/* Responsive layer: same lessons and calculations, comfortable from 320px. */
:root{--ink:#193c35;--muted:#4f645b;--paper:#fafbf6;--line:#dce3d8;--green:#d9ed95;--focus:#70459a}
html{scroll-padding-top:24px}body{font-family:system-ui,-apple-system,BlinkMacSystemFont,'Segoe UI',sans-serif;line-height:1.5;padding-bottom:calc(84px + env(safe-area-inset-bottom))}*{min-width:0}img,svg{max-width:100%}button,input,select{font-family:inherit}button,select,summary,.button,.hintbtn,.textbutton{min-height:44px}button,select,input[type=number],input[type=time]{font-size:16px}button{white-space:normal}a,button,input,select,summary{touch-action:manipulation}input[type=range]{min-height:44px;touch-action:pan-y;margin:10px 0}input[type=range]::-webkit-slider-thumb{min-width:26px;min-height:26px}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid var(--focus);outline-offset:3px}[hidden]{display:none!important}
.skip-link{position:absolute;top:-100px;left:16px;z-index:1000;background:var(--ink);color:white;padding:12px}.skip-link:focus{top:8px}header{gap:12px;padding:18px 24px;flex-wrap:wrap}header nav{flex-wrap:wrap;gap:8px 20px}header nav a{display:inline-flex;align-items:center;min-height:44px}.brand{white-space:nowrap}.grade{font-size:10px}main{width:calc(100% - 32px);max-width:1160px;margin:0 auto!important}h1{font-size:clamp(2.5rem,7vw,4rem);letter-spacing:-.05em}h2{font-size:clamp(1.6rem,4vw,2.25rem)}p,button,a,span{overflow-wrap:break-word}.hero{padding:40px 0;gap:28px}.heroart{transform:none;width:100%;min-height:0}.spark{right:4px;top:-24px}.decorcircle{width:clamp(80px,25vw,150px);flex-shrink:1}.artcircles{gap:8px}.subject-horizon{padding:20px;background:#edf2e5;border-radius:16px;border:0;margin-bottom:32px;gap:10px}.subject-horizon span{font-size:13px;background:white;padding:7px 11px;border-radius:18px}.subject-horizon span:not(:first-of-type){color:#5b6558}.topics{grid-template-columns:1fr;gap:14px}.topic{padding:22px;background:#e9f2d8}.topic p{font-size:15px;min-height:0}.topic b{font-size:13px}.topic .pill{position:static;display:inline-block;font-size:9px;letter-spacing:.6px}.topicicon{height:45px;float:left;margin-right:16px}.topic h3{clear:both}.topic .pill{margin-top:8px}.lesson{gap:24px;padding-top:48px}.lab{padding:20px}.models{gap:8px}.models figure{width:44%}.models figcaption{font-size:26px}.models small{font-size:12px}.sliderlabel{flex-wrap:wrap;gap:8px;font-size:14px}.rangeends,.fine,.micro,.muted{font-size:13px}.presets{flex-wrap:wrap;margin:16px 0}.presets button{font-size:15px}.insight span{font-size:14px}.lessonintro>p:not(.eyebrow){font-size:16px}.notice p{font-size:15px}.quiz{padding:22px 18px}.quiz h3{font-size:clamp(1.2rem,4vw,1.6rem)}.answers{grid-template-columns:1fr}.answer{font-size:17px;min-height:54px}.quizactions{flex-wrap:wrap;gap:10px}.quiztop{flex-wrap:wrap;gap:10px}.hintbtn,.textbutton,.next{font-size:14px}.sectiontitle{gap:12px}.hero .intro{font-size:17px}.sectiontitle .muted{display:block}.geocard p,.geocard .explain{font-size:15px}.geocard{padding:18px}.geometry .controls{display:block}.geometry .controls>label{display:flex}.controls{gap:10px}.controls button{max-width:100%}.geobutton{font-size:15px}.stats{margin:12px 0}.stat strong{font-size:24px}.drawtoolbar{flex-wrap:wrap}.journey{flex-wrap:wrap;font-size:13px}.gardenheading{flex-wrap:wrap;font-size:11px}.rectstage,.gardenstage{height:auto;min-height:220px;aspect-ratio:1.2}.geometry .rectstage svg,.geometry .gardenstage svg{height:100%;max-height:420px}.samestage{height:auto;min-height:150px}.geometry .samestage svg{height:auto;max-height:260px}.geometry .questiondrawing svg{height:100%}.geometry select{font-size:16px}.activitynav{grid-template-columns:1fr 1fr}.activitynav a{min-height:48px;font-size:13px;display:flex;align-items:center}.tilegrid,.decimal-grid{touch-action:pan-y}.tilegrid.draw-enabled,.decimal-grid.draw-enabled{touch-action:none}.tile{touch-action:inherit}.drawing-tools{padding:12px 0;display:flex;gap:8px;align-items:center;flex-wrap:wrap}.drawing-tools button{border:1px solid #9aae80;border-radius:9px;padding:10px;background:white;color:var(--ink)}.drawing-tools button[aria-pressed=true]{background:var(--ink);color:white}.drawing-tools p{font-size:13px;margin:0}.tilegrid button,.decimal-grid button{min-height:0!important;min-width:0!important}.decimal-grid button{touch-action:inherit}.decimal-grid{width:100%;max-width:360px}.model{width:100%;max-width:360px;flex-shrink:1}.model-row{gap:20px}.panel{padding:14px}.workbench{padding:20px 14px}.workbench>p,.subtext{font-size:15px}.activity-nav{grid-template-columns:1fr 1fr;gap:8px}.activity-nav button{font-size:14px;padding:12px;min-height:64px}.modes{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:7px}.modes button{font-size:14px;padding:10px 6px}.place-mat{gap:6px}.place{padding:12px 4px;font-size:12px}.place button{min-width:44px;margin:4px 0;padding:10px}.place strong{font-size:30px}.controls input[type=number],.controls select{font-size:16px;max-width:100%}.readout{font-size:clamp(1.25rem,5vw,1.6rem)}.track{margin-left:18px;margin-right:18px}.tick{font-size:12px}.track .tick:nth-of-type(odd){font-size:0}.pin{font-size:15px}.mini-shop{grid-template-columns:1fr}.item button{min-width:70px}.vessel-row>div{min-width:0;flex:1 1 220px}.clock-row{gap:10px}.measure-svg text{font-size:16px}.measure-result,.measure-status{padding:14px;font-size:15px}.measure-path{font-size:15px}.measure-path span{padding:10px}.measure-controls{align-items:flex-start}.conversion-bar{max-width:100%}.controls label{display:flex;flex-wrap:wrap;align-items:center;gap:8px}.controls>input{flex-basis:100%}.decimal-hero h1,.geohero h1{font-size:clamp(2.3rem,7vw,3.6rem)}.golden{font-size:15px}.unit-object{font-size:60px}.place.drop-ready{outline:3px solid #70459a;background:#eee6f7}.block[aria-pressed=true]{background:#e7d7f3}.focus-trigger{background:var(--ink);color:white;border:0;border-radius:9px;padding:10px 14px;margin:10px 0}.focus-bar{display:none}.focus-active{overflow:hidden}.focus-active .focus-target{position:fixed!important;inset:0;z-index:300;background:var(--paper);margin:0!important;padding:calc(72px + env(safe-area-inset-top)) max(16px,env(safe-area-inset-right)) calc(24px + env(safe-area-inset-bottom)) max(16px,env(safe-area-inset-left));overflow:auto;overscroll-behavior:contain;width:100%;max-width:none;display:block!important}.focus-active .focus-target>.focus-trigger{display:none}.focus-active .focus-bar{display:flex;position:fixed;inset:0 0 auto;z-index:301;background:var(--ink);color:white;justify-content:space-between;align-items:center;gap:12px;padding:calc(10px + env(safe-area-inset-top)) 16px 10px}.focus-bar button{background:white;color:var(--ink);border:0;border-radius:8px;padding:10px 16px}.focus-active .activitylayout{max-width:1100px;margin:auto}.focus-active .lab{max-width:800px;margin:auto}.bottom-nav{position:fixed;inset:auto 0 0;z-index:100;display:grid;grid-template-columns:repeat(4,1fr);background:#fffef9;border-top:1px solid #d0d9c6;padding:5px max(6px,env(safe-area-inset-right)) calc(5px + env(safe-area-inset-bottom)) max(6px,env(safe-area-inset-left));box-shadow:0 -4px 24px #193c350b}.bottom-nav a{display:flex;align-items:center;justify-content:center;flex-direction:column;min-height:54px;gap:1px;font-size:12px;font-weight:650;border-radius:10px}.bottom-nav a span{font-size:20px;line-height:1.2}.bottom-nav a[aria-current]{background:#edf3e0}.app-tools{display:flex;flex-wrap:wrap;gap:12px;align-items:center;padding:16px 0;font-size:13px;color:var(--muted)}.app-tools a{text-decoration:underline;min-height:44px;display:inline-flex;align-items:center}.app-tools button{border:1px solid #c4d0b5;background:white;border-radius:9px;padding:8px 14px;color:var(--ink)}.app-status{padding:9px 12px;background:#edf3e3;border-radius:9px}.update-banner{position:fixed;left:16px;right:16px;bottom:calc(82px + env(safe-area-inset-bottom));background:var(--ink);color:white;border-radius:14px;padding:16px;z-index:200;box-shadow:0 8px 30px #0003}.update-banner button{margin:6px;background:white;color:var(--ink);border:0;border-radius:8px;padding:10px 14px}.content-page{max-width:820px;padding:32px 0}.content-page h1{font-size:clamp(2rem,6vw,3rem);margin-top:24px}.content-page p{line-height:1.8}.progress-card{background:white;border:1px solid var(--line);border-radius:14px;padding:20px;margin:16px 0}.progress-card h2{font-size:24px}.progress-card a{display:inline-flex;align-items:center;min-height:44px;text-decoration:underline}.progress-card ul{padding-left:20px}.progress-card li{margin:10px 0}.danger-button{border:2px solid #9b432a;background:#fff1e9;color:#742e1c;border-radius:9px;padding:12px 16px}.challenge-links{display:grid;gap:10px}.challenge-links a{display:block;padding:16px;border:1px solid #d0d9c6;border-radius:10px;background:white}.challenges-overview{padding:48px 0}.install-help{background:white;border:1px solid var(--line);padding:20px;border-radius:16px}footer{padding:24px 16px}.focus-active .bottom-nav,.focus-active .update-banner{visibility:hidden}
@media(max-width:600px){header{padding:14px 16px}header nav{display:none!important}header .grade{margin-left:auto}.hero{grid-template-columns:1fr}.heroart{padding:24px 18px}.sectiontitle{flex-direction:column;align-items:flex-start}.lesson{grid-template-columns:1fr}.lessonintro h2{font-size:32px}.geometry .conceptcards,.geometry .activitylayout{grid-template-columns:1fr}.geometry .geosection h2{font-size:27px}.workbench .controls>button{flex:1 1 auto}.geometry .modebuttons{flex-wrap:wrap}.geometry .modebuttons button{padding:10px 12px}.geometry .stats.horizontal{grid-template-columns:1fr}.notice{padding:14px}.notice>span{display:none}.controls>label{flex-basis:100%}.hero .micro{line-height:1.6}}
@media(min-width:540px){.topics{grid-template-columns:1fr 1fr}.mini-shop{grid-template-columns:repeat(3,minmax(0,1fr))}.answers{grid-template-columns:1fr 1fr}.challenge-links{grid-template-columns:1fr 1fr}}
@media(min-width:900px){body{padding-bottom:0}.bottom-nav{position:static;max-width:1160px;margin:24px auto;border:1px solid var(--line);border-radius:16px;padding:5px;box-shadow:none}.bottom-nav a{flex-direction:row;gap:10px}.topics{grid-template-columns:repeat(4,minmax(0,1fr))}.activity-nav{grid-template-columns:repeat(3,minmax(0,1fr))}.update-banner{left:auto;max-width:480px;bottom:20px}.focus-active .activitylayout{grid-template-columns:1fr 1fr}.app-tools{justify-content:flex-end}}
@media(orientation:landscape) and (max-height:600px){.focus-active .activitylayout{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr)}.focus-active .focus-target{padding-top:64px}.focus-active .models{max-height:220px}.focus-active figure svg{max-height:150px}.focus-active .model{max-width:280px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}*,*::before,*::after{animation:none!important;transition:none!important}}
.block{touch-action:none;user-select:none;-webkit-user-select:none}

.models figure{flex:1 1 0;width:auto}.models .equal{flex:0 0 auto}