:root{--aqua:#00BFCB;--aqua-deep:#00707c;--navy:#071a2b;--blue:#0b5278;--teal:#0ea39b;--gold:#f2b84b;--ink:#172637;--muted:#607283;--paper:#fff;--mist:#edf5f7;--line:#d4e2e6;--danger:#a8323e;--ok:#157a55;--shadow:0 14px 38px rgba(7,26,43,.12)}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;color:var(--ink);background:var(--aqua);font:17px/1.68 Arial,Helvetica,sans-serif}button,input{font:inherit}button{cursor:pointer}.hidden{display:none!important}
.start-screen{position:fixed;inset:0;z-index:100;background:linear-gradient(135deg,#00BFCB,#00a3b0);display:grid;place-items:center;padding:1.25rem}.start-card{width:min(680px,100%);background:#fff;border-radius:24px;padding:clamp(1.5rem,5vw,3.2rem);box-shadow:0 30px 80px #0007;text-align:center}.brand-mark{display:inline-grid;place-items:center;width:74px;height:74px;border-radius:50%;background:var(--teal);color:#fff;font:bold 29px Georgia,serif}.eyebrow{margin:.65rem 0 .3rem;color:var(--teal);font-weight:800;letter-spacing:.13em;text-transform:uppercase;font-size:.76rem}.start-card h1{font:700 clamp(2rem,7vw,3.6rem)/1.05 Georgia,serif;margin:.25rem 0}.start-card p{color:var(--muted)}.field{text-align:left;margin:1.5rem auto;max-width:440px}.field label{font-weight:700;display:block;margin-bottom:.35rem}.field input{width:100%;padding:.85rem 1rem;border:2px solid var(--line);border-radius:10px}.primary,.secondary{border:0;border-radius:999px;padding:.82rem 1.25rem;font-weight:800}.primary{background:var(--gold);color:var(--navy)}.secondary{background:#fff;color:var(--blue);border:2px solid var(--blue)}.primary:hover,.primary:focus{filter:brightness(.95);transform:translateY(-1px)}
.topbar{position:sticky;top:0;z-index:40;background:#071a2bf7;color:#fff;padding:.55rem max(1rem,calc((100vw - 1180px)/2));display:flex;align-items:center;gap:1rem}.top-brand{font-weight:800;white-space:nowrap}.learner{margin-left:auto;font-size:.84rem;color:#dcebf0}.progress-track{height:7px;background:#29465b;flex:1;border-radius:99px;overflow:hidden}.progress-fill{height:100%;width:0;background:linear-gradient(90deg,var(--teal),var(--gold));transition:width .25s}.progress-label{font-size:.78rem;min-width:3rem;text-align:right}
.hero{color:#fff;background:linear-gradient(110deg,#0a3f5cf0,#00808cd6),var(--hero-image,url('media/source/biceps-brachii/IMG_4320.jpg')) center 42%/cover;padding:clamp(4rem,9vw,8rem) 1rem}.hero-inner{max-width:1120px;margin:auto}.hero h1{font:700 clamp(2.7rem,8vw,5.9rem)/.98 Georgia,serif;max-width:760px;margin:.2rem 0 1rem}.hero .lede{max-width:720px;font-size:clamp(1.05rem,2.5vw,1.35rem);color:#e2f2f5}.facts{display:flex;flex-wrap:wrap;gap:.55rem;margin-top:1.6rem}.fact{border:1px solid #ffffff55;background:#061827aa;border-radius:999px;padding:.42rem .82rem;font-size:.82rem}.section-nav{background:#fff;border-bottom:1px solid var(--line);padding:.7rem 1rem;overflow:auto;white-space:nowrap}.nav-inner{max-width:1120px;margin:auto}.section-nav a{display:inline-block;color:var(--blue);text-decoration:none;font-weight:700;font-size:.8rem;margin-right:1rem}
.crumb{display:block;background:#fff;padding:.55rem 1rem;font-size:.85rem}.crumb a{color:var(--blue);font-weight:700}.meta-row,.toc{display:flex;flex-wrap:wrap;gap:.55rem;margin-top:1rem}.chip,.toc a{border:1px solid #ffffff55;background:#061827aa;color:#fff;border-radius:999px;padding:.38rem .72rem;font-size:.78rem;text-decoration:none}.toc a:hover,.toc a:focus{background:var(--teal)}
.lesson{max-width:1120px;width:calc(100% - 1.5rem);margin:1.25rem auto;padding:clamp(1.6rem,5vw,3.4rem) clamp(1rem,4vw,2.4rem);background:#f6fdfe;color:var(--ink);border-radius:22px;box-shadow:var(--shadow)}.lesson h2{font:700 clamp(2rem,5vw,3.3rem)/1.1 Georgia,serif;color:var(--navy);margin:0 0 1.3rem}.lesson h3{color:var(--blue);margin-top:1.5rem}.section-kicker{color:var(--aqua-deep);font-weight:800;text-transform:uppercase;letter-spacing:.12em;font-size:.76rem}.grid-2,.grid-3{display:grid;gap:1.25rem}.card{background:#fff;border:1px solid var(--line);border-radius:16px;padding:clamp(1.1rem,3vw,1.7rem);box-shadow:var(--shadow)}.card h3:first-child{margin-top:0}.media{margin:1.4rem 0;background:#fff;border:1px solid var(--line);border-radius:18px;overflow:hidden;box-shadow:var(--shadow)}.media img,.media video{display:block;width:100%;max-height:650px;object-fit:contain;background:#08121c}.media .arrow-wrap{position:relative;display:block;width:fit-content;max-width:100%;margin:0 auto;background:#08121c;line-height:0}.media .arrow-wrap img{display:block;width:auto;max-width:100%;height:auto;max-height:650px;margin:0 auto;object-fit:fill}.media .arrow-wrap svg.arrows{position:absolute;left:0;top:0;width:100%;height:100%;pointer-events:none;overflow:visible}.media video{max-width:900px;height:auto;min-height:220px;margin:0 auto;visibility:visible;opacity:1}.media figcaption{color:var(--ink);padding:.9rem 1.1rem;font-size:.88rem}.media code{color:var(--aqua-deep)}.anatomy-table{width:100%;border-collapse:collapse}.anatomy-table th,.anatomy-table td{text-align:left;vertical-align:top;padding:.8rem;border-bottom:1px solid var(--line)}.anatomy-table th{color:var(--blue);width:10rem}.callout{border-left:6px solid var(--teal);background:#e2f4f3;padding:1rem 1.25rem;border-radius:10px}.callout.caution{border-color:var(--gold);background:#fff6df}.callout.danger{border-color:var(--danger);background:#fff0f1}.tag{display:inline-block;background:#dceff1;color:var(--blue);border-radius:99px;padding:.2rem .65rem;margin:.18rem;font-size:.82rem;font-weight:700}.summary{background:#e4f8fa;color:var(--ink);border:1px solid #9edfe5}.summary h3{color:var(--aqua-deep)}
.card-box{margin:1rem 0}.grid-media{display:grid;gap:1.25rem}.media-card{margin:1.4rem 0;background:#fff;border:1px solid var(--line);border-radius:18px;overflow:hidden;box-shadow:var(--shadow)}.media-card img,.media-card video{display:block;width:100%;max-height:650px;object-fit:contain;background:#08121c}.media-card figcaption{color:var(--ink);padding:.9rem 1.1rem;font-size:.88rem}.media-card code{color:var(--aqua-deep)}.callout.warn{border-color:var(--gold);background:#fff6df}.summary-grid{display:grid;gap:1rem}.narration{background:#fff;border:1px solid var(--line);border-radius:16px;padding:1rem 1.2rem}.narration summary{font-weight:800;color:var(--blue);cursor:pointer}.narration-text{white-space:pre-line;margin-top:1rem}.page-foot a{color:#fff;text-decoration:underline}
.quiz-question{border:0;margin:0 0 1.4rem;padding:0}.quiz-question legend{font-weight:800;margin-bottom:.55rem}.quiz-question label{display:block;background:#f7fbfc;border:1px solid var(--line);border-radius:9px;padding:.7rem .8rem;margin:.4rem 0}.quiz-question label:has(input:checked){border-color:var(--teal);background:#e5f6f5}.quiz-feedback{font-weight:700;margin-top:.4rem}.quiz-feedback.ok{color:var(--ok)}.quiz-feedback.bad{color:var(--danger)}.button-row{display:flex;flex-wrap:wrap;gap:.7rem}.score{font-size:1.15rem;font-weight:800;margin-top:1rem}.page-foot{background:var(--aqua-deep);color:#fff;padding:2rem 1rem;text-align:center;font-size:.85rem}
.page-head{max-width:1120px;width:calc(100% - 1.5rem);margin:1.25rem auto;padding:clamp(1.6rem,5vw,3rem) clamp(1rem,4vw,2.4rem);background:#f6fdfe;color:var(--ink);border-radius:22px;box-shadow:var(--shadow)}.page-head h1{color:var(--navy);font-family:Georgia,serif}.page-head .eyebrow{color:var(--aqua-deep)}.page-head .chip,.page-head .toc a{background:#0a3f5c;color:#fff;border-color:#0a3f5c}.page-head .toc a:hover,.page-head .toc a:focus{background:var(--aqua-deep)}
@media(min-width:760px){.grid-2{grid-template-columns:repeat(2,1fr)}.grid-3{grid-template-columns:repeat(3,1fr)}.media.split{display:grid;grid-template-columns:minmax(0,1.05fr) minmax(260px,.95fr);align-items:center}.media.split figcaption{padding:1.6rem}}
@media(max-width:600px){.media .arrow-wrap img{max-height:520px}body{font-size:16px}.top-brand{font-size:.72rem}.learner{display:none}.progress-track{min-width:60px}.anatomy-table th,.anatomy-table td{display:block;width:auto;padding:.55rem}.anatomy-table th{border-bottom:0;padding-bottom:0}.media img,.media video{max-height:520px}}
@media print{body{background:#fff;font-size:11pt}.start-screen,.topbar,.section-nav,.button-row,.quiz-feedback,.page-foot{display:none!important}.course-shell.hidden{display:block!important}.hero{background:none!important;color:#000;padding:0 0 1rem}.hero .lede{color:#333}.fact{border:1px solid #777;background:none}.lesson{max-width:none;width:auto;margin:0;padding:1rem 0;break-inside:avoid;border-color:#bbb;background:none;box-shadow:none;border-radius:0}.lesson h2{font-size:20pt}.card,.media{box-shadow:none;border:1px solid #aaa}.media{background:#fff}.media figcaption{color:#222}.media video{display:none}.quiz-question label{padding:.2rem;border:0}}