:root{font:15px system-ui,-apple-system,sans-serif;color:#243c47;background:#f5f7f6;--accent:#167e79;--line:#d6dddd}*{box-sizing:border-box}body{margin:0}button,input,select{font:inherit;color:inherit;border:1px solid #c5ced1;border-radius:5px;background:white;min-height:34px}button,select{padding:6px 10px}button{cursor:pointer}button.primary{background:var(--accent);color:white;border-color:var(--accent)}:focus-visible{outline:2px solid var(--accent);outline-offset:2px}header{max-width:1160px;margin:auto;padding:6px 20px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);font-size:.85rem}header>div{display:flex;gap:8px}a{color:var(--accent)}main{max-width:1160px;margin:auto;padding:8px 20px}.heading{display:flex;align-items:baseline;justify-content:space-between;gap:12px;margin-bottom:8px}h1{font-size:1.4rem;margin:0;letter-spacing:-.03em}h2{font-size:.95rem;margin:0}.heading p{margin:0;font-size:.88rem;color:#617079}.workspace{background:white;border:1px solid #ccd6d8;border-radius:9px;overflow:hidden}.toolbar{display:flex;align-items:center;gap:8px;padding:8px 16px;background:#f7fafa;font-size:.85rem}#status{margin-left:auto;font-weight:550;color:#167e79}.bench{background:linear-gradient(#fafcfc,#fff)}svg{display:block;width:100%;color:#243c47}#rig{height:295px;touch-action:none}svg text{font:14px system-ui,sans-serif;fill:currentColor}svg .load-label{font-size:20px;font-weight:550}svg .drag-target{cursor:grab}svg .drag-target:focus-visible{outline:none;filter:drop-shadow(0 0 3px #168c88)}#instruction{margin:0 16px 8px;font-size:.86rem;color:var(--accent);min-height:21px}.settings{display:flex;justify-content:space-between;gap:10px;margin:0 16px}.settings label{display:flex;align-items:center;gap:8px;font-size:.85rem}.settings input{width:64px;padding:5px}.small{font-size:.78rem;color:#617079;margin:7px 16px 9px}.bottom{display:grid;grid-template-columns:1fr 1fr;gap:22px;border-top:1px solid var(--line);padding:13px 16px;background:#fcfdfd}.answers{display:flex;align-items:end;gap:8px;margin-top:8px}.answers label{display:grid;grid-template-columns:80px auto;gap:4px;font-size:.78rem;align-items:center}.answers label>span:first-child{grid-column:1/-1}.answers input{width:80px;padding:5px}.answers button{font-size:.83rem}#feedback{font-size:.82rem;margin:6px 0;line-height:1.5}.good{color:#167e79}.bad{color:#a04c38}details{font-size:.8rem;line-height:1.5}summary{cursor:pointer}#help summary{color:var(--accent)}#help p{margin:6px 0}.records-heading{display:flex;align-items:center;justify-content:space-between;gap:8px}.records-heading button{font-size:.78rem;min-height:30px}table{width:100%;border-collapse:collapse;font-size:.8rem;margin-top:8px}th,td{text-align:left;border-bottom:1px solid #e7eded;padding:5px}th{font-weight:500;color:#617079}#readings{display:flex;gap:20px;border-top:1px dashed var(--line);padding:8px 16px;font-size:.82rem;font-variant-numeric:tabular-nums}#readings span{flex:1}footer{display:flex;justify-content:space-between;align-items:start;gap:20px;padding-top:8px}footer details{max-width:880px}footer p{line-height:1.6}footer button{font-size:.8rem}[hidden]{display:none!important}body.embed header>a{display:none}body.embed header{justify-content:flex-end}@media(max-width:700px){header{padding:5px 12px}main{padding:12px}.heading{display:block}.heading p{margin-top:6px}h1{font-size:1.25rem}.toolbar{padding:9px;flex-wrap:wrap}#status{width:100%;margin-left:0;font-size:.85rem}#rig{height:auto;min-height:165px}#rig .load-label{font-size:26px}#instruction{margin:8px 10px}.settings{margin:0 10px;flex-direction:column;gap:7px}.settings label>span:first-child{width:72px}.settings input{width:75px}.settings button,button,input,select{min-height:40px}.small{margin:9px 10px}.bottom{display:block;padding:12px}.comparison{border-top:1px solid var(--line);margin-top:14px;padding-top:12px}.answers{flex-wrap:wrap}.answers label{grid-template-columns:85px auto}.answers input{width:85px}.answers button{margin-top:7px}.records-heading{flex-wrap:wrap}#readings{display:block;padding:10px}#readings span{display:block;margin:4px 0}footer details{max-width:calc(100% - 65px)}}

/* R2: stable physical balance acquires the observation; calculation is optional. */
.workspace{background:transparent;border:0;border-radius:0;overflow:visible}.bench{background:transparent}.toolbar{background:transparent;padding:6px 0}.settings{margin:0;gap:16px}.settings label{font-size:.9rem}.settings input{font-variant-numeric:tabular-nums}#instruction{margin:0 0 10px;font-size:.95rem;line-height:1.5}.small{margin:8px 0 12px;font-size:.85rem;line-height:1.45}.bottom{padding:12px 0;background:transparent;grid-template-columns:minmax(0,1fr) minmax(0,1.2fr)}#result-summary{font-size:1rem;line-height:1.65;margin:0;color:#315e53}#practice-panel{margin-top:14px;border-top:1px solid var(--line);padding-top:12px}table{font-size:.95rem;font-variant-numeric:tabular-nums}th{font-size:.875rem;font-weight:600}td{line-height:1.55;padding:7px 6px}td:first-child small{display:block;font-size:.8rem;color:#617079}.new-run td{background:#dcebc9}.records-heading button{font-size:.85rem;min-height:36px}#practice-toggle{border:0;padding:4px 0;background:transparent;color:var(--accent);text-decoration:underline;text-underline-offset:4px;font-size:.85rem}footer{align-items:center;flex-wrap:wrap}footer details{flex:1}#readings{font-size:.9rem;padding-inline:0}.answers label{font-size:.875rem}#feedback{font-size:.9rem}#rig text[style*="font-size:11px"]{font-size:18px!important}
@media(max-width:700px){.settings{gap:6px}.settings label{font-size:.875rem}.settings label>span:first-child{width:76px}.small{font-size:.85rem}.bottom{padding:12px 0}.comparison{margin-top:12px;padding-top:12px}.records-heading{align-items:center}table{font-size:.9rem}th{font-size:.85rem}.heading p{font-size:.9rem}.toolbar #status{min-height:22px}#practice-toggle{flex-basis:100%;text-align:left}footer details{max-width:none}#rig{min-height:175px}}
@media(max-width:700px){#rig text:not([style]){font-size:26px}#rig .load-label{font-size:34px!important}#rig text[style*="font-size:11px"],#rig text[style*="font-size:18px"]{font-size:26px!important}}
/* R3: one apparatus, nearby readings, compact precision drawer and trial-led reasoning. */
.heading{align-items:center}.heading p{margin-left:auto}.heading #reset{flex-shrink:0;min-height:40px}header{border-bottom:0}.toolbar{gap:8px}#rig{height:280px}#precision{margin:4px 0 8px}#precision summary{color:var(--accent);font-size:.9rem}#precision .settings{margin-top:8px;justify-content:flex-start;gap:28px}.small{margin:7px 0 9px}#instruction{font-size:.94rem;min-height:24px;margin:0 0 6px}.bottom{grid-template-columns:minmax(0,1.35fr) minmax(0,1fr);gap:30px;padding-top:10px}#result-summary{font-size:1rem;line-height:1.4;font-weight:600}#explanation p{font-size:.95rem;line-height:1.5;margin:7px 0}.working{font-variant-numeric:tabular-nums;font-size:.94rem;line-height:1.7;margin:7px 0}.explain-nav{display:flex;gap:8px;margin-top:8px}table{margin-top:6px;font-size:.9rem}td{padding:5px 4px;line-height:1.4}th{font-size:.84rem}td button{border:0;background:transparent;color:var(--accent);min-height:25px;padding:0;text-decoration:underline;text-underline-offset:3px}.records-heading button{min-height:34px}#readings{padding:6px 0;font-size:.875rem;line-height:1.45}.position-label{font-size:20px;fill:#315e53}.arm-label{font-size:20px}.pivot-label{font-size:20px}button:hover{background:#edf3f1}button.primary:hover{background:#116860}button:disabled{opacity:.5;cursor:default}::selection{background:#cce7dd;color:#173c33}input{caret-color:var(--accent)}
@media(max-width:700px){.heading{display:grid;grid-template-columns:1fr auto}.heading p{grid-column:1/-1;margin:5px 0}.heading #reset{grid-column:2;grid-row:1}#rig{height:auto;min-height:175px}#precision .settings{flex-direction:column;gap:7px}.bottom{display:block}.comparison{margin-top:12px}.working{font-size:.875rem}.toolbar{flex-wrap:wrap}#instruction{min-height:44px}#rig .position-label{font-size:24px}#rig .arm-label{font-size:22px}}
.heading-actions{display:flex;gap:7px;align-items:center}.heading-actions button{white-space:nowrap}body.embed header{display:none}.heading{gap:14px;margin-bottom:6px}.heading p{font-size:.85rem}.bottom .working{margin:5px 0;line-height:1.6}.explain-nav{margin-top:6px}#explanation p{margin:6px 0}
@media(max-width:700px){.heading-actions{grid-column:2;grid-row:1}.heading-actions #guide{display:none}.heading-actions button{padding-inline:7px}.heading #reset{grid-row:auto;grid-column:auto}h1{font-size:1.15rem}.heading p{margin:4px 0}.heading{gap:5px}}

/* The formal Header forwards language and gesture to these existing controls. */
body.embed .heading-actions #guide,body.embed .heading-actions #language{display:none}

.key-hint{font-size:12px;color:var(--muted);margin:0 0 10px}