:root{--bg:#faf8f2;--ink:#292d2b;--muted:#70756d;--gold:#a48343;--line:#e2dfd4;--panel:#202727;--soft:#f0ece1}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:35px}body{margin:0;background:var(--bg);color:var(--ink);font-family:Arial,"Nirmala UI",sans-serif;font-size:15px;line-height:1.65}button,input,select{font:inherit}button,a,input,select{outline-offset:5px}a{color:inherit;text-decoration:none}button{cursor:pointer}header{max-width:1440px;margin:auto;padding:28px 5%;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);gap:25px}.brand{display:flex;align-items:center;gap:12px;font-size:15px;letter-spacing:2px;font-weight:700}.brand 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/* Chapter 1 laboratories */
/* Shared interactive library */
.library-picker{display:grid;grid-template-columns:1fr 1fr;gap:24px;margin:0 0 14px}.library-picker label{font-size:11px;color:var(--muted)}.library-picker input[type=search]{width:100%;font-size:12px;padding:9px}.library-picker select{font-size:12px;padding:10px}.library-shortcuts{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:22px}.library-shortcuts button{font-size:11px}.sim-stage{padding:16px 10px 4px}.sim-stage .stage-top{padding:0 8px;gap:20px}.sim-stage svg{margin-top:12px;min-height:180px}.sim-presets{display:flex;flex-wrap:wrap;gap:8px;margin:15px 0}.sim-presets button{font-size:11px;padding:7px 10px}.sim-controls{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:20px 24px}.sim-controls label{min-width:0!important;font-size:11px;color:var(--ink)}.sim-controls output{float:none;display:block;color:var(--gold);font-variant-numeric:tabular-nums;margin-top:3px}.sim-controls input[type=range]{margin:10px 0;min-height:24px}.sim-transport{display:flex;gap:10px;align-items:center;background:var(--soft);padding:12px;margin:20px 0;border-radius:5px}.sim-transport button{font-size:11px;white-space:nowrap}.sim-transport label{flex:1;min-width:70px;font-size:11px}.sim-transport output{font-variant-numeric:tabular-nums}.sim-transport input{min-height:24px;margin-top:5px}.sim-readouts{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:16px}.sim-readouts strong{font-size:19px;overflow-wrap:anywhere;font-variant-numeric:tabular-nums}.sim-readouts small{font-size:9px;letter-spacing:.7px}.sim-formula{background:var(--soft);padding:12px 15px;border-left:2px solid var(--gold);font-size:12px!important;overflow-wrap:anywhere}.sim-error:empty{display:none}.sim-assumptions{line-height:1.8}.lesson-list{align-self:start}.lesson-list .lesson{font-size:12px}.lesson-list .lesson small{font-size:10px}#lab-search-status:empty{display:none}.lab-navigation{display:flex;justify-content:space-between;gap:12px;margin:24px 0 0}.lab-navigation button{font-size:11px}.lab-navigation button:disabled{opacity:.4;cursor:default}#practical-list a{color:var(--gold)}
@media(min-width:1100px){.workspace{grid-template-columns:205px minmax(0,1fr) 190px}.lesson-main{padding:25px 22px}}
@media(max-width:700px){.library-picker{grid-template-columns:1fr;gap:12px}.library-shortcuts{gap:6px}.library-shortcuts button{padding:7px 8px;font-size:10px}.sim-stage{margin:0 -6px;padding:12px 2px 4px}.sim-stage .stage-top{font-size:7px;letter-spacing:1px}.sim-stage svg{min-height:155px}.sim-controls{gap:16px}.sim-controls label{font-size:11px}.sim-transport{flex-wrap:wrap}.sim-transport label{flex-basis:100%}.sim-readouts strong{font-size:18px}.sim-presets button{font-size:10px}.sim-readouts small{font-size:8px}.lesson-list .lesson{width:100%;min-height:44px}#lab-list{max-height:250px;overflow:auto}.lesson-list .aside-note{display:none}.sim-assumptions{font-size:12px!important}}
#sig-count{color:#c7c9b9}
.sim-mobile-hint{display:none}.sim-stage{overscroll-behavior-x:contain}
@media(max-width:700px){.sim-stage{overflow-x:auto!important}.sim-stage svg{min-width:680px}.sim-mobile-hint{display:block;margin:7px 0 12px;font-size:10px!important;color:var(--muted)}}
.full-control{display:block;font-size:11px;margin:20px 0;color:var(--muted)}
.full-control input,.controls input[type=text],.controls input[type=number]{width:100%;min-width:0;display:block;padding:8px;border:1px solid var(--line);border-radius:4px;background:var(--bg);margin-top:6px}
.base-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin:20px 0}.base-grid label{font-size:10px}.base-grid small{display:block;font-size:9px;color:var(--muted)}
.conversion-equation{display:flex;justify-content:center;align-items:center;gap:25px;padding:34px 0 18px;color:#e7cd94;font:24px Georgia,serif;flex-wrap:wrap}.conversion-equation strong{font-weight:400;overflow-wrap:anywhere}
#conversion-factor{color:#c3c4b5;text-align:center;font-size:12px}.new-lab .controls{flex-wrap:wrap}.new-lab .controls label{min-width:90px}.new-lab .equation{overflow-wrap:anywhere}
.input-error{color:#a14c37;font-size:12px}.lesson-support{border-top:1px solid var(--line);padding-top:12px;margin-top:20px}.lesson-support details{padding:9px 0}.lesson-support summary{cursor:pointer;color:var(--gold);font-size:12px}.lesson-support p{padding-top:10px}.chart-legend{font-size:10px!important;color:#c7c9b9;text-align:center}
@media(max-width:700px){.base-grid{grid-template-columns:repeat(2,minmax(0,1fr))}.lesson-list .lesson{width:100%;display:block;margin:4px 0}.lesson-list .lesson small{display:inline;margin-left:8px;padding:0}.new-lab .controls label{min-width:40%}.new-lab .readouts{flex-wrap:wrap}.new-lab .readouts>div{min-width:40%}}