:root{color-scheme:light;--navy:#01017c;--cyan:#22a9f8;--ink:#20364d;--muted:#52677b;--line:#d7e6ef;--soft:#edf8ff;--blue:#006fb7}*{box-sizing:border-box}body{margin:0;background:white;color:var(--ink);font:16px/1.55 system-ui,-apple-system,sans-serif}main{max-width:1240px;margin:auto;padding:36px 32px 22px}header{padding-bottom:30px}.eyebrow,.control-kicker{text-transform:uppercase;letter-spacing:.11em;font-size:11px;font-weight:750;color:var(--navy);margin:0 0 13px}h1{font-size:clamp(36px,5.2vw,66px);line-height:1.04;letter-spacing:-.055em;font-weight:650;color:var(--navy);margin:0 0 22px}p{margin:0 0 16px}.intro{font-size:19px;color:var(--muted);margin:0}.workbench{display:grid;grid-template-columns:minmax(0,1.35fr) minmax(0,.75fr);gap:34px}.workbench>*{min-width:0}.section-line{display:flex;justify-content:space-between;align-items:start;gap:16px;margin-bottom:17px}.section-line h2{font-size:16px;margin:0;font-weight:650;color:var(--navy)}.section-line span{font-size:13px;white-space:nowrap;color:var(--muted)}svg{width:100%;height:auto;display:block}#bench{overflow:visible}.angle-readouts{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:12px;border-bottom:1px solid var(--line);padding:17px 0}.angle-readouts p{min-width:0;display:flex;align-items:center;gap:8px;font-size:13px;margin:0;flex-wrap:wrap}.angle-readouts strong{font-variant-numeric:tabular-nums;font-size:22px;color:var(--navy);margin-left:auto}.key{border:1px solid var(--navy);color:var(--navy);width:24px;height:24px;display:inline-flex;align-items:center;justify-content:center;border-radius:50%;font-weight:750}.key.outgoing{color:var(--blue);border-color:var(--blue)}.diagram-key{font-size:12px;color:var(--muted);margin:12px 0 21px;display:flex;align-items:center;gap:10px}.diagram-key>span:first-child{display:inline-block;flex:0 0 30px;border-top:2px dashed #697e90}.concept-buttons{display:flex;gap:8px;flex-wrap:wrap}.concept-buttons button{flex:1;min-width:75px;font-size:13px;padding:10px 7px}.concept-copy{padding:19px 0 0;min-height:140px}.concept-copy h3{font-size:17px;line-height:1.35;color:var(--navy);margin:0 0 8px}.concept-copy p{color:var(--muted);font-size:14px;margin:0}.controls{border-left:1px solid var(--line);padding-left:30px}.controls h2{font-size:25px;letter-spacing:-.025em;color:var(--navy);margin:0 0 17px}.index-buttons{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}button{font:inherit;min-height:46px;cursor:pointer;border:1px solid #b5cbdc;background:white;color:var(--navy);border-radius:11px;line-height:1.2;transition:none}button:hover{border-color:var(--navy);background:var(--soft)}button[aria-pressed=true]{color:white;background:var(--navy);border-color:var(--navy)}button:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--blue);outline-offset:4px}.index-buttons button{min-height:66px;font-size:28px;letter-spacing:-.02em;font-weight:650;font-variant-numeric:tabular-nums}.small{font-size:13px;color:var(--muted);margin:12px 0 0}.angle-control{margin-top:28px;padding-top:24px;border-top:1px solid var(--line)}label{display:flex;justify-content:space-between;gap:15px;align-items:center;font-size:15px;color:var(--navy);font-weight:650}output{font-size:24px;font-variant-numeric:tabular-nums}input[type=range]{width:100%;height:44px;display:block;margin:8px 0 0;accent-color:var(--navy);cursor:pointer}.presets{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px;margin-top:17px}.presets button{padding:10px 7px;font-size:12px}.finding{margin:26px 0 0;background:var(--soft);padding:21px 20px;border-radius:15px}.finding h3{font-size:22px;color:var(--navy);letter-spacing:-.02em;line-height:1.18;margin:0 0 12px}.finding p:not(.control-kicker){font-size:14px;margin-bottom:14px}.finding .fixed-condition{font-size:12px!important;padding-top:12px;border-top:1px solid #c5dfef;color:var(--muted);margin-bottom:0!important}.locator{display:grid;grid-template-columns:minmax(0,1fr);margin:20px 0 0}.locator svg{max-width:260px;margin:auto}.locator figcaption{font-size:12px;color:var(--muted)}.locator strong{color:var(--navy)}.model-limit{font-size:13px;color:var(--muted);border-top:1px solid var(--line);padding-top:21px;margin:25px 0}.model-limit strong{color:var(--navy)}.text-guide{padding:18px 0;border-top:1px solid var(--line);font-size:14px}.text-guide summary{min-height:44px;cursor:pointer;color:var(--navy);font-weight:650;display:list-item;padding:10px 0}.text-guide p{margin-top:14px;color:var(--muted)}footer{font-size:11px;color:var(--muted);border-top:1px solid var(--line);padding-top:16px}.static-fallback img{display:block;width:100%;max-width:640px;height:auto;margin:0 auto 22px}.static-fallback p{color:var(--muted);font-size:15px}.js .static-fallback{display:none}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;clip:rect(0,0,0,0);white-space:nowrap;border:0;overflow:hidden}[hidden]{display:none!important}main[data-concept=surface] .surface-highlight,main[data-concept=normal] .normal-highlight{opacity:.2}main[data-concept=ray] [data-ray$=Glow]{opacity:.36}
@media(max-width:700px){main{padding:26px 16px 18px}header{padding-bottom:25px}h1{font-size:44px}.intro{font-size:16px}.workbench{grid-template-columns:minmax(0,1fr);gap:21px}.controls{border-left:0;border-top:1px solid var(--line);padding:24px 0 0}.controls h2{font-size:25px}.section-line{gap:8px}.section-line h2{font-size:14px}.section-line span{font-size:12px}.angle-readouts{gap:8px}.angle-readouts p{font-size:12px;gap:6px}.angle-readouts strong{font-size:20px}.concept-copy{min-height:0}.concept-copy p{font-size:14px}.index-buttons{grid-template-columns:repeat(4,minmax(0,1fr));gap:7px}.index-buttons button{font-size:22px;min-height:59px}.angle-control{margin-top:24px}.presets button{font-size:13px}.finding{margin-top:23px}.locator{grid-template-columns:minmax(0,.85fr) minmax(0,1fr);align-items:center;gap:13px}.locator figcaption{font-size:12px}.model-limit{margin-top:22px}.text-guide{font-size:14px}}@media(max-width:350px){h1{font-size:38px}.section-line{display:block}.section-line span{display:block;margin-top:3px}.angle-readouts p{display:grid;grid-template-columns:auto minmax(0,1fr)}.angle-readouts strong{grid-column:2;margin-left:0}.index-buttons button{font-size:20px}.locator{grid-template-columns:minmax(0,1fr)}.locator svg{max-width:190px}.locator figcaption{font-size:13px}.concept-buttons{gap:6px}}@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}

/* Keep one set of controls beside the scene on desktop and around it on mobile. */
.optical-stage{grid-column:1;grid-row:1}.controls{grid-column:2;grid-row:1 / span 2}.concept-section{grid-column:1;grid-row:2}.concept-copy{min-height:0}
@media(max-width:700px){.workbench{gap:20px}.controls{display:contents}.index-control{grid-column:1;grid-row:1}.optical-stage{grid-column:1;grid-row:2}.angle-control{grid-column:1;grid-row:3;margin-top:0;padding-top:18px}.finding{grid-column:1;grid-row:4;margin-top:0}.concept-section{grid-column:1;grid-row:5}.locator{grid-column:1;grid-row:6;margin-top:0;padding-top:8px}.index-control .control-kicker{display:none}.index-control h2{font-size:19px;margin:0 0 12px;color:var(--navy)}.index-control .small{font-size:12px}.section-line{margin-top:5px}.angle-readouts{padding:12px 0}.diagram-key{margin-bottom:0}}