.lesson-head{padding:30px 0 24px}.lesson-head h1{font-size:clamp(30px,4vw,44px);max-width:940px;margin-top:15px}.lesson-head p{max-width:820px;color:var(--muted);margin-top:16px}.lesson-crumb{font-size:14px;text-underline-offset:4px}.lesson-meta{display:flex;gap:10px;flex-wrap:wrap;margin-top:18px}.lab-section{background:var(--soft);padding:28px 0 44px}.lab{border:1px solid var(--line);border-radius:18px;background:white;overflow:hidden}.lab-layout{display:grid;grid-template-columns:minmax(0,1fr) 300px}.lab-stage{padding:22px;min-width:0}.lab-settings{padding:24px;background:#f8f9fc;border-left:1px solid var(--line);display:flex;flex-direction:column;gap:20px}.lab-settings label{display:block;font-size:15px;font-weight:700;margin-bottom:8px}.lab-settings select,.lab-settings input[type=number]{width:100%;min-height:46px;border:1px solid #9ba5b6;background:white;border-radius:7px;padding:9px;color:var(--ink)}.lab input[type=range]{width:100%;accent-color:var(--blue);min-height:32px;cursor:pointer}.lab fieldset{border:0;padding:0;margin:0}.lab legend{font-size:15px;font-weight:700;margin-bottom:8px}.segmented{display:flex;gap:7px;flex-wrap:wrap}.segmented button,.stage-buttons button{border:1px solid #aab2c0;border-radius:6px;background:white;color:var(--ink);min-height:44px;padding:8px 12px;font-size:14px}.segmented button[aria-pressed=true],.stage-buttons button[aria-pressed=true]{background:var(--ink);color:white;border-color:var(--ink)}.diagram{width:100%;display:block;min-height:230px;background:#fff;border:1px solid #e5e8ee;border-radius:10px}.diagram text{font-family:Arial,Helvetica,sans-serif;letter-spacing:0;fill:var(--ink)}.diagram-label{font-size:14px;color:var(--muted);margin-top:12px}.lab-status{min-height:82px;background:#eef1ff;border-left:4px solid var(--blue);padding:16px 18px;margin-top:18px;font-size:16px;line-height:1.5}.lab-status strong{display:block;color:var(--ink);margin-bottom:4px}.lab-metrics{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;margin-top:16px}.metric{background:var(--soft);border-radius:8px;padding:12px;min-width:0}.metric strong{font-size:23px;letter-spacing:-.035em;display:block;font-variant-numeric:tabular-nums}.metric span{font-size:13px;color:var(--muted);display:block}.lab-controls{display:flex;flex-wrap:wrap;gap:10px;align-items:center;padding:20px 22px;border-top:1px solid var(--line)}.lab-controls button{min-height:46px;min-width:80px;padding:9px 16px;border:1px solid #aab2c0;border-radius:7px;background:white;font-weight:700}.lab-controls button.primary{background:var(--blue);border-color:var(--blue);color:white}.lab-controls button:disabled{opacity:.5;cursor:default}.timeline{flex:1;min-width:160px}.timeline label{font-size:13px;display:flex;justify-content:space-between}.motion-option{font-size:14px;display:flex;align-items:center;gap:9px;padding:0 22px 18px}.motion-option input{width:18px;height:18px;accent-color:var(--blue)}.fixed-conditions{font-size:14px;padding:12px;background:#e7f6d4;border-radius:8px;line-height:1.5}.fixed-conditions strong{display:block}.lab-equation{font-size:18px;line-height:1.8;overflow-wrap:anywhere;text-align:center;padding:14px;border-radius:8px;background:#f3f5f9;margin-top:16px}.legend-row{display:flex;gap:14px;flex-wrap:wrap;font-size:14px;margin-top:12px}.legend-row span{display:flex;align-items:center;gap:6px}.legend-key{display:inline-block;width:13px;height:13px;border:2px solid var(--ink);border-radius:50%}.lesson-reading{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(0,1fr);gap:48px;padding:44px 0 60px}.lesson-reading h2{font-size:28px;margin-bottom:18px}.lesson-reading h3{font-size:20px;margin:25px 0 10px}.lesson-reading p,.lesson-reading li{font-size:16px;line-height:1.65}.lesson-reading ol{padding-left:25px}.lesson-reading li+li{margin-top:12px}.lesson-reading details{border:1px solid var(--line);border-radius:10px;padding:18px;margin-top:16px}.lesson-reading summary{font-weight:700;cursor:pointer}.lesson-reading details p{margin-top:14px}.book-reference{padding:25px;background:var(--soft);border-radius:12px;margin-top:22px}.book-reference p{margin:10px 0}.source-list{padding-left:20px;font-size:14px}.source-list a{overflow-wrap:anywhere}.library-banner{padding:22px;border-radius:12px;border:1px solid var(--line);background:white;margin:24px 0}.animation-card{display:flex;flex-direction:column;height:100%}.animation-card .mini-diagram{height:120px;display:flex;align-items:center;justify-content:center;background:#eef1ff;border-radius:8px;color:var(--blue);font-size:31px;font-weight:700;letter-spacing:-.03em;margin-bottom:20px}.animation-card .button{margin-top:24px;align-self:flex-start}.animation-card p{flex:1}.stage-buttons{display:flex;flex-wrap:wrap;gap:6px}.readout-note{font-size:14px;line-height:1.5;color:var(--muted)}.step-list .guide-name{font-size:13px;text-transform:uppercase;font-weight:700;letter-spacing:.04em;color:var(--blue);display:block;margin-bottom:5px}.lesson-next{margin-top:20px;padding-top:20px;border-top:1px solid var(--line)}.lesson-next a{display:block;margin-top:12px}.no-js-note{padding:20px;background:#fff6cf;margin:0;border-bottom:1px solid #d9c48a}.settings-extra label.check-label{display:flex;gap:8px;align-items:center;font-weight:400}.settings-extra input[type=checkbox]{width:18px;height:18px}.equation-spectator{text-decoration:line-through;color:#566579}.legend-symbol{font-weight:700}.lesson-reading .prose-note{color:var(--muted);margin-top:20px}.lab button:focus-visible{outline:3px solid #172468;outline-offset:3px}.lab-status:empty{display:none}
@media(max-width:900px){.lab-layout{grid-template-columns:1fr}.lab-settings{border-left:0;border-top:1px solid var(--line);display:grid;grid-template-columns:1fr 1fr}.fixed-conditions{grid-column:1/-1}.lesson-reading{gap:28px}.lab-stage{padding:18px}.diagram{min-height:0}}
@media(max-width:650px){.lesson-head{padding:24px 0 20px}.lesson-head h1{font-size:32px}.lab-section>.wrap{width:calc(100% - 20px)}.lab-stage{padding:12px}.lab-settings{padding:18px;gap:16px;grid-template-columns:1fr}.lab-controls{padding:16px 12px;gap:8px}.lab-controls button{min-width:70px;padding-inline:12px;font-size:15px}.timeline{flex-basis:100%;order:2}.lab-metrics{gap:6px}.metric{padding:9px}.metric strong{font-size:20px}.metric span{font-size:12px}.lab-status{padding:13px;font-size:16px;min-height:105px}.lab-equation{font-size:16px;text-align:left}.lesson-reading{grid-template-columns:1fr;padding-top:32px}.lesson-reading h2{font-size:26px}.motion-option{padding-inline:14px}.diagram-label{font-size:13px}.animation-card .mini-diagram{height:90px;font-size:27px}.lab-settings .fixed-conditions{font-size:14px}.lesson-head .lesson-meta{gap:7px}.lesson-meta .chip{font-size:12px}.lesson-reading .book-reference{padding:20px}}
@media(prefers-reduced-motion:reduce){.lab *{animation:none!important;transition:none!important}}
.diagram{max-height:380px}.lab-controls{border-top:0;border-bottom:1px solid var(--line)}.motion-option{padding-top:14px;border-bottom:1px solid var(--line);margin:0;padding-bottom:14px}.settings-extra>div+div{margin-top:20px}.metric strong{overflow-wrap:anywhere}.guide-name{font-size:13px;text-transform:uppercase;font-weight:700;letter-spacing:.04em;color:var(--blue);display:block;margin-bottom:5px}