:root{--navy:#17366f;--navy2:#102a58;--blue:#17366f;--green:#35755d;--pale:#d8e8f0;--orange:#ee7d32;--ink:#1f2937;--muted:#667085;--line:#dfe5ef;--red:#c62828;--bg:#f6f8fc}*{box-sizing:border-box}body{margin:0;color:var(--ink);background:var(--bg);font:16px/1.55 'Open Sans',Arial,sans-serif}button,textarea{font:inherit}button,a{touch-action:manipulation}button{cursor:pointer}button:disabled{cursor:default;opacity:.55}button:focus-visible,a:focus-visible,textarea:focus-visible{outline:3px solid var(--orange);outline-offset:4px}[hidden]{display:none!important}a{color:var(--blue)}p{margin:0 0 16px}h1,h2,h3,.brand,.button,.scenario-tag{font-family:Montserrat,Arial,sans-serif}h1,h2,h3{color:var(--navy2);line-height:1.25;letter-spacing:-.035em;margin:0 0 18px}h1{font-size:clamp(35px,4.2vw,57px);max-width:730px}h2{font-size:30px}h3{font-size:20px;letter-spacing:-.02em}.skip{position:fixed;top:-100px;z-index:9;background:white;padding:15px}.skip:focus{top:0}.topbar{height:84px;background:white;display:flex;align-items:center;justify-content:space-between;padding:0 35px;border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:10px;text-decoration:none;color:var(--navy);font-size:12px;font-weight:bold;line-height:1.28;letter-spacing:.04em}.brand b{font-size:17px;letter-spacing:.11em}.product{display:flex;align-items:center;gap:18px;letter-spacing:.14em;font-size:11px;font-weight:bold;color:var(--navy)}.badge{border:1px solid var(--line);border-radius:4px;padding:5px 9px;color:var(--muted);letter-spacing:0;font-size:11px;font-weight:normal}.text-btn{border:0;background:none;color:var(--navy);padding:6px 0;font-size:13px;text-align:left}.text-btn:hover{text-decoration:underline}.app{display:grid;grid-template-columns:255px minmax(0,1fr);min-height:calc(100vh - 84px)}.sidebar{padding:34px 23px 24px;background:white;border-right:1px solid var(--line);display:flex;flex-direction:column}.overline{font-size:10px;letter-spacing:.16em;font-weight:bold;color:var(--muted);margin-bottom:17px}.nav-item{display:flex;align-items:center;gap:12px;width:100%;background:none;border:0;padding:12px 13px;color:var(--muted);text-align:left;font-size:14px;border-radius:5px}.nav-item.active{color:var(--blue);background:#edf3fa;font-weight:bold}.nav-item>span:first-child{font-size:20px;line-height:1}.side-divider{height:1px;background:var(--line);margin:28px 0}.sidebar h2{font-size:26px;line-height:1.15;margin-bottom:8px}.side-copy{color:var(--muted);font-size:11px;margin-bottom:30px}.step-nav{display:grid;gap:3px}.step-link{display:flex;align-items:center;gap:11px;text-align:left;border:0;background:none;color:var(--muted);padding:10px 0;font-size:12px}.step-link>span:first-child{width:24px;height:24px;border:1px solid var(--line);border-radius:50%;display:grid;place-items:center;font-size:10px;flex:none}.step-link.current{color:var(--blue);font-weight:bold}.step-link.current>span:first-child{background:var(--blue);color:white;border-color:var(--blue)}.step-link.done>span:first-child{color:var(--green);border-color:var(--green)}.sidebar-bottom{margin-top:auto;padding-top:60px}.sidebar-bottom p{font-size:12px;color:var(--muted)}.sidebar-bottom button{font-size:11px}main{padding:30px 4.2vw 45px;max-width:1550px;width:100%;margin:0 auto;outline:none}.breadcrumb{display:flex;gap:12px;align-items:center;color:var(--muted);font-size:11px;margin-bottom:34px}.breadcrumb>span:first-child{color:#a8b3c0}.save-status{margin-left:auto;font-size:10px;color:var(--muted)}.eyebrow{font-size:11px;letter-spacing:.15em;color:var(--blue);font-weight:bold;text-transform:uppercase;margin-bottom:15px}.lead{font-size:18px;color:var(--muted);max-width:620px;line-height:1.65}.lesson-header{display:flex;justify-content:space-between;align-items:center;margin-bottom:28px}.lesson-header p{margin:0}.tiny-steps{display:flex;gap:5px}.tiny-steps i{display:block;width:24px;height:3px;background:var(--line)}.tiny-steps i.filled{background:var(--blue)}.hero{display:grid;grid-template-columns:minmax(250px,.85fr) minmax(340px,1.15fr);gap:35px;align-items:center;padding:20px 0 34px}.hero h1{font-size:clamp(36px,4.5vw,62px)}.hero img{width:100%;height:auto;display:block;border-radius:12px;border:1px solid var(--line);aspect-ratio:3/2;object-fit:cover}.hero-art{position:relative}.art-caption{display:flex;align-items:center;gap:10px;margin-top:12px;color:var(--muted);font-size:11px}.art-caption span{width:18px;height:2px;background:var(--orange)}.meta{display:flex;flex-wrap:wrap;gap:20px;color:var(--muted);font-size:12px;margin:25px 0}.button{display:inline-flex;align-items:center;justify-content:center;gap:25px;border:1px solid var(--blue);background:var(--blue);color:white;padding:13px 22px;border-radius:10px;font-size:14px;font-weight:700;text-decoration:none;min-height:48px}.button:hover{background:var(--navy2)}.button.secondary{background:white;color:var(--navy);border-color:#c9d7eb}.button.secondary:hover{border-color:var(--navy)}.outcomes{display:grid;grid-template-columns:repeat(3,1fr);border-top:1px solid var(--line);border-bottom:1px solid var(--line);padding:26px 0;gap:30px}.outcome small{color:var(--orange);font-weight:bold;font-size:11px}.outcome h3{font-size:16px;margin:9px 0}.outcome p{font-size:13px;color:var(--muted);margin:0}.note{font-size:11px;color:var(--muted);margin-top:22px}.scene-layout{display:grid;grid-template-columns:minmax(0,1.25fr) minmax(290px,1fr);gap:28px;align-items:start}.scene{margin:0;background:white;border:1px solid var(--line);border-radius:12px;overflow:hidden}.scene img{width:100%;height:auto;display:block;aspect-ratio:3/2;object-fit:contain}.scene figcaption{padding:12px 15px;color:var(--muted);font-size:11px;border-top:1px solid var(--line)}.context{font-size:15px;line-height:1.6;max-width:900px}.question h2{font-size:23px;line-height:1.25}.options{display:grid;gap:10px}.option{display:flex;align-items:center;gap:13px;background:white;border:1px solid var(--line);border-radius:10px;text-align:left;padding:14px;color:var(--navy2);font-size:15px;line-height:1.45;min-height:65px}.option:hover:not(:disabled){border-color:var(--blue);background:#f3f7fc}.option:disabled{opacity:1}.option .letter{width:38px;height:38px;display:grid;place-items:center;border:1px solid var(--line);border-radius:50%;color:var(--navy);font:800 17px Montserrat,Arial,sans-serif;flex:none}.option.correct{border:2px solid var(--green);background:#eef5ed;padding:13px}.option.wrong{border:2px solid var(--red);background:#fff5f4;padding:13px}.option.selected{border-color:var(--blue)}.feedback{padding:19px 20px;border:1px solid var(--line);border-left:3px solid var(--blue);background:white;margin-top:19px;border-radius:5px;font-size:14px}.feedback.correct{border-color:var(--green);background:#f0f6ee}.feedback.wrong{border-color:var(--red);background:#fff7f6}.feedback h3{font-size:18px;margin-bottom:10px}.feedback p:last-child{margin:0}.hint{font-size:13px;border-left:3px solid var(--orange);background:#fff8f0;padding:12px 15px;margin-top:14px}.actions{display:flex;gap:12px;align-items:center;flex-wrap:wrap;justify-content:space-between;margin-top:28px;border-top:1px solid var(--line);padding-top:20px}.actions-right{display:flex;gap:10px}.step-content{max-width:1000px}.logic-layout{display:grid;grid-template-columns:1.1fr 1fr;gap:30px}.logic-tabs{display:flex;gap:8px;margin:0 0 18px;flex-wrap:wrap}.logic-tab{border:1px solid var(--line);background:white;color:var(--navy);padding:9px 13px;border-radius:4px;font-size:12px}.logic-tab.active{background:var(--blue);border-color:var(--blue);color:white}.logic-copy{padding:24px;background:white;border:1px solid var(--line);border-radius:6px;min-height:240px}.logic-copy .num{font-size:12px;color:var(--orange);display:block;margin-bottom:20px}.logic-copy p{font-size:16px;color:var(--muted)}.callout{margin-top:22px;border-left:3px solid var(--orange);padding:16px 18px;background:#fff8f0;font-size:14px}.sequence-grid{display:grid;grid-template-columns:minmax(260px,1fr) minmax(290px,1fr);gap:32px}.sequence-slots{display:grid;gap:10px}.slot{border:1px dashed #aab8c8;border-radius:5px;min-height:62px;display:flex;align-items:center;gap:17px;padding:13px 17px;background:white;font-size:14px}.slot b{font-size:11px;color:var(--blue)}.slot.empty{color:var(--muted)}.pool{display:grid;gap:10px}.pool button{border:1px solid var(--line);border-radius:5px;padding:17px;background:white;text-align:left;color:var(--navy);font-size:14px}.pool button:hover{border-color:var(--blue)}.pool button:disabled{background:#eef1f5}.scenario-tag{font-size:11px;border:1px solid var(--line);border-radius:4px;padding:5px 8px;display:inline-block;color:var(--muted);margin-bottom:16px}.transfer-grid{display:grid;grid-template-columns:1fr 1fr;gap:40px}.transfer-card{background:white;border:1px solid var(--line);border-radius:12px;padding:30px}.transfer-card strong{display:block;font-size:36px;color:var(--navy);line-height:1.1;margin:14px 0 25px}.checkpoint{max-width:780px}.check-row{display:flex;align-items:center;gap:15px;padding:18px 0;border-bottom:1px solid var(--line);font-size:15px}.check-row input{width:21px;height:21px;accent-color:var(--green);flex:none}.field-label{display:block;font-weight:bold;font-size:14px;color:var(--navy);margin:28px 0 10px}textarea{width:100%;border:1px solid #adb9c5;background:white;border-radius:5px;resize:vertical;padding:15px;min-height:110px;color:var(--ink)}.practice-plan{padding:23px;border:1px solid #bed0b6;background:#eff5ec;border-radius:6px;margin-top:25px}.practice-plan h3{font-size:19px}.practice-plan p{font-size:14px;margin:0}.summary-panel{background:var(--navy);color:white;border-radius:18px;padding:35px;margin:25px 0}.summary-panel h2{color:white;font-size:32px;max-width:650px;margin:0}.summary-panel .overline{color:#b8cbe1}.metrics{display:grid;grid-template-columns:repeat(3,1fr);gap:15px}.metric{border:1px solid var(--line);background:white;border-radius:6px;padding:20px}.metric strong{display:block;font-size:25px;color:var(--navy)}.metric span{font-size:12px;color:var(--muted)}.notes-view{max-width:800px}.note-card{background:white;border:1px solid var(--line);border-radius:12px;padding:27px}.note-card blockquote{margin:20px 0;padding-left:18px;border-left:2px solid var(--orange);font-size:17px;white-space:pre-wrap;overflow-wrap:anywhere}.pill{font-size:11px;color:var(--green);background:#edf5ed;padding:5px 9px;border-radius:4px}.small{font-size:12px;color:var(--muted)}.note-dot{width:5px;height:5px;border-radius:50%;background:var(--blue);margin-left:auto}dialog{border:1px solid var(--line);border-radius:10px;max-width:650px;padding:32px;color:var(--ink);font-size:14px;width:calc(100% - 24px)}dialog::backdrop{background:#0b1e37aa}.dialog-head{display:flex;justify-content:space-between;align-items:center}.icon-btn{border:0;background:none;font-size:29px;line-height:1;color:var(--navy)}hr{border:0;border-top:1px solid var(--line);margin:23px 0}.focus .sidebar{display:none}.focus .app{grid-template-columns:1fr}.focus main{max-width:1280px}.retry-note{font-size:12px;color:var(--muted)}
@media(min-width:1600px){main{padding-left:70px;padding-right:70px}}@media(max-width:1150px){.app{grid-template-columns:215px minmax(0,1fr)}.sidebar{padding:28px 18px}main{padding:28px}.hero{grid-template-columns:1fr;gap:25px}.hero-art{max-width:700px}.hero h1{max-width:620px}.scene-layout,.logic-layout{grid-template-columns:1fr}.question{max-width:750px}.scene{max-width:800px}.logic-copy{min-height:0}.transfer-grid{gap:22px}}@media(max-width:900px){.sequence-grid{grid-template-columns:minmax(0,1fr);gap:22px}}@media(max-width:760px){.topbar{height:72px;padding:0 18px}.product{font-size:9px;letter-spacing:.04em;gap:5px}.product .badge{display:none}.brand{font-size:9px}.brand b{font-size:13px}.brand img{width:34px;height:34px}.topbar>.text-btn{font-size:11px}.app{grid-template-columns:1fr}.sidebar{padding:16px 20px;border-right:0;border-bottom:1px solid var(--line)}.sidebar>.overline,.sidebar>.nav-item,.sidebar>.side-divider,.sidebar>.side-copy,.sidebar-bottom{display:none}.sidebar h2{font-size:14px;margin:0 0 13px}.sidebar h2 br{display:none}.step-nav{display:flex;justify-content:space-between;gap:5px}.step-link{font-size:0;padding:0}.step-link.current{font-size:11px}.step-link>span:first-child{width:24px;height:24px;font-size:10px}.step-link.current{gap:7px}main{padding:20px}.breadcrumb{margin-bottom:26px;font-size:10px;gap:8px}.save-status{font-size:9px}.hero{padding-top:8px;gap:25px}.hero h1{font-size:43px}.lead{font-size:16px}.outcomes{grid-template-columns:1fr;gap:19px;padding:23px 0}.outcome{display:grid;grid-template-columns:27px 1fr;column-gap:10px}.outcome small{grid-row:1/3;margin-top:7px}.outcome h3{margin:3px 0 5px}.outcomes p{grid-column:2}.sequence-grid,.transfer-grid{grid-template-columns:1fr;gap:22px}h1{font-size:35px}.lesson-header{margin-bottom:23px}.tiny-steps i{width:17px}.scene-layout{gap:22px}.actions{align-items:stretch;gap:18px}.actions-right{width:100%;flex-wrap:wrap}.actions-right .button{flex:1}.metrics{grid-template-columns:1fr}.metric{display:flex;align-items:center;gap:15px}.metric strong{font-size:22px}.summary-panel{padding:25px}.summary-panel h2{font-size:28px}.transfer-card{padding:23px}.context{font-size:14px}.option{min-height:70px}.note-card{padding:21px}.logic-tabs{gap:6px}.logic-tab{padding:9px 11px}.focus .sidebar{display:none}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;animation:none!important;transition:none!important}}
/* Detailed observation explanation */
.observation-demo{background:white;border:1px solid var(--line);border-radius:12px;overflow:hidden;margin-top:28px}.demo-main{display:grid;grid-template-columns:minmax(280px,.9fr) minmax(300px,1fr);align-items:stretch}.demo-visual{background:#f9f8f4;border-right:1px solid var(--line);position:relative}.demo-road{display:block;width:100%;height:550px}.demo-map-note{font-size:10px;color:var(--muted);text-align:center;background:#fffdf8;border-top:1px solid var(--line);padding:10px;margin:0}.demo-explanation{padding:36px 30px;display:flex;flex-direction:column;justify-content:center}.demo-explanation h2{font-size:30px;line-height:1.15;min-height:70px}.demo-description{font-size:16px;line-height:1.7;color:var(--ink)}.demo-cue{margin-top:14px;background:#fff7ed;border-left:3px solid var(--orange);padding:16px 17px;font-size:14px}.demo-cue strong{font-size:10px;color:#9e490a;text-transform:uppercase;letter-spacing:.09em}.demo-cue p{margin:8px 0 0}.demo-progress{height:3px;background:#e9edf2;margin-top:30px;overflow:hidden}.demo-progress span{display:block;width:0;height:100%;background:var(--blue)}.demo-status{margin:9px 0 0;min-height:19px}.demo-controls{display:flex;justify-content:center;align-items:center;flex-wrap:wrap;gap:12px;padding:21px;border-top:1px solid var(--line)}.demo-controls .button{font-size:12px;gap:10px}.demo-controls .text-btn{font-size:12px;margin-left:8px}.demo-transcript{border-top:1px solid var(--line);padding:17px 25px;font-size:13px}.demo-transcript summary{color:var(--navy);cursor:pointer}.demo-transcript ol{padding-left:25px;max-width:850px}.demo-transcript li{padding:13px 0;border-bottom:1px solid var(--line)}.demo-transcript button{background:none;border:0;padding:3px 0;font-size:15px;color:var(--blue);font-weight:bold;text-align:left}.demo-transcript button[aria-current]{text-decoration:underline}.demo-transcript li p{color:var(--muted);margin:6px 0 0;font-size:13px}
@media(max-width:1000px){.demo-main{grid-template-columns:1fr}.demo-visual{border-right:0;border-bottom:1px solid var(--line)}.demo-road{height:460px}.demo-explanation{padding:25px}.demo-explanation h2{min-height:0}.demo-description{max-width:680px}.demo-cue{margin-top:8px}}@media(max-width:500px){.demo-road{height:400px}.demo-explanation{padding:22px 18px}.demo-explanation h2{font-size:26px}.demo-description{font-size:15px}.demo-controls{gap:8px;padding:15px 12px}.demo-controls .button{padding:11px 13px;font-size:11px;min-height:44px}.demo-controls .text-btn{width:100%;text-align:center;margin:4px 0 0}.demo-transcript{padding:16px 18px}.demo-map-note{font-size:9px}}
/* Observe → stop → choose → animated feedback */
.animated-question-layout{display:grid;grid-template-columns:minmax(0,1.1fr) minmax(290px,1fr);gap:28px;align-items:start}.question-animation{margin:0;border:1px solid var(--line);border-radius:12px;background:white;overflow:hidden;scroll-margin-top:18px}.question-movie{position:relative;background:#f9f8f4}.question-road{width:100%;height:440px;display:block}.movie-state{position:absolute;top:14px;left:15px;background:white;border:1px solid var(--line);padding:6px 10px;font-size:9px;letter-spacing:.09em;color:var(--navy);font-weight:bold;border-radius:4px}.movie-caption{border-top:1px solid var(--line);background:#f0f4f8;margin:0;padding:16px 18px;font-size:16px;line-height:1.45;font-weight:bold;color:var(--navy);min-height:78px}.movie-controls{display:flex;gap:19px;align-items:center;flex-wrap:wrap;padding:12px 17px;border-top:1px solid var(--line)}.movie-controls .text-btn{font-size:12px;min-height:30px}.movie-controls button[data-movie-action="previous"],.movie-controls button[data-movie-action="next"]{padding:4px 9px;font-size:19px}.movie-legend{font-size:10px;line-height:1.7;color:var(--muted);padding:0 17px 13px;margin:0}.intention-key{display:inline-block;width:21px;border-top:2px dashed #465565;vertical-align:middle;margin-right:6px}.scenario-details{font-size:12px;margin-top:17px;margin-bottom:15px;color:var(--muted)}.scenario-details summary,.feedback summary{cursor:pointer;color:var(--navy)}.scenario-details p{margin-top:12px}.animated-question-layout .question>h2{font-size:26px}.animated-question-layout .scenario-tag{margin-bottom:13px}.animated-question-layout .option:disabled:not(.wrong):not(.correct){opacity:.65}.animated-question-layout .option.correct:disabled,.animated-question-layout .option.wrong:disabled{opacity:1}
@media(max-width:1000px){.animated-question-layout{grid-template-columns:1fr}.question-road{height:430px}.question-animation{max-width:740px}.animated-question-layout .question{max-width:740px}}@media(max-width:500px){.question-road{height:350px}.movie-caption{font-size:14px;min-height:75px;padding:13px 15px}.movie-state{font-size:8px;top:10px;left:10px}.movie-controls{gap:15px;padding:9px 14px}.movie-controls .text-btn{font-size:11px}.animated-question-layout .question>h2{font-size:23px}.animated-question-layout{gap:24px}}

.movie-attention{display:block;font-size:12px;font-weight:normal;margin-top:8px;color:var(--navy)}

.lesson-footer{display:flex;justify-content:space-between;align-items:center;gap:20px;border-top:1px solid var(--line);background:white;padding:19px 35px;font-size:12px}.lesson-footer a{color:var(--navy);text-decoration:none}.lesson-footer a:hover{text-decoration:underline}.lesson-footer .text-btn{font-size:12px}@media(max-width:600px){.lesson-footer{padding:18px 20px;flex-wrap:wrap;gap:10px}}

/* Shared DTD typography and comfortable review controls. */
.text-btn{min-height:44px;display:inline-flex;align-items:center}
.step-title{min-width:0}.sidebar,.question,.hero>section,.demo-explanation{min-width:0}
.hero img{border-radius:12px}.hero h1{line-height:1.12}
.eyebrow{color:var(--navy);font-family:Montserrat,Arial,sans-serif}
.overline,.breadcrumb,.save-status,.side-copy,.note,.small,.art-caption,.movie-legend,.scenario-details{font-size:12px}
.demo-cue strong{font-size:12px;color:#8b481f}.demo-transcript summary{min-height:44px;padding:10px 0}
.demo-transcript button{min-height:44px}.movie-controls .text-btn{min-height:44px;font-size:13px}
.movie-controls button[data-movie-action="previous"],.movie-controls button[data-movie-action="next"]{min-width:44px}
.movie-state{font-size:11px;letter-spacing:.04em}.demo-controls .button{font-size:13px}
@media(max-width:760px){
 .topbar{gap:10px;flex-wrap:wrap;height:auto;min-height:76px;padding:12px 18px}
 .brand{font-size:10px;flex-shrink:0}.brand b{font-size:14px}.topbar>.text-btn{font-size:12px;margin-left:auto}
 .product{font-size:10px;order:3;flex-basis:100%;justify-content:center}
 .sidebar h2{font-size:16px;line-height:1.3;margin-bottom:10px}
 .step-nav{position:relative;display:grid;grid-template-columns:repeat(6,minmax(0,1fr));gap:4px;padding-bottom:29px}
 .step-link,.step-link.current{font-size:0;min-width:0;min-height:44px;padding:0;justify-content:center;gap:0}
 .step-link>span:first-child{font-size:12px;width:28px;height:28px}
 .step-title{display:none}.step-link.current .step-title{display:block;position:absolute;left:0;right:0;bottom:0;font-size:13px;line-height:1.4;color:var(--navy)}
 .breadcrumb{font-size:12px;flex-wrap:wrap;gap:6px;margin-bottom:24px}.save-status{font-size:12px}
 .hero h1{font-size:clamp(34px,9vw,43px)}.meta{gap:12px;font-size:13px}
 .context,.outcome p,.option,.pool button,.slot{font-size:15px}
 .art-caption,.note,.small,.scenario-details,.movie-legend,.movie-attention{font-size:13px}
 .movie-state{font-size:11px}.movie-controls{gap:10px}.movie-controls .text-btn{font-size:13px}
 .demo-controls .button{font-size:13px;min-height:44px;padding:11px 15px}
 .demo-controls .text-btn{font-size:13px;justify-content:center}
 .actions-right{gap:10px}.actions-right .button{min-width:0;flex:1 1 150px}
 .lesson-header{gap:12px;flex-wrap:wrap}.lesson-header .eyebrow{font-size:12px}
}

/* Preserve intrinsic image proportions instead of the HTML height attribute. */
.hero-art,.scene{min-width:0}
@media(max-width:760px){
 .hero img,.scene img{height:auto;max-height:220px;max-height:min(30svh,220px);object-fit:contain;background:var(--bg)}
 .question-road{height:260px;height:clamp(220px,38svh,300px)}
 .demo-road{height:280px;height:clamp(240px,40svh,320px)}
}

/* Named mobile navigation and controls attached to their diagram. */
.demo-visual{align-self:start}.demo-focus{margin:0;padding:10px 16px;background:#fff4df;border-top:1px solid var(--line);color:var(--navy2);font-weight:700;font-size:14px;line-height:1.4}
.demo-controls{padding:14px 12px;gap:8px}.demo-controls button,.movie-controls button{min-width:44px;min-height:44px}
.demo-controls .text-btn{justify-content:center}.step-title{overflow-wrap:anywhere}
@media(max-width:760px){
 .step-nav{grid-template-columns:repeat(2,minmax(0,1fr));gap:4px 10px;padding-bottom:0}
 .step-link,.step-link.current{font-size:12px;gap:8px;padding:6px 0;min-height:48px;justify-content:flex-start;line-height:1.3;align-items:center}
 .step-link .step-title,.step-link.current .step-title{display:block;position:static;font-size:12px;line-height:1.3;color:inherit}
 .step-link>span:first-child{flex:none}.sidebar{padding-top:12px;padding-bottom:12px}
 .demo-explanation{padding-top:20px}.demo-controls .button{flex:1 1 80px;padding:10px 8px;font-size:12px;gap:4px}
 .demo-controls .text-btn{width:100%;margin:0}.movie-controls .text-btn{padding-left:8px;padding-right:8px}
 main{padding-top:16px}.breadcrumb{margin-bottom:18px}.lesson-header{margin-bottom:18px}
}

/* Shared intro artwork: image fills its own 3:2 bounds, without a separate frame. */
.hero-art{width:100%}
.hero-art>img{display:block;width:100%;height:auto;aspect-ratio:3/2;max-height:none;object-fit:cover;border:0;border-radius:10px;background:none}

/* Readable lesson reference content remains in HTML independently of player state. */
.lesson-reference{max-width:860px;margin-top:48px;padding-top:30px;border-top:1px solid var(--line)}
.lesson-reference h2{font-size:26px}.lesson-reference h3{font-size:19px;margin-top:25px}.lesson-reference p{font-size:15px}
.lesson-reference details{border-top:1px solid var(--line);padding:12px 0}.lesson-reference summary{min-height:44px;display:list-item;cursor:pointer;color:var(--navy2);font-weight:600;font-size:15px;padding:10px 0}.lesson-reference details p{margin:8px 0 12px}
.lesson-reference .small{font-size:12px}.related-lesson{display:inline-block;font-size:14px;line-height:1.6;margin-top:8px;padding:8px 0}