@import url('https://fonts.googleapis.com/css2?family=DM+Sans:wght@400;500;600;700&family=Space+Grotesk:wght@400;500;600;700&display=swap');
:root{color-scheme:dark;--bg:#101426;--panel:#1b2038;--muted:#a5acc7;--ink:#f2f0ff;--mint:#8fe9ce;--gold:#ffdc8b;--border:#343a55}*{box-sizing:border-box}body{margin:0;background:radial-gradient(ellipse at 30% 0%,#28234350,transparent 55%),var(--bg);color:var(--ink);font-family:'DM Sans',sans-serif;font-size:16px}button,a,input{ -webkit-tap-highlight-color:transparent}button{font:inherit;cursor:pointer;color:inherit}button:disabled{cursor:not-allowed;opacity:.45}button:focus-visible,a:focus-visible,summary:focus-visible{outline:3px solid var(--gold);outline-offset:4px}button{transition:background .16s,transform .16s}button:hover:not(:disabled){filter:brightness(1.13)}button:active:not(:disabled){transform:translateY(1px)}.topbar{height:88px;border-bottom:1px solid #ffffff0c;display:flex;align-items:center;justify-content:space-between;padding:0 5vw}.brand{color:#faf5ff;text-decoration:none;font:600 34px 'Space Grotesk',sans-serif;letter-spacing:-2px;display:flex;align-items:center;gap:12px}.brand-star{color:var(--mint);font-size:36px}.brand-sub{font:500 12px 'DM Sans',sans-serif;letter-spacing:2px;margin-left:13px;border-left:1px solid #52566c;padding-left:24px;color:var(--muted)}.top-actions{display:flex;align-items:center;gap:24px}.prototype{font-size:11px;letter-spacing:1.3px;color:#858da9}.icon-button{font-size:14px;border:0;background:transparent;color:#bbc1d9;padding:8px 0}.icon-button span{border:1px solid #5a617b;border-radius:50%;display:inline-grid;place-items:center;width:20px;height:20px;margin-left:7px}main{max-width:1600px;margin:auto;padding:38px 5vw 20px}.chapter{display:flex;justify-content:space-between;align-items:center;margin-bottom:30px}.eyebrow{font-size:11px;letter-spacing:2px;font-weight:700;color:var(--mint);margin:0 0 12px}.eyebrow span{color:#5c6789;margin:0 9px}h1{font:500 clamp(26px,2.7vw,42px) 'Space Grotesk',sans-serif;letter-spacing:-1.5px;margin:0 0 10px}h1>span{color:var(--mint)}.intro{color:var(--muted);margin:0;font-size:15px}.mission{display:flex;gap:14px;align-items:center;padding-right:8px}.mission-symbol{font-size:48px;color:var(--gold)}.mission small{display:block;font-size:10px;letter-spacing:1.5px;color:var(--muted);margin-bottom:7px}.mission strong{font-size:16px;font-weight:500}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 360px;gap:24px;align-items:start}.observatory{border:1px solid #3a3c5a;border-radius:16px;overflow:hidden;background:#12182d;box-shadow:0 20px 60px #0002}.board-toolbar{height:53px;display:flex;align-items:center;justify-content:space-between;padding:0 22px;font-size:13px;color:#bdc5df;background:#1b2037;border-bottom:1px solid #343a5533}.live-dot{width:6px;height:6px;border-radius:50%;background:var(--mint);display:inline-block;margin-right:7px;box-shadow:0 0 9px #8fe9ce50}#score{color:var(--gold);font-weight:600}.canvas-wrap{position:relative;aspect-ratio:20/17}canvas{width:100%;height:100%;display:block;touch-action:pan-y}.board-note{position:absolute;bottom:20px;left:24px;font-size:9px;letter-spacing:2px;color:#7382a8;pointer-events:none}.board-note span{border:1px solid #3f4b6b;padding:3px 5px;border-radius:3px;margin-left:7px}.board-footer{height:47px;display:flex;align-items:center;justify-content:space-between;gap:8px;padding:0 20px;font-size:12px;color:#939ebd;border-top:1px solid #343a5550}.legend-line{display:inline-block;width:20px;height:3px;background:var(--mint);margin-right:7px;vertical-align:middle;box-shadow:0 0 10px #8fe9ce55}.notebook{background:linear-gradient(140deg,#232840,#1c2137);padding:23px;border:1px solid var(--border);border-radius:16px}.panel-heading{display:flex;justify-content:space-between;align-items:center}.panel-heading .eyebrow{font-size:9px;letter-spacing:1.6px;color:#a6acc7;margin-bottom:9px}h2{font:500 23px 'Space Grotesk',sans-serif;margin:0;letter-spacing:-.6px}.count{font-size:12px;color:var(--muted);border:1px solid #4a4e68;padding:5px 8px;border-radius:6px;white-space:nowrap}.panel-copy{font-size:13px;color:var(--muted);margin:12px 0 23px}.equation-row{margin:0 0 12px}.equation-input{display:flex;align-items:center;border:1px solid #46516b;border-radius:9px;background:#11172b;padding:0 10px;gap:9px;min-height:52px}.equation-input:focus-within{border-color:var(--mint);box-shadow:0 0 0 2px #8fe9ce18}.equation-dot{width:7px;height:7px;flex-shrink:0;border-radius:50%;background:var(--eq)}.equation-input input{min-width:0;width:100%;background:none;color:#f4f4fe;border:0;outline:0;font:14px ui-monospace,Consolas,monospace;padding:16px 0}.remove{background:none;border:0;color:#7c86a5;font-size:20px;padding:0 2px}.error{font-size:12px;line-height:1.5;color:#ffacae;margin:6px 0 0}.equation-row.invalid .equation-input{border-color:#d57884}.add-button{border:1px dashed #4a526f;border-radius:8px;background:transparent;color:#b8c2dc;width:100%;font-size:13px;padding:12px;margin-top:0}.examples{display:flex;gap:6px;align-items:center;margin-top:15px;flex-wrap:wrap}.examples span{font-size:11px;color:#8f9ab7;margin-right:auto}.examples button{font-size:11px;border:1px solid #404a67;border-radius:5px;background:#282f4b;padding:4px 7px;color:#c4cce2}.divider{height:1px;background:#3c425a;margin:23px 0 17px}.attempt-meta{display:flex;justify-content:space-between;font-size:11px;color:#a5b0cc;margin-bottom:19px}.attempt-meta b{font-weight:500;color:#d7ddef}.primary{width:100%;border:0;border-radius:8px;background:var(--mint);color:#153b39;font-size:14px;font-weight:700;padding:16px;box-shadow:0 5px 20px #7ce2c510}.primary span{margin-left:12px;font-size:18px}.reset{background:transparent;border:0;width:100%;font-size:13px;color:#b7c0da;margin-top:9px;padding:10px}.status{min-height:16px;font-size:11px;text-align:center;color:#8c97b7;line-height:1.5;margin:5px 0 0}.nova-note{display:flex;gap:10px;align-items:center;padding:22px 5px 18px}.nova-note img{width:88px;height:105px;object-fit:contain;filter:drop-shadow(0 0 15px #c4a5ff20)}.nova-label{font-size:9px;color:var(--gold);font-weight:700;letter-spacing:1.6px}.nova-note p{font-size:13px;line-height:1.7;color:#b9c1db;margin:7px 0}.nova-note button{padding:0;background:none;border:0;border-bottom:1px solid #756b55;color:var(--gold);font-size:12px}.math-guide{border-top:1px solid #343a55;padding-top:15px;color:#aeb9d6;font-size:13px}.math-guide summary{cursor:pointer;list-style:none;display:flex;justify-content:space-between;padding:0 6px}.math-guide>div{font-size:13px;line-height:1.65;padding:5px}.math-guide code{display:block;color:var(--mint);white-space:normal;overflow-wrap:anywhere;font-size:12px;margin:5px 0}.page-footer{display:flex;justify-content:space-between;color:#6e7a9d;font-size:11px;padding:24px 1px}.result{position:absolute;left:50%;top:48%;transform:translate(-50%,-50%);width:min(85%,390px);text-align:center;padding:30px 25px;background:#20243bef;backdrop-filter:blur(12px);border:1px solid #8fe9ce60;border-radius:16px;box-shadow:0 20px 70px #070a20aa}.result>span{font-size:42px;color:var(--gold)}.result h2{margin:10px 0}.result p{font-size:14px;line-height:1.6;color:#c1c9e1}.result button{background:var(--mint);border:0;color:#173c39;font-size:14px;font-weight:600;padding:12px 22px;border-radius:7px}dialog{background:#20253d;color:var(--ink);border:1px solid #56617f;border-radius:18px;max-width:500px;width:calc(100% - 32px);padding:32px;box-shadow:0 20px 100px #0008}dialog::backdrop{background:#080c21b8;backdrop-filter:blur(7px)}dialog ol{padding-left:22px}dialog li,dialog>p:not(.eyebrow){font-size:15px;line-height:1.7;color:#bac5e0;margin-bottom:14px}dialog b{color:#f1effc}.close{position:absolute;right:16px;top:10px;background:none;border:0;font-size:28px;color:#aeb6d2}[hidden]{display:none!important}@media(min-width:1500px){.workspace{grid-template-columns:minmax(0,1fr) 390px}}@media(max-width:1050px){main{padding:28px 3vw}.topbar{padding:0 3vw}.workspace{grid-template-columns:minmax(0,1fr) 320px;gap:16px}.notebook{padding:18px}.canvas-wrap{aspect-ratio:20/20}.prototype{display:none}.mission{display:none}.brand-sub{font-size:10px}}@media(max-width:760px){.topbar{height:68px;padding:0 5vw}.brand{font-size:28px;gap:8px}.brand-sub{display:none}.top-actions{gap:18px}.icon-button{font-size:12px}main{padding:25px 4vw 12px}.chapter{margin-bottom:23px}h1{font-size:28px}.intro{font-size:13px}.workspace{grid-template-columns:1fr;gap:20px}.canvas-wrap{aspect-ratio:20/17}.board-toolbar{height:44px;padding:0 14px}.board-footer{padding:0 12px;font-size:10px;height:38px}.board-note{font-size:8px;bottom:12px;left:15px}.notebook{padding:20px}.panel-copy,.equation-input input,.reset{font-size:14px}.examples button{font-size:12px;padding:6px 12px}.attempt-meta{font-size:12px}.primary{font-size:16px}.nova-note{max-width:450px;margin:auto}.page-footer{font-size:10px;gap:20px}.eyebrow{font-size:10px}}@media(prefers-reduced-motion:reduce){*{transition:none!important}}
.level-controls{display:flex;align-items:center;justify-content:space-between;gap:10px;border-top:1px solid #3c425a;margin-top:10px;padding-top:14px;font-size:12px;color:#aeb9d6}.level-controls button{border:1px solid #596380;background:#2b3450;border-radius:6px;padding:8px;color:#e1e7fa;font-size:12px}.level-controls+ .status{margin-top:12px}
.level-nav{display:flex;align-items:center;gap:14px;margin:0 0 22px;flex-wrap:wrap}.level-nav label{font-size:14px;color:var(--mint)}.level-nav select{font:inherit;font-size:14px;color:var(--ink);background:#232840;border:1px solid #596380;border-radius:8px;padding:12px;max-width:100%;min-width:0}.level-nav span{font-size:13px;color:var(--muted)}#solution{margin-top:14px}#next-level{margin:10px 0 0 8px}.level-nav select:focus-visible{outline:3px solid var(--gold)}@media(max-width:760px){.level-nav{gap:9px}.level-nav select{width:100%}.level-nav span{width:100%}}

.generation-note{position:absolute;z-index:3;inset:0;display:grid;place-items:center;text-align:center;padding:30px;background:#13182de8;color:var(--mint);font-size:16px;line-height:1.6;backdrop-filter:blur(3px)}.level-controls button{width:100%}.level-nav span{line-height:1.5}.form-hint{font-size:13px;color:var(--muted);margin:-6px 0 20px}.form-hint summary{cursor:pointer;color:var(--gold);padding:6px 0}.form-hint code{display:block;overflow-wrap:anywhere;white-space:normal;font-size:13px;line-height:1.6;color:var(--mint);padding:8px 0}.form-hint p{line-height:1.5;margin:2px 0}
#parameter-sliders label{display:block;margin:10px 0}#parameter-sliders input{width:100%;accent-color:var(--mint)}.form-hint label{display:block;margin:12px 0}.form-hint output{float:right}#resolved-equation{overflow-wrap:anywhere;color:var(--mint)}
/* Keep the whole coordinate plane visible; the notebook scrolls separately. */
@media(min-width:761px){body{height:100dvh;overflow:hidden}.topbar{height:60px}main{height:calc(100dvh - 60px);padding:16px 3vw 10px;display:flex;flex-direction:column}.chapter{margin-bottom:12px}.chapter .eyebrow{margin-bottom:5px}h1{font-size:28px;margin-bottom:5px}.level-nav{margin-bottom:12px}.level-nav select{padding:8px}.workspace{flex:1;min-height:0;align-items:stretch}.observatory{display:flex;flex-direction:column;min-height:0}.canvas-wrap{flex:1;min-height:0;aspect-ratio:auto}.board-toolbar,.board-footer{flex-shrink:0;height:38px}.controls{overflow-y:auto;min-height:0;padding-right:5px}.page-footer{padding:8px 0;font-size:10px}.result{max-height:95%;overflow:auto;padding:12px}}
@media(max-width:760px){.canvas-wrap{aspect-ratio:auto;height:min(52dvh,80vw)}.topbar{height:54px}main{padding-top:12px}.chapter{margin-bottom:12px}.level-nav{margin-bottom:12px}.board-toolbar{font-size:11px}.board-footer{font-size:9px}.result{max-height:95%;overflow:auto;padding:12px}}
.form-hint h3{font-size:13px;color:var(--gold);margin:0}.form-hint summary{cursor:pointer}
@media(min-width:761px){.workspace{grid-template-columns:360px minmax(0,1fr);height:100%}.left-panel{grid-column:1;grid-row:1;display:flex;flex-direction:column;min-height:0}.observatory{grid-column:2;grid-row:1}.left-heading{flex-shrink:0;padding:0 10px 10px 0}.left-heading .chapter{display:block;margin-bottom:12px}.left-heading h1{font-size:25px}.left-heading .mission{display:none}.left-heading .intro{font-size:12px}.left-heading .level-nav{gap:7px;margin:0}.left-heading .level-nav select{width:100%}.left-heading .level-nav span{font-size:11px}.left-panel .controls{flex:1;overflow-y:auto}.topbar{height:50px}main{height:calc(100dvh - 50px);padding:12px 2vw 6px}}
@media(max-width:760px){.left-panel{display:contents}.left-heading{grid-row:1}.observatory{grid-row:2}.controls{grid-row:3}.left-heading .chapter{margin-bottom:8px}.left-heading .mission{display:none}.workspace{gap:12px}}
/* Give spare horizontal graph space to the tools on wide screens. */
@media(min-width:1100px){
 main{max-width:none;padding-left:18px;padding-right:18px}
 .workspace{gap:18px;grid-template-columns:clamp(360px,calc(100% - 114.286dvh + 187px),52%) minmax(0,1fr)}
 .left-heading .level-nav{display:grid;grid-template-columns:auto minmax(0,1fr);gap:6px 12px}
 .left-heading .level-nav span{grid-column:2}
 .left-heading .chapter{margin-bottom:8px}
 .notebook{padding:16px 20px}
 .panel-copy{margin:8px 0 14px}
 .form-hint{margin:0 0 12px}
 .equation-input{min-height:44px}
 .equation-input input{padding:12px 0}
 .add-button{padding:9px}
 .examples{margin-top:10px}
 .divider{margin:12px 0}
 .attempt-meta{margin-bottom:10px}
 .primary{padding:12px}
 .reset{padding:7px;margin-top:5px}
 .level-controls{padding-top:9px;margin-top:6px}
 .nova-note{padding:12px 4px;align-items:center}
 .nova-note img{width:60px;height:72px}
 .nova-note p{line-height:1.45}
}
/* Two parts controls, three parts plane; keep primary actions together. */
@media(min-width:761px){
 .workspace{grid-template-columns:minmax(0,2fr) minmax(0,3fr);gap:16px}
 .left-panel{min-width:0}.left-heading{padding-bottom:8px}
 .left-heading .chapter{margin-bottom:6px}.left-heading h1{font-size:23px}
 .left-heading .level-nav{display:grid;grid-template-columns:auto minmax(0,1fr);gap:4px 10px}
 .left-heading .level-nav span{grid-column:2}
 .notebook{padding:12px 14px;position:relative}
 .panel-heading .eyebrow,.panel-copy,.divider{display:none}
 .panel-heading{margin-bottom:8px}.panel-heading h2{font-size:20px}
 .form-hint{margin:0 0 8px}.equation-row{margin-bottom:6px}
 .equation-input{min-height:38px}.equation-input input{padding:9px 0}
 #drop{padding:10px;margin-bottom:7px}
 .add-button{padding:7px}.examples{margin-top:7px;gap:5px}
 .attempt-meta{margin:9px 0 4px}
 .reset{padding:6px;margin-top:0}
 .level-controls{margin-top:3px;padding-top:6px}
 .level-controls button{padding:6px}
 .nova-note{padding:7px 0;gap:6px}.nova-note img{width:42px;height:48px}
 .nova-note p{font-size:11px;line-height:1.35;margin:3px 0}
 .math-guide{padding-top:7px}
 .experiment[open]{position:absolute;z-index:5;inset:8px 8px auto;background:#20263d;border:1px solid #596380;border-radius:10px;padding:12px;max-height:calc(100dvh - 240px);overflow:auto;box-shadow:0 12px 35px #0008}
 #parameter-sliders{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:0 14px}
}
.board-footer{justify-content:center;gap:12px;height:auto;min-height:44px;flex-wrap:wrap;padding:6px 10px}
.board-footer #solution{width:auto;margin:0;padding:6px 9px;font-size:11px;border-style:solid}
.board-footer #pointer{display:none}
@media(max-width:760px){.board-footer{gap:6px}.board-footer #solution{font-size:10px}}
/* Keep all three footer items, with the reveal action at the true center. */
.board-footer{display:grid;grid-template-columns:minmax(0,1fr) auto minmax(0,1fr);align-items:center;gap:8px}
.board-footer>span:first-child{justify-self:start;min-width:0}
.board-footer #solution{justify-self:center;max-width:100%;white-space:normal}
.board-footer #pointer{display:block;justify-self:end;white-space:nowrap;font-variant-numeric:tabular-nums}
@media(max-width:1050px){.board-footer{font-size:9px;gap:5px;padding:6px}.board-footer #solution{font-size:10px;max-width:135px;padding:5px}.board-footer .legend-line{width:12px;margin-right:4px}}
/* Short landscape screens keep controls reachable instead of clipping the page. */
@media(orientation:landscape) and (max-height:600px){body{height:auto;overflow:auto}main{height:calc(100dvh - 96px);min-height:330px}.workspace{min-height:270px}.left-heading h1{font-size:20px}.topbar{height:44px}}