:root{--paper:#f7f7f2;--ink:#171916;--rule:#babeb3;--blue:#254dff;--warm:#9c3b25}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:'Space Grotesk',system-ui,sans-serif;font-size:16px;line-height:1.55}[hidden]{display:none!important}a{color:var(--blue);text-underline-offset:3px}button,input,select{font:inherit}button,select{min-height:46px}button{border:1px solid var(--ink);padding:10px 20px;background:var(--paper);color:var(--ink);cursor:pointer}button:hover{background:#e9ebe2}button:disabled{opacity:.45;cursor:default}:focus-visible{outline:3px solid var(--blue);outline-offset:4px}.skip{position:absolute;top:-80px;left:20px;background:var(--ink);color:white;padding:12px;z-index:100}.skip:focus{top:10px}main{max-width:1140px;margin:auto;padding:40px 32px 24px}main,[id],h2{scroll-margin-top:95px}.intro{max-width:900px}.eyebrow{font-size:11px;font-weight:700;letter-spacing:.14em}h1{font-family:Anton,'Arial Narrow',Impact,sans-serif;font-weight:400;font-size:clamp(46px,6.5vw,86px);line-height:1.08;letter-spacing:-.015em;margin:16px 0 20px}h1 span{color:var(--blue)}.intro>p{font-size:18px;max-width:680px;margin-bottom:18px}.note{display:inline-block;border:1px solid var(--rule);padding:5px 10px;font-size:12px}.tabs{display:flex;border-bottom:1px solid var(--ink);margin-top:32px;gap:6px}.tabs button{border:0;border-bottom:3px solid transparent;padding:13px 18px}.tabs [aria-selected=true]{border-bottom-color:var(--blue);color:var(--blue);font-weight:700}section{padding-top:28px}h2{font-size:clamp(25px,3vw,36px);line-height:1.2;font-weight:600;letter-spacing:-.04em;margin:10px 0 22px}h2:focus{outline:none}h2:focus-visible{outline:3px solid var(--blue);outline-offset:5px}.visual{background:#ecefe5;border:1px solid var(--rule);position:relative;overflow:hidden}.visual svg{display:block;width:100%;height:auto;max-height:390px}.visual text{font-family:'Space Grotesk',system-ui,sans-serif;fill:var(--ink);font-size:17px}.visual .small{font-size:14px}.visual .blue{fill:var(--blue)}.caption{font-size:18px;max-width:760px;min-height:58px;margin:18px 0}.caption dfn{font-style:normal;font-weight:700}.step-nav{display:flex;align-items:center;justify-content:space-between;gap:12px;border-top:1px solid var(--rule);padding-top:18px;margin-top:22px}.step-nav button:last-child{background:var(--blue);color:white;border-color:var(--blue)}[data-step-progress]{font-size:13px;white-space:nowrap}.hint,.model-note{font-size:13px;color:#53584d}.replay{font-size:13px;min-height:44px}.controls{display:grid;grid-template-columns:1fr 1fr;gap:14px 32px;margin-top:20px}.controls label{grid-column:1}.controls input{grid-column:2}input[type=range]{width:100%;accent-color:var(--blue);min-height:44px}label{display:block;font-weight:600}select{width:100%;max-width:520px;border:1px solid var(--rule);background:var(--paper);padding:8px;margin:8px 0}#clinical-fill{max-width:520px;display:block}.value-row{border-top:1px solid var(--rule);padding:20px 0;display:grid;grid-template-columns:1fr 1fr;gap:8px 28px}.value-row h3{font-size:18px;margin:0}.value-row .reading{font-size:20px;font-weight:700}.value-row .status,.direction{font-size:13px}.value-row .citation{grid-column:1/-1;font-size:12px;color:#53584d}.gauge{width:100%;height:42px;display:block}.gauge .band{fill:#d1d8fd}.gauge .reference{stroke:#171916;stroke-width:2}.gauge .marker{stroke:var(--blue);stroke-width:4;transition:x1 .2s,x2 .2s}.direction{color:var(--warm);font-weight:600}#sources{padding-left:20px;font-size:13px}#sources li{margin:12px 0}footer{border-top:1px solid var(--ink);margin-top:46px;padding-top:20px;font-size:12px}.ghost{opacity:.3;stroke-dasharray:7 6}.legend{font-size:13px!important}summary{cursor:pointer;min-height:44px}#model-results{font-weight:600;padding:15px;border-left:3px solid var(--blue)}@media(max-width:620px){main{padding:28px 18px 20px}.intro>p{font-size:16px}h1{font-size:47px}.tabs{gap:0;margin-top:26px}.tabs button{font-size:13px;padding:10px 11px;flex:1}h2{margin-bottom:16px}.visual svg{min-height:235px}.caption{font-size:16px;margin:14px 0}.step-nav{margin-top:16px;padding-top:14px}.step-nav button{padding:9px 15px}.hint{font-size:11px}.value-row{grid-template-columns:1fr}.value-row .citation{grid-column:1}.controls{display:block}.controls label{margin-top:14px}main,[id],h2{scroll-margin-top:80px}}@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
@media(max-width:620px){.visual text{font-size:26px}.visual .small{font-size:22px}.visual .legend{font-size:22px!important}}
@media(max-width:620px){.step-nav{position:sticky;bottom:0;z-index:10;background:var(--paper);padding-bottom:12px;box-shadow:0 -8px 14px var(--paper)}}
/* Site top bar, matching the homepage's view A (Astra) bar. Scoped names so it cannot collide with lab.css or a lesson's CSS. */
.site-top{position:sticky;top:0;z-index:50;background:rgba(247,247,242,.96);border-bottom:1px solid #171916;-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);font-family:'Space Grotesk',system-ui,-apple-system,'Segoe UI',sans-serif}
.site-top-in{max-width:1600px;margin:0 auto;padding-inline:clamp(22px,4vw,64px);height:78px;display:flex;align-items:center;gap:28px}
.site-brand{font-weight:700;font-size:27px;letter-spacing:-.08em;color:#171916;text-decoration:none;white-space:nowrap}
.site-brand span{color:#254dff;padding-inline:5px}
.site-nav{margin-left:auto;display:flex;align-items:center;gap:26px}
.site-nav a{color:#171916;text-decoration:none;font-size:13px;white-space:nowrap}
.site-nav a:hover{color:#254dff}
.site-nav a[aria-current]{color:#254dff;font-weight:600;text-decoration:underline;text-decoration-thickness:2px;text-underline-offset:6px}
.site-top a:focus-visible{outline:3px solid #254dff;outline-offset:3px}
@media(max-width:850px){.site-top-in{height:70px}.site-nav{gap:17px}.site-nav a{font-size:12px}}
@media(max-width:620px){.site-top-in{height:66px;gap:15px}.site-brand{font-size:24px}.site-nav{gap:18px}.site-nav a{display:none}.site-nav a.site-nav-home,.site-nav a.site-nav-lab{display:block}}
@media print{.site-top{position:static}}