.learning-main { padding-top: 38px; padding-bottom: 70px; scroll-margin-top: 105px; }
.learning-main h1, .learning-main h2, .learning-main h3, .learning-main p { overflow-wrap: normal; }
.learning-main h1 { font-size: clamp(2.4rem, 4vw, 3.5rem); font-weight: 550; letter-spacing: -2px; line-height: 1.13; }
.learning-main h2 { font-size: 25px; font-weight: 600; letter-spacing: -.75px; line-height: 1.25; }
.learning-main h3 { font-size: 18px; font-weight: 600; line-height: 1.35; letter-spacing: -.3px; }
.learning-main p { line-height: 1.8; }
.learning-main a { color: var(--home-green); text-decoration: none; }
.learning-main .home-button { color: #fff; }
.learning-main a:focus-visible, .learning-main button:focus-visible, .learning-main summary:focus-visible { outline: 3px solid #77a882; outline-offset: 4px; }
.learning-main:focus { outline: none; }
.learning-hub-hero { display: grid; grid-template-columns: 1.3fr 1fr; gap: 90px; align-items: center; padding: 35px 0 60px; }
.learning-hub-hero h1 em { color: var(--home-green); font-family: Georgia, serif; font-weight: 400; }
.learning-hub-hero > div > p:not(.home-kicker) { max-width: 550px; margin: 23px 0; color: var(--home-muted); font-size: 15px; }
.learning-hub-visual { padding: 24px; border-radius: 8px; background: #edf2e8; }
.learning-hub-visual .anatomy-diagram { display: block; max-height: 285px; }
.learning-hub-visual > p { margin: 0; text-align: center; color: var(--home-muted); font-size: 12px; }
.learning-hub-visual > span { display: block; margin: 0; font-size: 9px; }
.learning-progress { display: grid; gap: 10px; max-width: 320px; margin-top: 24px; color: var(--home-muted); font-size: 11px; }
.learning-progress progress { width: 100%; height: 5px; border: 0; border-radius: 5px; background: #e3e9dc; accent-color: var(--home-green); }
.learning-progress progress::-webkit-progress-bar { border-radius: 5px; background: #e3e9dc; }
.learning-progress progress::-webkit-progress-value { border-radius: 5px; background: var(--home-green); }
.curriculum-heading { display: flex; justify-content: space-between; align-items: baseline; gap: 30px; padding-top: 32px; margin-bottom: 24px; border-top: 1px solid var(--home-line); }
.curriculum-heading > p { color: var(--home-muted); font-size: 11px; }
.curriculum-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
.curriculum-card { display: flex; align-items: center; gap: 22px; padding: 25px; border: 1px solid var(--home-line); border-radius: 6px; background: #fff; transition: border-color .15s, background .15s; }
.curriculum-card:hover { border-color: #9eb08a; background: #f1f4ed; }
.curriculum-card:last-child { grid-column: 1 / -1; background: #edf2e8; }
.curriculum-number { color: #819471; font-size: 34px; font-family: Georgia, serif; font-style: italic; }
.curriculum-meta { color: var(--home-muted); font-size: 9px; letter-spacing: .8px; }
.curriculum-card h3 { margin: 7px 0; color: var(--home-ink); }
.curriculum-card p { margin: 0; color: var(--home-muted); font-size: 12px; line-height: 1.6; }
.curriculum-card > .home-icon { width: 18px; height: 18px; margin-left: auto; }
.learning-glossary { display: grid; grid-template-columns: 1fr 1.2fr; gap: 75px; padding: 65px 0; margin-top: 60px; border-top: 1px solid var(--home-line); }
.learning-glossary > div:first-child > p:not(.home-kicker) { max-width: 350px; color: var(--home-muted); font-size: 14px; }
.learning-glossary details { border-bottom: 1px solid var(--home-line); }
.learning-glossary summary { display: flex; justify-content: space-between; padding: 15px 0; cursor: pointer; list-style: none; font-size: 14px; font-weight: 600; }
.learning-glossary summary::-webkit-details-marker { display: none; }
.learning-glossary summary > span { color: var(--home-green); }
.learning-glossary details > p { margin: 0 20px 15px 0; color: var(--home-muted); font-size: 13px; }
.learning-sources { padding: 40px 0; border-top: 1px solid var(--home-line); }
.learning-sources:focus { outline: none; }
#learningSources { scroll-margin-top: 110px; }
.learning-sources > p:not(.home-kicker) { max-width: 700px; color: var(--home-muted); font-size: 13px; }
.learning-sources > div { display: grid; grid-template-columns: 1fr 1fr; gap: 15px 35px; margin-top: 25px; }
.learning-sources a, .lesson-source-list a { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding-bottom: 10px; border-bottom: 1px solid var(--home-line); font-size: 12px; }
.learning-sources .home-icon, .lesson-source-list .home-icon { width: 15px; height: 15px; }
.learning-final-cta { display: flex; align-items: center; justify-content: space-between; gap: 30px; padding: 30px; margin-top: 30px; border-radius: 6px; background: #edf2e8; }
.learning-final-cta p { margin: 10px 0 0; color: var(--home-muted); font-size: 13px; }
.learning-breadcrumb { display: flex; flex-wrap: wrap; align-items: center; gap: 10px; margin-bottom: 35px; color: var(--home-muted); font-size: 11px; }
.lesson-layout { display: grid; grid-template-columns: 245px minmax(0, 1fr); gap: 65px; }
.lesson-sidebar { position: sticky; top: 115px; align-self: start; }
.lesson-menu > summary { display: none; }
.lesson-menu > .home-kicker { margin: 0 0 18px; }
.lesson-menu nav { display: grid; gap: 5px; }
.lesson-menu nav > a { display: flex; align-items: center; gap: 10px; min-height: 44px; padding: 11px 12px; border-left: 2px solid transparent; border-radius: 0 4px 4px 0; color: var(--home-muted); font-size: 12px; }
.lesson-menu nav > a > span { width: 20px; flex-shrink: 0; color: #8a9d7c; font-family: ui-monospace, monospace; font-size: 10px; }
.lesson-menu .home-icon { width: 15px; height: 15px; }
.lesson-menu nav > a:hover { background: #f0f4ea; }
.lesson-menu nav > a.is-active { border-left-color: var(--home-green); color: var(--home-green); background: #e9f0df; font-weight: 600; }
.sidebar-progress { margin: 20px 12px; color: var(--home-muted); font-size: 10px; }
.sidebar-practice { display: flex; align-items: center; gap: 10px; margin-top: 30px; padding-top: 22px; border-top: 1px solid var(--home-line); font-size: 11px; }
.sidebar-practice .home-icon { width: 16px; height: 16px; }
.lesson-article { min-width: 0; }
.lesson-heading h1 { font-size: clamp(2.1rem, 3.3vw, 3rem); }
.lesson-heading > p:not(.home-kicker) { margin: 24px 0; color: var(--home-muted); font-size: 16px; }
.lesson-goals { padding: 20px 24px; margin: 28px 0; border-left: 2px solid #b5c994; background: #eef3e7; }
.lesson-goals > span { display: flex; align-items: center; gap: 8px; color: var(--home-green); font-size: 12px; font-weight: 600; }
.lesson-goals .home-icon { width: 16px; height: 16px; }
.lesson-goals ul { display: grid; gap: 7px; margin: 13px 0 0; padding-left: 18px; color: var(--home-muted); font-size: 13px; line-height: 1.7; }
.lesson-visual { margin: 32px 0 42px; }
.lesson-principles { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; }
.lesson-principles > div { padding: 12px; border: 1px solid var(--home-line); border-radius: 5px; background: #f0f3e9; text-align: center; }
.lesson-principles .principle-diagram { max-width: 100%; margin: 5px auto 10px; }
.lesson-principles span { display: block; color: var(--home-green); font-size: 12px; }
.lesson-section { margin: 38px 0; scroll-margin-top: 105px; }
.lesson-section h2 { font-size: 24px; }
.lesson-section p { margin: 18px 0; color: #56645b; font-size: 15px; }
.lesson-reading { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 16px 26px; margin: 42px 0; padding: 22px 24px; border: 1px solid var(--home-line); border-left: 3px solid var(--home-green); border-radius: 5px; background: #f3f6ef; }
.lesson-reading h2 { grid-column: 1 / -1; margin: 0; font-size: 19px; }
.lesson-reading h3 { margin: 0 0 8px; color: var(--home-green); font-size: 12px; }
.lesson-reading p { margin: 0; color: var(--home-muted); font-size: 13px; line-height: 1.7; }

.learning-table-wrap { max-width: 100%; overflow-x: auto; margin-top: 22px; }
.learning-table-wrap table { width: 100%; border-collapse: collapse; text-align: left; font-size: 13px; line-height: 1.65; }
.learning-table-wrap th, .learning-table-wrap td { padding: 14px 16px; border-bottom: 1px solid var(--home-line); vertical-align: top; }
.learning-table-wrap thead th { color: var(--home-green); background: #edf2e8; font-weight: 600; }
.learning-table-wrap tbody th { min-width: 95px; color: var(--home-ink); font-weight: 600; }
.learning-table-wrap td { color: var(--home-muted); }
.learning-demo { display: grid; grid-template-columns: 1fr 1fr; gap: 30px; padding: 24px; border: 1px solid var(--home-line); border-radius: 7px; background: #f0f3e9; }
.learning-demo > div { min-width: 0; }
.learning-demo p { color: var(--home-muted); font-size: 13px; }
.learning-demo label { display: flex; justify-content: space-between; gap: 15px; margin: 23px 0 12px; color: var(--home-green); font-size: 12px; }
.learning-demo input[type="range"] { width: 100%; cursor: pointer; accent-color: var(--home-green); }
.learning-caption { margin: 12px 0 20px; color: var(--home-muted); font-size: 10px !important; line-height: 1.7; }
.anatomy-explorer .anatomy-diagram { display: block; height: auto; max-height: 290px; }
.chamber-region { fill: #d7e4d9; stroke: #8fa990; stroke-width: 1; }
.chamber-region.is-selected { fill: #b5cb89; stroke: var(--home-green); stroke-width: 2; }
.anatomy-explorer-controls { align-self: center; }
.chamber-buttons { display: grid; gap: 7px; }
.chamber-buttons button { min-height: 38px; padding: 8px 10px; border: 1px solid var(--home-line); border-radius: 4px; color: var(--home-green); background: #fff; text-align: left; font-size: 11px; }
.chamber-buttons button[aria-pressed="true"] { border-color: var(--home-green); background: #e7efda; }
#chamberDescription { min-height: 110px; padding-top: 23px; }
#chamberDescription h3 { font-size: 16px; }
#chamberDescription p { margin-bottom: 0; font-size: 12px; }
.learning-flow { display: flex; flex-wrap: wrap; justify-content: center; gap: 13px; padding: 18px 12px; color: var(--home-green); font-size: 11px; }
.learning-flow b { font-weight: 400; color: #96a982; }
.learning-atlas .atlas-tabs { grid-template-columns: repeat(3, 1fr); background: #edf2e8; }
.learning-atlas .atlas-tabs > button { padding: 12px; }
.learning-atlas .atlas-panel { gap: 22px; padding: 18px; }
.learning-atlas .atlas-description { padding: 3px 0; }
.learning-atlas .atlas-description h3 { font-size: 19px; }
.learning-atlas .atlas-description > p { font-size: 12px; }
.learning-atlas .atlas-visual { justify-content: center; }
.learning-atlas .atlas-visual > p { font-size: 8px; }
.learning-real-images { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-top: 25px; }
.learning-real-images figure { min-width: 0; overflow: hidden; margin: 0; border: 1px solid var(--home-line); border-radius: 6px; }
.learning-real-images figure > div { height: 230px; padding: 12px; background: #000; }
.learning-real-images img { display: block; width: 100%; height: 100%; object-fit: contain; }
.learning-real-images figcaption { padding: 12px 15px; color: var(--home-green); background: #edf2e8; font-size: 11px; }
.ef-demo { grid-template-columns: 1.25fr 1fr; }
.ef-demo h3 { font-size: 19px; }
.ef-result { align-self: center; padding: 20px; border-radius: 5px; background: #fff; text-align: center; }
.ef-result > span { font-size: 9px; letter-spacing: 1px; color: var(--home-muted); }
.ef-result > output { display: block; margin: 18px 0; color: var(--home-green); font-family: Georgia, serif; font-size: 55px; }
.ef-bar { overflow: hidden; height: 7px; border-radius: 5px; background: #edf2e8; }
.ef-bar > span { display: block; height: 100%; background: #a5bd7d; }
.ef-equation { font-family: ui-monospace, monospace; font-size: 10px !important; }
.quality-demo { align-items: center; }
.quality-demo figure { min-width: 0; margin: 0; }
.quality-demo img { display: block; width: 100%; height: 240px; padding: 8px; border-radius: 5px; object-fit: contain; background: #000; }
.quality-demo figcaption { margin-top: 10px; color: var(--home-muted); font-size: 9px; }
.lesson-reset { min-height: 38px; padding: 8px 12px; border: 1px solid #a4b497; border-radius: 4px; color: var(--home-green); background: #fff; font-size: 11px; }
.doppler-demo { align-items: center; }
.doppler-demo svg { width: 100%; height: auto; }
.doppler-demo svg text { text-anchor: middle; fill: var(--home-muted); font-family: ui-sans-serif, system-ui; font-size: 9px; }
.flow-toward, .flow-away { fill: none; stroke: #bc685d; stroke-width: 8px; stroke-linecap: round; stroke-linejoin: round; }
.flow-away { stroke: #638aa6; }
.is-inverted .flow-toward { stroke: #638aa6; }
.is-inverted .flow-away { stroke: #bc685d; }
.doppler-demo .home-button { font-size: 11px; }
.guided-case { display: flex; align-items: center; justify-content: space-between; gap: 25px; padding: 24px; border-radius: 6px; background: #edf2e8; }
.guided-case .home-kicker { display: block; margin-bottom: 10px; }
.guided-case p { margin-bottom: 0; color: var(--home-muted); font-size: 12px; }
.guided-case .home-button { flex-shrink: 0; }
.lesson-steps { display: grid; gap: 17px; padding-left: 22px; color: #56645b; font-size: 15px; line-height: 1.8; }
.lesson-steps li { padding-left: 8px; }
.student-template { padding: 24px; margin-top: 20px; border: 1px solid var(--home-line); border-radius: 5px; color: var(--home-green); background: #f0f3e9; font-family: ui-monospace, monospace; font-size: 12px; line-height: 2.3; white-space: pre-wrap; }
.lesson-takeaway { display: flex; align-items: flex-start; gap: 15px; padding: 22px; margin: 36px 0; border-left: 2px solid #b5c994; background: #eef3e7; }
.lesson-takeaway > .home-icon { width: 20px; height: 20px; color: var(--home-green); }
.lesson-takeaway strong { color: var(--home-green); font-size: 12px; }
.lesson-takeaway p { margin: 8px 0 0; color: var(--home-muted); font-size: 14px; }
.lesson-task { margin: 35px 0; }
.lesson-task > .home-kicker { margin-bottom: 12px; }
.lesson-task > p:last-child { color: var(--home-muted); font-size: 14px; }
.lesson-quiz { padding: 28px; margin: 30px 0; border: 1px solid #d6e0cc; border-radius: 6px; background: #fff; }
.lesson-quiz fieldset { min-width: 0; padding: 0; margin: 0; border: 0; }
.lesson-quiz legend { margin-bottom: 12px; padding: 0; color: var(--home-green); font-size: 20px; font-weight: 600; }
.lesson-quiz fieldset > p { margin: 5px 0 20px; font-size: 14px; }
.lesson-quiz label { display: flex; align-items: baseline; gap: 10px; padding: 12px; margin-bottom: 8px; border: 1px solid var(--home-line); border-radius: 4px; color: #56645b; cursor: pointer; font-size: 13px; line-height: 1.6; }
.lesson-quiz input { accent-color: var(--home-green); }
.lesson-quiz > button { margin-top: 13px; }
.quiz-feedback { padding: 15px; margin-bottom: 0; border-left: 2px solid #c89b68; color: #825321; background: #faf5eb; font-size: 13px; }
.quiz-feedback.is-correct { border-left-color: var(--home-green); color: var(--home-green); background: #eef3e7; }
.lesson-source-list { display: grid; gap: 13px; margin-top: 35px; }
.lesson-source-list > h2 { margin-bottom: 8px; font-size: 19px; }
.lesson-completion { padding: 25px 0; margin-top: 35px; border-top: 1px solid var(--home-line); }
.lesson-completion button { display: flex; align-items: center; gap: 9px; min-height: 42px; padding: 12px 16px; border: 1px solid var(--home-green); border-radius: 4px; color: var(--home-green); background: transparent; font-size: 12px; }
.lesson-completion button[aria-pressed="true"] { background: #e7efda; }
.lesson-completion .home-icon { width: 16px; height: 16px; }
.lesson-completion p { color: var(--home-muted); font-size: 10px; }
.lesson-pager { display: grid; grid-template-columns: 1fr 1fr; gap: 25px; padding-top: 25px; border-top: 1px solid var(--home-line); }
.lesson-pager > a { display: flex; flex-direction: column; gap: 12px; }
.lesson-pager > a:last-child { text-align: right; }
.lesson-pager span { color: var(--home-muted); font-size: 9px; letter-spacing: .8px; }
.lesson-pager strong { font-size: 14px; font-weight: 600; }
.lesson-all-sources { display: flex; align-items: center; justify-content: space-between; gap: 25px; margin-top: 38px; padding: 24px; border: 1px solid #cbd9c1; border-radius: 6px; background: #edf2e8; }
.lesson-all-sources h2 { margin: 0 0 8px; font-size: 20px; }
.lesson-all-sources p:not(.home-kicker) { margin: 0; color: var(--home-muted); font-size: 12px; line-height: 1.6; }
.lesson-all-sources .home-kicker { margin-bottom: 8px; }
.lesson-all-sources .home-button { flex-shrink: 0; }
.learning-not-found { padding-block: 100px; }
.learning-not-found h1 { margin-bottom: 35px; }
@media (max-width: 1050px) {
  .lesson-all-sources { flex-direction: column; align-items: flex-start; }
  .lesson-layout { grid-template-columns: 210px minmax(0, 1fr); gap: 35px; }
  .learning-hub-hero { gap: 40px; }
  .curriculum-card { padding: 20px; gap: 17px; }
  .guided-case { flex-direction: column; align-items: flex-start; }
}
@media (max-width: 840px) {
  #learningSources { scroll-margin-top: 150px; }
  .lesson-layout { grid-template-columns: 1fr; gap: 30px; }
  .lesson-sidebar { position: static; }
  .lesson-menu { border: 1px solid var(--home-line); border-radius: 5px; background: #f1f4ed; }
  .lesson-menu > summary { display: flex; justify-content: space-between; padding: 15px; cursor: pointer; list-style: none; color: var(--home-green); font-size: 12px; }
  .lesson-menu > summary::-webkit-details-marker { display: none; }
  .lesson-menu > p { margin-left: 15px; }
  .lesson-menu nav { padding: 0 8px; }
  .sidebar-practice { display: none; }
  .learning-breadcrumb { margin-bottom: 20px; }
  .learning-main { padding-top: 25px; }
  .learning-glossary { gap: 40px; }
  .learning-demo, .learning-atlas .atlas-panel { gap: 22px; }
}
@media (max-width: 600px) {
  .learning-main h1 { font-size: 36px; letter-spacing: -1.3px; }
  .learning-hub-hero { grid-template-columns: 1fr; gap: 30px; padding-top: 20px; padding-bottom: 35px; }
  .learning-hub-visual .anatomy-diagram { max-height: 220px; }
  .learning-hub-hero > div > p:not(.home-kicker) { font-size: 14px; }
  .curriculum-heading { flex-direction: column; gap: 10px; }
  .curriculum-heading p { margin-top: 0; }
  .curriculum-grid { grid-template-columns: 1fr; gap: 12px; }
  .curriculum-card { padding: 20px 17px; }
  .curriculum-card h3 { font-size: 17px; }
  .curriculum-number { font-size: 29px; }
  .learning-glossary { grid-template-columns: 1fr; gap: 25px; padding-block: 40px; margin-top: 40px; }
  .learning-sources > div { grid-template-columns: 1fr; }
  .learning-final-cta { flex-direction: column; align-items: flex-start; padding: 23px; }
  .learning-main h2 { font-size: 23px; }
  .lesson-heading > p:not(.home-kicker) { font-size: 15px; }
  .lesson-principles { gap: 6px; }
  .lesson-principles > div { padding: 7px 4px; }
  .lesson-principles .principle-diagram { height: 80px; }
  .lesson-principles span { font-size: 10px; }
  .lesson-section p, .lesson-steps { font-size: 14px; }
  .learning-demo { grid-template-columns: 1fr; padding: 18px; }
  .anatomy-explorer .anatomy-diagram { max-height: 235px; }
  .chamber-buttons { grid-template-columns: 1fr 1fr; }
  .chamber-buttons button { font-size: 10px; }
  #chamberDescription { min-height: 90px; }
  .learning-atlas .atlas-panel { grid-template-columns: 1fr; }
  .learning-atlas .atlas-tabs { grid-template-columns: repeat(2, 1fr); }
  .learning-atlas .anatomy-diagram { max-height: 235px; }
  .learning-real-images { gap: 10px; }
  .learning-real-images figure > div { height: 160px; padding: 6px; }
  .learning-real-images figcaption { padding: 9px; font-size: 9px; }
  .learning-table-wrap table { font-size: 11px; }
  .learning-table-wrap th, .learning-table-wrap td { padding: 10px; }
  .learning-table-wrap tbody th { min-width: 70px; }
  .lesson-goals, .lesson-quiz { padding: 20px; }
  .lesson-pager { gap: 17px; }
  .lesson-pager strong { font-size: 12px; }
  .lesson-pager span { font-size: 8px; }
  .student-template { padding: 16px; font-size: 11px; }
}
/* Definitions are readable without interaction and expand without leaving the lesson. */
.anatomy-definitions { margin: 38px 0; }
.anatomy-definition-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin-top: 20px; align-items: start; }
.anatomy-definition-grid details { border: 1px solid var(--home-line); border-radius: 5px; background: #fff; }
.anatomy-definition-grid summary { display: grid; grid-template-columns: 62px 1fr 12px; align-items: center; gap: 10px; padding: 17px; cursor: pointer; list-style: none; }
.anatomy-definition-grid summary::-webkit-details-marker { display: none; }
.anatomy-definition-grid summary span { font: 10px monospace; color: var(--home-green); }
.anatomy-definition-grid summary strong { font-size: 14px; font-weight: 600; }
.anatomy-definition-grid summary b { color: var(--home-green); font-weight: 400; }
.anatomy-definition-grid details[open] summary { border-bottom: 1px solid var(--home-line); background: #edf2e8; }
.anatomy-definition-grid details[open] summary b { transform: rotate(45deg); }
.anatomy-definition-grid dl { margin: 0; padding: 18px; }
.anatomy-definition-grid dt { margin-bottom: 5px; color: var(--home-green); font-size: 10px; font-weight: 600; text-transform: uppercase; letter-spacing: .6px; }
.anatomy-definition-grid dd { margin: 0 0 16px; font-size: 13px; line-height: 1.75; color: var(--home-muted); }
.anatomy-definition-grid dd:last-child { margin-bottom: 0; }
.source-review-date { font-size: 11px !important; color: var(--home-muted); }
.anatomy-primer-grid { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 22px; margin-bottom: 25px; }
.anatomy-primer-grid article { border: 1px solid var(--home-line); padding: 25px; border-radius: 5px; }
.anatomy-primer-grid h3 { font-size: 19px; font-weight: 550; margin: 18px 0 10px; }
.anatomy-primer-grid p { color: var(--home-muted); font-size: 14px; line-height: 1.8; margin: 0; }
.primer-shape { display: block; width: 45px; height: 48px; border-radius: 50% 50% 40% 40%; background: #dcebe3; }
.primer-cavity { background: #1a2b25; border: 6px solid #b5d5c2; }
.primer-wall { border: 10px solid #739e88; background: transparent; }
.primer-valve { width: 45px; height: 26px; border: 0; border-bottom: 3px solid #337361; border-radius: 0 0 50% 50%; }
@media (max-width:600px) { .anatomy-definition-grid, .anatomy-primer-grid { grid-template-columns: 1fr; } }