 24px; }
.library-panel .lab-layout { grid-template-columns: minmax(0, 1.65fr) minmax(220px, .95fr); }
.training-filters .exercise-filters { display: block; padding: 0 8px 0 0; margin: 0; background: none; }
.training-filters .filter-primary, .training-filters .filter-secondary { display: grid; grid-template-columns: minmax(0, 1fr); gap: 16px; }
.training-filters label { font-size: .78rem; }
.training-filters input, .training-filters select { font-size: .8rem !important; }
.training-filters .filter-more { margin: 16px 0; }
.training-filters .filter-reset { min-height: 44px; }
.training-show-results { display: none; }
.training-content [data-exercise-count] { scroll-margin-top: 64px; }
.training-content .exercise-result h2 a { text-decoration: underline; text-decoration-color: #c2c6ce; text-underline-offset: 4px; }
.training-content .exercise-result h2 a:hover { text-decoration-color: var(--coral-dark); color: var(--coral-dark); }
.training-content .method-choice { gap: 24px; }
.training-content .method-choice-end { gap: 18px; }
.desktop-nav { gap: .8rem; }
@media (min-width: 861px) and (max-width: 1320px) {
  .header-search .search-label, .header-search .kbd { display: none; }
  .header-inner { gap: 16px; }
  .desktop-nav { gap: .7rem; }
  .desktop-nav a { font-size: .79rem; }
}
@media (min-width: 861px) and (max-width: 1080px) {
  .header-support { display: none; }
  .training-workspace { grid-template-columns: 224px minmax(0, 1fr); gap: 32px; }
  .library-panel .lab-layout { grid-template-columns: minmax(0, 1fr); }
  .library-panel .lab-controls { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .library-panel .lab-controls .lab-readout { grid-column: 1 / -1; }
  .training-content .method-choice { grid-template-columns: minmax(0, 1fr); gap: 14px; }
  .training-content .method-choice-end { justify-content: space-between; }
}
@media (max-width: 860px) {
  .learning-page:has(.training-workspace) { padding-top: 14px; }
  .training-workspace { display: block; }
  .training-sidebar { z-index: 60; top: calc(var(--header-height) + 8px); margin-bottom: 28px; }
  .training-sidebar > summary { display: flex; align-items: center; gap: 12px; min-height: 52px; padding: 10px 14px; background: var(--white); border: 1px solid #bfc3ca; border-radius: 8px; cursor: pointer; list-style: none; font-size: .9rem; font-weight: 800; box-shadow: 0 3px 12px #101a2d0a; }
  .training-sidebar > summary::-webkit-details-marker { display: none; }
  .training-menu-context { font-weight: 600; color: var(--muted); }
  .training-menu-symbol { color: var(--coral-dark); }
  .training-menu-chevron { margin-left: auto; transition: transform .16s ease; }
  .training-sidebar[open] .training-menu-chevron { transform: rotate(180deg); }
  .training-menu-panel { position: absolute; inset: calc(100% + 6px) 0 auto; max-height: calc(100svh - var(--header-height) - 98px); padding: 16px; background: var(--paper); border: 1px solid var(--line); border-radius: 8px; box-shadow: 0 16px 35px #101a2d26; }
  .training-resource-label { display: none; }
  .training-nav { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 6px; }
  .training-nav a { display: flex; flex-direction: column; justify-content: center; gap: 5px; min-height: 68px; padding: 8px 3px; font-size: .77rem; }
  .training-nav .training-link-arrow { display: none; }
  .training-local { margin-top: 16px; padding-top: 16px; }
  .training-local-nav a { min-height: 46px; font-size: .85rem; }
  .training-content .learning-head h1 { font-size: clamp(2rem, 7vw, 3rem); }
  .training-content .learning-head { margin-bottom: 28px; }
  .training-content .method-domain, .training-content .method-section, .library-panel { scroll-margin-top: 64px; }
  .library-panel .lab-layout { grid-template-columns: minmax(0, 1fr); }
  .training-filters .filter-primary { grid-template-columns: 1fr; }
  .training-show-results { display: inline-flex; margin-top: 16px; }
  .mobile-nav { max-height: calc(100svh - var(--header-height)); overflow-y: auto; }
}
@media (prefers-reduced-motion: reduce) {
  .training-nav a, .training-local-nav a, .training-menu-chevron { transition: none; }
}
@media print {
  .training-sidebar { display: none; }
  .training-workspace { display: block; }
}
@media (max-width: 860px) {
  .method-layout { grid-template-columns: minmax(0, 1fr); gap: 30px; }
  .method-mobile-contents { display: block; }
  .method-mobile-contents a { display: block; margin: 12px 0; }
  .method-aside { max-height: none; }
  .method-aside nav { display: none; }
}
@media (max-width: 540px) {
  .method-example { padding-left: 14px; }
  .method-article .lab-controls { grid-template-columns: minmax(0, 1fr); }
  .induction-chain { flex-direction: column; align-items: flex-start; }
  .induction-chain > [aria-hidden] { transform: rotate(90deg); margin-left: 24px; }
}