:root{--ink:#1b3435;--muted:#637579;--green:#176c62;--line:#dce4e3;--bg:#f4f7f5;--warm:#e9ad4e;--blue:#386ba6}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:Inter,Arial,sans-serif}button,input{font:inherit}button{border:0;border-radius:8px;background:var(--green);color:white;padding:13px 19px;font-size:13px;font-weight:700;cursor:pointer;transition:background .15s,transform .15s}button:hover{filter:brightness(.94)}button:active{transform:translateY(1px)}button:disabled{opacity:.4;cursor:default}button:focus-visible,input:focus-visible,summary:focus-visible,canvas:focus-visible{outline:3px solid var(--warm);outline-offset:4px}a{color:var(--green)}header{max-width:1500px;margin:auto;padding:25px 4%;display:flex;justify-content:space-between;align-items:center;gap:25px;border-bottom:1px solid var(--line)}.brand{display:flex;align-items:center;gap:12px;color:var(--ink);text-decoration:none;font-size:10px;letter-spacing:2px;line-height:1.5}.brand b{font-size:15px;letter-spacing:3px}.brandmark{display:block;font-size:24px;letter-spacing:0;border:1px solid var(--green);border-radius:5px;padding:7px 9px;font-weight:bold;position:relative}.brandmark>span{font-size:12px}.author{font-size:12px;font-weight:600;text-align:right}main{max-width:1500px;margin:auto;padding:0 4%}.intro{display:flex;justify-content:space-between;align-items:center;gap:20px;padding:40px 0 28px}.eyebrow{font-size:10px;letter-spacing:1.8px;font-weight:700;color:var(--green)}h1{font-size:clamp(30px,3.3vw,47px);line-height:1.18;letter-spacing:-1.6px;font-weight:650;margin:13px 0}h1 em{font-style:normal;color:var(--green)}.intro p,.catalog p,.sectionheading p{font-size:14px;line-height:1.7;color:var(--muted);margin:8px 0}.introformula{display:flex;align-items:center;gap:10px;font:27px Georgia,serif;padding:20px 35px;white-space:nowrap}.introformula b{position:relative;font-weight:400}.introformula sup,.introformula sub{position:absolute;left:2px;font-size:24px;letter-spacing:2px}.introformula sup{top:-24px}.introformula sub{bottom:-24px}.introformula i{font-style:normal;color:var(--green)}.search{background:white;border:1px solid var(--line);border-radius:12px;display:grid;grid-template-columns:1fr .9fr;gap:40px;padding:25px;margin-bottom:28px;align-items:center}label{display:block;font-weight:700;font-size:13px;margin-bottom:10px}.inputrow{display:flex;gap:9px}.inputrow input{min-width:0;width:100%;border:1px solid #a9c1bd;border-radius:7px;background:#f9fcfb;color:var(--ink);font-size:22px;padding:12px 15px}.inputrow button{white-space:nowrap}small{display:block;color:var(--muted);font-size:11px;line-height:1.6;margin-top:8px}.examples{display:flex;flex-wrap:wrap;gap:7px;margin:10px 0}.chip{padding:9px 13px;background:#f1f6f4;color:var(--green);border:1px solid #d9e5e0;font-size:14px}#error{color:#a43e25;margin:8px 0 0;font-size:13px;line-height:1.5}#error:empty{display:none}#studyStatus{font-size:12px;color:var(--green);margin:8px 0 0;min-height:16px}.activity{scroll-margin-top:16px}.sessionhead{display:flex;justify-content:space-between;align-items:center;padding:10px 0 20px;gap:15px}.moleculetitle{display:flex;align-items:baseline;gap:13px;margin-top:7px}#badge{font-size:34px;font-weight:650;letter-spacing:-1px}#badge sub{font-size:20px}#badge sup{font-size:17px}#moleculeName{font-size:14px;color:var(--muted)}.secondary{background:#e9efed;color:var(--ink)}.phases{display:grid;grid-template-columns:repeat(4,1fr);gap:10px;margin:0 0 13px}.phase{border:1px solid var(--line);border-radius:8px;padding:12px 14px;display:flex;gap:10px;align-items:center;color:#7a8889;font-size:12px;background:#eff3f1}.phase b{font-size:12px;border:1px solid #cbd7d3;border-radius:50%;width:25px;height:25px;display:grid;place-items:center;flex-shrink:0}.phase.active{background:#e2f1eb;border-color:#90b8a9;color:var(--green)}.phase.active b{background:var(--green);border-color:var(--green);color:white}.phase.done{color:var(--green)}.progressTrack{height:3px;background:#e0e7e2;border-radius:4px;overflow:hidden;margin-bottom:23px}.progressTrack>div{height:100%;background:var(--green);transition:width .3s}.workspace{display:grid;grid-template-columns:165px minmax(300px,.9fr) minmax(360px,1.1fr);gap:20px;align-items:start}aside{padding-top:16px}nav{margin-top:15px;max-height:620px;overflow:auto}nav button{display:flex;align-items:center;text-align:left;gap:9px;padding:9px 6px;border-radius:5px;width:100%;margin-bottom:4px;background:none;color:var(--muted);font-weight:500;font-size:11px;line-height:1.4}nav button i{font-style:normal;font-size:10px;display:grid;place-items:center;border:1px solid #ccd7d3;border-radius:50%;width:22px;height:22px;flex-shrink:0}nav button.active{background:#e0eee7;color:var(--green);font-weight:700}nav button.active i{background:var(--green);color:white;border-color:var(--green)}nav button:disabled{opacity:.42}.asideNote{border-top:1px solid var(--line);padding:16px 5px;margin-top:15px;font-size:11px;color:var(--muted);line-height:1.6}.asideNote b{display:block;font-weight:500;margin-top:5px}.lesson,.visual{background:white;border:1px solid var(--line);border-radius:12px;min-height:590px;padding:25px}.lessonhead{display:flex;justify-content:space-between;gap:8px;align-items:center;font-size:10px;font-weight:700;letter-spacing:.6px;color:var(--muted)}#phaseLabel{color:var(--green)}h2{font-size:25px;line-height:1.25;letter-spacing:-.7px;font-weight:650;margin:17px 0 12px}.objective{font-size:13px;font-weight:500;line-height:1.6;color:var(--muted);padding-bottom:15px;border-bottom:1px solid var(--line)}#content{font-size:14px;line-height:1.75;color:#425a5d}#content p{margin:14px 0}#content b{color:var(--ink)}.calc{background:#edf5f0;border-left:3px solid #76aa94;border-radius:0 6px 6px 0;padding:15px;margin:16px 0;color:var(--ink);font-size:17px;font-weight:650;line-height:1.6}.row{display:flex;justify-content:space-between;align-items:center;padding:9px 0;border-bottom:1px solid #edf1ef;gap:15px}.row b{text-align:right}.learningCue{display:none}.visualtop{display:flex;justify-content:space-between;align-items:center;gap:15px}#viewBadge{font-size:10px;letter-spacing:1px;background:#f0f4f2;padding:5px 8px;border-radius:4px;color:var(--muted)}.viewtabs{display:flex;gap:4px;background:#f1f5f3;padding:4px;border-radius:7px;margin-top:16px}.viewtabs button{flex:1;background:none;color:var(--green);padding:9px;font-size:11px}.viewtabs button.selected{background:white;box-shadow:0 1px 5px #1b343515}#drawing{min-height:340px;display:grid;place-items:center;padding:12px 0}#drawing svg{height:340px;width:100%}svg{width:100%}#stageText,#caption{font-size:11px;color:var(--muted);line-height:1.6;margin:6px 0;text-align:center}#stageText{font-weight:600;color:var(--green)}#facts{margin-top:15px;border-top:1px solid var(--line);display:flex;justify-content:space-around;gap:10px;padding-top:16px;color:var(--muted);text-align:center;font-size:10px}#facts b{display:block;color:var(--ink);font-size:20px;margin-bottom:4px}.worknav{grid-column:2 / 4;display:flex;align-items:center;justify-content:space-between;gap:12px;background:white;border:1px solid var(--line);border-radius:10px;padding:15px 20px;margin-top:-5px;position:sticky;bottom:12px;z-index:5;box-shadow:0 5px 18px #1b343509}#nextHint{font-size:11px;color:var(--muted);text-align:center;line-height:1.5}#next{min-width:142px}.switch{display:flex;justify-content:center;align-items:center;gap:8px;margin:12px 0;font-size:11px;font-weight:500}.switch input{accent-color:var(--green)}#threeControls{text-align:center}#threeControls button{font-size:11px;padding:8px 12px}canvas{display:block;width:100%;height:340px;touch-action:none;cursor:grab}canvas:active{cursor:grabbing}.advanced{margin:36px 0;display:grid;gap:12px}.sectionheading h2{margin-bottom:8px}.sectionheading{margin-bottom:5px}details{border:1px solid var(--line);background:white;border-radius:9px;overflow:hidden}summary{cursor:pointer;padding:21px 24px;display:flex;gap:16px;font-size:12px;font-weight:700;color:var(--green);align-items:center}summary span{font-size:15px;color:var(--ink);flex:1}summary i{font-size:19px;font-style:normal}details[open]>summary{border-bottom:1px solid var(--line)}details[open]>summary i{transform:rotate(45deg)}details>div{padding:20px 25px;font-size:14px;line-height:1.7;color:#425a5d}h3{font-size:17px}.envalues{display:flex;gap:12px;flex-wrap:wrap;margin:15px 0}.envalues>div{padding:15px 22px;border-radius:6px;background:#eef5f0;display:flex;flex-direction:column}.envalues b{font-size:24px;color:var(--green)}.tablewrap{overflow:auto}table{width:100%;border-collapse:collapse;text-align:left;font-size:13px}th,td{padding:12px;border-bottom:1px solid var(--line)}th{background:#f1f5f3}.resgrid{display:grid;grid-template-columns:repeat(auto-fit,minmax(220px,1fr));gap:13px;margin:20px 0}.rescard{background:#f7f9f7;color:var(--ink);border:2px solid transparent;white-space:normal;text-align:left;padding:18px;font-weight:400;line-height:1.6}.rescard.selected{border-color:var(--green);background:#eef5ef}.rescard b,.rescard span,.rescard strong{display:block;font-size:12px}.rescard svg{height:170px}.catalog{padding:5px 0 35px}#catalog{display:flex;gap:8px;flex-wrap:wrap;margin-top:18px}footer{display:flex;justify-content:space-between;gap:15px;border-top:1px solid var(--line);padding:25px 0;font-size:10px;color:var(--muted)}
/* Atomic configuration learning cards */
.atomOverview{display:flex;align-items:center;gap:19px;margin:18px 0}.periodicTile{border:2px solid var(--green);border-radius:6px;width:105px;height:118px;flex-shrink:0;padding:8px 10px;position:relative;background:#f4faf6}.atomicZ{font-size:19px;font-weight:700;color:var(--green);display:block}.atomSymbol{font-size:43px;font-weight:600;display:block;line-height:1.15;text-align:center}.atomName{font-size:10px;display:block;text-align:center;margin-top:3px}.atomicNumbers{display:grid;gap:9px;font-size:12px}.atomicNumbers b{font-size:24px;margin-right:5px}.atomicNumbers small{margin:0}.configReading{border:1px solid var(--line);border-radius:6px;padding:13px 15px;background:#fafcfb;margin:16px 0}.configReading .configLine{font-size:22px;line-height:1.7;letter-spacing:.5px}.sublevel{display:inline-block;margin-right:7px;white-space:nowrap}.sublevel sup{font-size:.7em}.valenceSub{background:#fff0cb;color:#7b561b;border-radius:3px;padding:1px 4px}.valenceBand{display:flex;justify-content:space-between;align-items:center;background:#fff6df;border:1px solid #eed6a3;border-radius:6px;padding:15px;margin-top:14px;gap:12px}.valenceBand strong{font-size:34px;color:#855d22}.valenceBand span{font-size:12px;line-height:1.6}.configVisual{width:100%;align-self:start;padding-top:8px}.visualZ{display:flex;align-items:center;justify-content:center;gap:14px;font-size:13px;margin:16px 0}.visualZ b{font-size:32px;color:var(--green)}.configVisual h3{text-align:center;font-size:13px;font-weight:600;margin:22px 0 10px}.configVisual .configLine{font-size:20px;line-height:1.9;text-align:center;padding:12px}.orbitalGroup{display:flex;align-items:center;justify-content:center;gap:14px;flex-wrap:wrap;margin:15px 0}.orbital{display:flex;flex-direction:column;align-items:center;gap:8px}.orbitalLabel{font-size:12px;font-weight:600}.boxes{display:flex;gap:4px}.orbitalBox{width:38px;height:40px;border:1.5px solid #6c9083;border-radius:3px;display:flex;justify-content:center;align-items:center;color:var(--ink);font:22px Georgia,serif;letter-spacing:1px;background:#f8fbf9}.orbitalNote{text-align:center;font-size:12px;background:#f2f6f3;padding:12px;border-radius:6px;line-height:1.6}.orbitalNote b{color:var(--green)}.budgetVisual{width:100%;text-align:center}.budgetTotal{font-size:62px;color:var(--green);font-weight:600;line-height:1.1;margin:20px 0 0}.budgetVisual h3{font-size:14px;font-weight:500}.electronBank{display:flex;justify-content:center;flex-wrap:wrap;gap:7px;max-width:360px;margin:22px auto}.electronPair{display:flex;gap:4px;border:1px solid #d2dfd8;border-radius:5px;background:#f4faf6;padding:9px}.electronPair i{background:#2b6653;border-radius:50%;width:6px;height:6px}.calcTable{font-size:13px}.calcTable .row>span:first-child{flex:1}.calcTable .row b{min-width:30px}.newatom,.newbond,.electron{animation:fadeIn .4s ease-out both}.changeAtom{fill:#176c62}.changeBond{stroke:#bd7b24;animation:inkIn 1s ease-out}.changeElectron{fill:#bd7b24;animation:dotIn 1s ease-out}.focusHint{font-size:11px;color:#855d22;text-align:center}.electronAccounting{font-size:12px;text-align:center;padding-top:10px;border-top:1px solid var(--line)}@keyframes fadeIn{from{opacity:0}to{opacity:1}}@keyframes inkIn{from{stroke:#e5a23c;stroke-width:5}to{stroke:#172322;stroke-width:2.2}}@keyframes dotIn{from{fill:#e5a23c;r:4}to{fill:#172322;r:2.8}}@media(prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
@media(max-width:1150px){.workspace{grid-template-columns:140px minmax(280px,.95fr) minmax(310px,1fr);gap:13px}.lesson,.visual{padding:20px}main{padding:0 3%}.author{font-size:11px}.introformula{padding-right:10px}h2{font-size:23px}}@media(max-width:950px){.workspace{grid-template-columns:1fr 1fr}aside{display:none}.worknav{grid-column:1/3}.search{gap:22px}.introformula{display:none}.phase{font-size:11px;padding:11px}.lesson,.visual{min-height:610px}.atomOverview{gap:12px}.periodicTile{width:90px}.atomicNumbers b{font-size:21px}}@media(max-width:650px){header{padding:20px 5%;flex-wrap:wrap;gap:14px}.author{text-align:left;width:100%;font-size:11px}main{padding:0 5%}.intro{padding:28px 0 20px}h1{font-size:32px;letter-spacing:-1px}.search{grid-template-columns:1fr;padding:20px;gap:18px}.search>div .eyebrow{display:none}.search>div small{display:none}.inputrow input{font-size:20px}.workspace{display:flex;flex-direction:column;gap:14px}.lesson,.visual{width:100%;min-height:0;padding:22px}.visual{min-height:480px}#drawing{min-height:300px}#drawing svg,canvas{height:300px}.worknav{width:100%;padding:13px;bottom:8px;margin-top:0}#nextHint{display:none}#next{min-width:135px}.phases{gap:5px}.phase{flex-direction:column;gap:6px;text-align:center;font-size:9px;padding:9px 5px}.phase b{width:22px;height:22px;font-size:10px}.moleculetitle{gap:10px}#moleculeName{font-size:12px}.sessionhead button{font-size:11px;padding:10px}summary{padding:19px 17px}summary span{font-size:13px}details>div{padding:18px}.intro p{font-size:13px}footer span{display:none}footer{line-height:1.6}.configVisual .configLine{font-size:19px}.valenceBand strong{font-size:30px}}
[hidden]{display:none!important}.changeBond{stroke:#172322}.changeElectron{fill:#172322}.phase.done b{background:#eef6f0}
#drawing .modelStage{position:relative;width:100%;height:420px;overflow:hidden;border-radius:10px;border:1px solid #e1e8ec;background:#f2f6f8}.modelStage canvas{position:absolute;inset:0;width:100%;height:100%;border-radius:10px}.modelStage #modelLabels{pointer-events:none}.modelTag{position:absolute;top:13px;left:14px;font-size:8px;letter-spacing:1.4px;font-weight:700;color:#718794;pointer-events:none}.modelLegend{display:flex;flex-wrap:wrap;justify-content:center;gap:12px;padding:15px 5px 0;width:100%}.modelLegend span{font-size:11px;display:flex;align-items:center;gap:5px;color:#53666c}.modelLegend i{width:11px;height:11px;border-radius:50%;border:1px solid #c0cdd1}.modelLegend small{flex-basis:100%;text-align:center;margin-top:0}.visual.expanded{position:fixed;inset:3vh 4vw;z-index:1000;max-width:1150px;margin:auto;overflow:auto;box-shadow:0 0 0 100vmax #152c37aa;padding:25px;min-height:0}.visual.expanded #drawing .modelStage{height:calc(82vh - 210px);min-height:320px}.visual.expanded #facts{display:none}#drawing:has(.modelStage){display:flex;flex-direction:column}#threeControls button{margin:3px}.visual.expanded .viewtabs{display:none}@media(max-width:650px){#drawing .modelStage{height:360px}.visual.expanded{inset:2vh 3vw;padding:16px}.visual.expanded #drawing .modelStage{height:calc(82vh - 230px);min-height:280px}}
/* Compact, continuous learning surface. */
header{padding-top:14px;padding-bottom:14px}.intro{padding:18px 0 13px;gap:12px}.intro h1{font-size:30px;margin:7px 0;letter-spacing:-1px}.intro p{font-size:12px;margin:4px 0}.introformula{font-size:21px;padding:10px 20px}.introformula sup,.introformula sub{font-size:18px}.search{padding:15px 18px;gap:25px;margin-bottom:14px;border-radius:9px}.inputrow input{font-size:19px;padding:9px 12px}.inputrow button{padding:10px 15px}.search label{font-size:12px;margin-bottom:7px}.search small{font-size:10px;margin-top:5px}.search .chip{padding:6px 11px;font-size:12px}.examples{margin:7px 0}.sessionhead{padding:5px 0 12px}.moleculetitle{margin-top:4px}#badge{font-size:28px}#moleculeName{font-size:12px}.sessionhead button{padding:9px 12px;font-size:11px}.phases{gap:5px;margin-bottom:8px}.phase{padding:8px 12px;font-size:11px;gap:8px;border-radius:5px}.phase b{height:21px;width:21px;font-size:10px}.progressTrack{margin-bottom:9px}.workspace{grid-template-columns:minmax(285px,.9fr) minmax(340px,1.1fr);gap:0;align-items:stretch;background:#fff;border:1px solid var(--line);border-radius:0 0 9px 9px;overflow:clip}.workspace aside{display:none}.lesson,.visual{border:0;border-radius:0;min-height:0;padding:17px 20px}.lesson{border-right:1px solid var(--line)}.lessonhead{font-size:9px}h2{font-size:22px;margin:11px 0 8px;letter-spacing:-.4px}.objective{font-size:12px;line-height:1.45;margin:7px 0 10px;padding-bottom:9px}#content{font-size:13px;line-height:1.55}#content p{margin:10px 0}.calc{font-size:16px;line-height:1.5;padding:10px 12px;margin:11px 0}.row{padding:6px 0}.visualtop .eyebrow{font-size:9px}.viewtabs{margin-top:8px;padding:3px}.viewtabs button{padding:6px;font-size:10px}#drawing{min-height:250px;padding:4px 0}#drawing svg{height:255px}#caption,#stageText{font-size:10px;line-height:1.45;margin:4px 0}#facts{padding-top:9px;margin-top:9px;font-size:9px}#facts b{font-size:17px;margin-bottom:2px}.worknav{grid-column:1/3;margin:0;border:0;border-top:1px solid var(--line);border-radius:0;padding:11px 16px;box-shadow:none;bottom:0;position:relative;background:#f8fbf9}#nextHint{font-size:10px}.worknav button{padding:10px 16px;font-size:12px}.atomOverview{gap:16px;margin:11px 0}.periodicTile{width:83px;height:98px;padding:6px 8px}.atomicZ{font-size:18px}.atomSymbol{font-size:35px}.atomName{font-size:9px}.atomicNumbers{gap:6px;font-size:11px}.atomicNumbers b{font-size:21px}.configReading{padding:9px 12px;margin:10px 0}.configReading .configLine{font-size:20px;line-height:1.6}.valenceBand{padding:10px 12px;margin-top:9px}.valenceBand strong{font-size:27px}.valenceBand span{font-size:11px}.configVisual{padding-top:0}.visualZ{margin:9px 0;font-size:12px;gap:16px}.visualZ b{font-size:26px}.configVisual h3{font-size:12px;margin:12px 0 5px}.configVisual .configLine{font-size:19px;line-height:1.6;padding:7px}.orbitalGroup{margin:10px 0;gap:12px}.orbital{gap:5px}.orbitalBox{width:33px;height:34px;font-size:20px}.orbitalNote{font-size:11px;line-height:1.5;padding:9px}.budgetTotal{font-size:48px;margin:10px 0 0}.electronBank{gap:5px;margin:14px auto}.electronPair{padding:7px;gap:3px}.budgetVisual h3{font-size:12px}.advanced{margin:23px 0;gap:9px}.sectionheading h2{font-size:20px;margin:8px 0 5px}.sectionheading p,.catalog p{font-size:12px;margin:4px 0}summary{padding:15px 19px}summary span{font-size:13px}.catalog{padding:0 0 22px}.catalog h2{font-size:20px;margin:8px 0}#catalog{gap:6px;margin-top:12px}#catalog .chip{font-size:12px;padding:7px 11px}footer{padding:17px 0}#drawing .modelStage{height:310px}.modelLegend{gap:9px;padding-top:9px}.modelLegend span{font-size:10px}.modelLegend small{font-size:9px}#threeControls button{font-size:10px;padding:7px 9px}.switch{font-size:10px;margin:9px 0}.continuity{display:flex;align-items:stretch;gap:9px;padding:9px 12px;background:#ebf1ed;border:1px solid var(--line);border-bottom:0;border-radius:8px 8px 0 0;overflow-x:auto}.snapshot{display:flex;align-items:center;text-align:left;flex:1;min-width:0;gap:10px;background:#f5f8f6;color:var(--ink);border:1px solid #d5e1da;border-radius:6px;padding:5px 9px;font-weight:400;cursor:pointer}.snapshot.current{border:1.5px solid var(--green);background:#fff;box-shadow:0 1px 4px #173f3b0a}.snapshot.upcoming{opacity:.55}.snapshotFigure{flex:0 0 69px;height:59px;display:flex;align-items:center;justify-content:center}.snapshotFigure svg{width:69px;height:59px}.snapshotText{min-width:0;display:block}.snapshotText small{font-size:8px;letter-spacing:.5px;color:var(--green);margin:0 0 4px;line-height:1.4}.snapshotText b{display:block;font-size:11px;font-weight:600;line-height:1.4}.flowArrow{align-self:center;color:#729384;font-size:21px;flex-shrink:0}.miniAtom{display:grid;grid-template-columns:auto auto;align-items:center;gap:2px 4px}.miniAtom sup{font-size:8px}.miniAtom>b{font-size:25px}.miniAtom>span{font-size:7px;grid-column:1/3;text-align:center}.miniBudget{display:flex;flex-direction:column;align-items:center}.miniBudget b{font-size:19px;color:var(--green)}.miniBudget span{font-size:8px}.miniSpace{font-size:11px;display:flex;gap:2px;align-items:center;color:var(--green)}.miniSpace span,.miniSpace i{font-size:21px;font-style:normal}.pendingStep{display:grid;place-items:center;border:1px dashed #b7c9be;width:30px;height:30px;border-radius:50%;color:#8c9f92;font-size:15px}.visual.expanded #drawing .modelStage{height:calc(82vh - 210px)}
@media(max-width:950px){.lesson,.visual{min-height:0}.workspace{grid-template-columns:1fr 1fr}.snapshotFigure{flex-basis:55px}.snapshotFigure svg{width:55px}.snapshot{gap:7px;padding:5px 7px}.snapshotText b{font-size:10px}}@media(max-width:650px){header{padding:12px 5%;gap:8px}.brandmark{font-size:19px;padding:5px 7px}.brand b{font-size:12px}.author{font-size:10px}.intro{padding:15px 0 10px}.intro h1{font-size:25px;line-height:1.2}.intro p{font-size:11px}.intro .eyebrow{font-size:8px}.search{padding:12px 14px;gap:9px}.search small{font-size:9px}.search .examples{margin:3px 0;gap:5px}.search .chip{padding:5px 8px}.search>div .eyebrow{display:none}.phase{flex-direction:row;justify-content:center;gap:4px;padding:7px 3px;font-size:8px}.phase b{width:17px;height:17px;font-size:8px}.workspace{display:flex;flex-direction:column;overflow:clip}.lesson,.visual{padding:14px 16px}.lesson{border-right:0;border-bottom:1px solid var(--line)}.objective{font-size:11px;margin-bottom:7px}#content{font-size:12px}#content p{margin:8px 0}.worknav{position:sticky;padding:10px 12px;margin-top:0}.visual{min-height:0}#drawing{min-height:210px}#drawing svg{height:230px}.continuity{gap:5px;padding:7px 8px}.snapshot{flex:0 0 142px;gap:4px;padding:4px 6px}.snapshotFigure{flex-basis:45px;height:51px}.snapshotFigure svg{width:45px;height:51px}.snapshotText small{font-size:7px}.snapshotText b{font-size:9px}.flowArrow{font-size:16px}.snapshotFigure .miniAtom b{font-size:21px}#drawing .modelStage{height:290px}.visual.expanded #drawing .modelStage{height:calc(82vh - 230px)}.visual.expanded .modelLegend{display:none}.atomOverview{margin:8px 0}.configReading .configLine{font-size:18px}.valenceBand strong{font-size:25px}.advanced{margin-top:18px}.sessionhead .eyebrow{font-size:8px}#badge{font-size:24px}#moleculeName{font-size:11px}}
.atomicNumbers>b{font-size:13px;margin:0}.atomicNumbers>span{font-size:12px}.atomicNumbers small{font-size:11px;max-width:240px}.periodicTile .atomicZ{font-size:16px;white-space:nowrap}.configVisual h3{margin-top:8px}.configVisual .orbitalGroup{margin:18px 0}.configVisual .valenceBand{margin-top:15px}.miniAtom{display:flex;justify-content:center;align-items:center}.miniAtom>b{font-size:28px}#stageText:empty{display:none}
.atomicSymbols{display:flex;justify-content:center;align-items:center;gap:12px 18px;flex-wrap:wrap;width:100%;max-width:520px;margin:0 auto}.atomLewis{margin:0;flex:0 0 86px;text-align:center}#drawing .atomLewis svg{width:86px;height:88px;display:block}.atomLewis figcaption{font-size:10px;color:var(--muted);line-height:1.4;margin-top:3px}#drawing:has(.atomicSymbols){display:block;min-height:140px;padding:18px 0 10px}@media(max-width:650px){.atomicSymbols{gap:9px 12px}.atomLewis{flex-basis:76px}#drawing .atomLewis svg{width:76px;height:80px}#drawing:has(.atomicSymbols){min-height:110px;padding:12px 0 7px}}
.objective.stepAction{background:#fff1cf;border:1px solid #e2ba64;border-left:5px solid #ba802a;border-radius:5px;padding:12px 14px;color:#5a4218;font-size:14px;font-weight:700;line-height:1.55;margin:12px 0}.stepAction:before{content:'QUÈ HAS DE FER ARA';display:block;font-size:9px;letter-spacing:1.3px;color:#8b6327;margin-bottom:5px}#nextHint{font-size:12px;font-weight:650;color:var(--green);max-width:440px}.countStep .lesson{border-right:0}.countStep #content{max-width:720px}.countStep .lessonhead{max-width:720px}.countStep .stepAction{max-width:720px}#consultFormal{margin:8px 0}@media(max-width:650px){.objective.stepAction{font-size:12px;padding:10px 12px}#nextHint{display:block;flex:1;font-size:10px;line-height:1.4;max-width:155px}.worknav{gap:8px}.worknav button{padding:10px 12px}#next{min-width:98px}.countStep #content{max-width:none}}
.inputrow select{min-width:0;width:100%;background:#f9fcfb;border:1px solid #a9c1bd;border-radius:7px;color:var(--ink);font:600 15px Arial,sans-serif;padding:11px 10px;cursor:pointer}.inputrow select:focus-visible{outline:3px solid var(--warm);outline-offset:3px}.manualFormula{margin-top:8px;background:none;border:0;border-radius:0;overflow:visible}.manualFormula>summary{display:list-item;padding:3px 0;color:var(--muted);font-size:10px;font-weight:500}.manualFormula[open]>summary{border:0}.manualFormula>label{font-size:10px;margin:8px 0 5px}.manualFormula>input{border:1px solid #a9c1bd;background:#fff;border-radius:5px;padding:8px 10px;width:100%;font-size:14px;color:var(--ink)}.manualFormula>small{margin:3px 0}@media(max-width:650px){.inputrow select{font-size:13px;padding:10px 8px}}
.phases button.phase{font-weight:500;cursor:pointer;text-align:left}.phases button.phase:disabled{cursor:not-allowed;opacity:.48}.phases button.phase.active{opacity:1}.countStep .worknav{grid-column:1 / -1}body:has(#advancedPanel[hidden]) .workspace{margin-bottom:24px}.phase:disabled:hover{filter:none}@media(max-width:650px){.phases button.phase{font-size:8px;line-height:1.4;text-align:center}.worknav #next{min-width:115px}}

.modelInteraction{flex:1 0 100%;display:flex;flex-wrap:wrap;gap:4px 12px;padding:10px 12px;background:#e8f3ef;border:1px solid #a4c8bb;border-left:4px solid var(--green);border-radius:7px;font-size:12px;line-height:1.5;color:var(--ink)}.modelInteraction strong{flex-basis:100%;color:var(--green);font-size:13px}.modelInteraction span:last-child{font-size:11px}#moleculeCanvas{cursor:grab;touch-action:none}#moleculeCanvas:active{cursor:grabbing}

#drawing{position:relative}.modelLoading{min-height:280px;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:12px;color:var(--green);background:#f4f8f6;text-align:center;padding:24px}.modelLoading[hidden]{display:none}#drawing:has(.modelStage)>.modelLoading{position:absolute;inset:0;z-index:3}.modelLoading>span:last-child{font-size:12px;color:var(--muted)}.loadingSpinner{width:32px;height:32px;border:3px solid #d2e6de;border-top-color:var(--green);border-radius:50%;animation:modelSpin .8s linear infinite}@keyframes modelSpin{to{transform:rotate(360deg)}}@media(prefers-reduced-motion:reduce){.loadingSpinner{animation:none}}

.resonanceOverview{padding:20px}.resonanceSequence{display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:8px}.resonanceOverview figure{margin:0;flex:1 1 140px;max-width:230px;text-align:center}.resonanceOverview svg{width:100%;max-height:200px;background:white}.resArrow{font-size:30px;color:#17685b}.hyperModel{display:flex;align-items:center;gap:24px}.hyperModel p{flex:1}.hyperModel figure{min-width:150px}.resonanceOverview figcaption{font-size:14px;font-weight:600}@media(max-width:600px){.hyperModel{flex-direction:column}.resonanceSequence{gap:2px}.resonanceSequence figure{flex-basis:70px}.resArrow{font-size:22px}}

.modelNotice{padding:12px 15px;border-left:4px solid #b37a20;background:#fff6df;border-radius:8px;margin:12px 0}.modelNotice p:last-child{margin-bottom:0}#content .resonanceSequence figure{flex:1 1 90px;margin:0;max-width:170px;text-align:center}#content .resonanceSequence svg{width:100%;max-height:150px}

.dipoleEquation{display:flex;flex-wrap:wrap;align-items:center;gap:10px;padding:10px 14px;font-size:1rem;line-height:1.3}.dipoleEquation img{display:block;flex:0 1 auto;width:210px;max-width:100%;height:auto;max-height:64px;object-fit:contain}.dipoleEquation strong{white-space:nowrap;font-size:1rem}

header .authorContact{display:flex;align-items:center;gap:18px;max-width:100%}header .author{display:block;font-size:clamp(14px,1.3vw,17px);font-weight:750;line-height:1.5;color:var(--ink);text-align:right}.contactButton{display:inline-flex;align-items:center;justify-content:center;background:#176c62;color:white!important;text-decoration:none;padding:11px 18px;border-radius:8px;font-size:14px;font-weight:700;white-space:nowrap;min-height:42px}.contactButton:hover{background:#10564e}.contactButton:focus-visible{outline:3px solid #e9ad4e;outline-offset:3px}@media(max-width:800px){header{flex-wrap:wrap;gap:14px}header .authorContact{width:100%;justify-content:space-between;gap:12px}header .author{text-align:left;width:auto;font-size:14px}.contactButton{padding:10px 14px}}

.languageSelector a{display:inline-flex;align-items:center;gap:6px;text-decoration:none;padding:5px 8px;border-radius:6px}.languageSelector svg{display:block;flex:none;border:1px solid #c5ccc9;border-radius:2px}.languageSelector a[aria-current=page]{background:#e3eee9;font-weight:700}

.languageSelector .languageFlag{display:block;width:24px!important;height:16px!important;min-width:24px;max-width:24px;flex:0 0 24px;object-fit:fill;border:1px solid #c5ccc9;border-radius:2px;margin:0;padding:0}