:root{--nav-h:60px;--board:#1d2623;--board-edge:#2a3531;--chalk:#efece3;--chalk-2:#efece3bd;--chalk-3:#efece399;--chalk-faint:#efece31a;--chalk-accent:#f2a688;--surface-line:var(--ink);--surface-accent:var(--accent);--ease-out:cubic-bezier(.16, 1, .3, 1);--ease-ink:cubic-bezier(.65, 0, .35, 1);--ease-stamp:cubic-bezier(.2, 1.5, .35, 1);--graph-line:#466ea51a;--graph-strong:#466ea533}@media (prefers-color-scheme:dark){:root:not([data-theme=light]){--board:#1c2724;--board-edge:#2c3834;--graph-line:#ebe7dc0b;--graph-strong:#ebe7dc17}}:root[data-theme=dark]{--board:#18211f;--board-edge:#26302d;--graph-line:#ebe7dc0b;--graph-strong:#ebe7dc17}html{scroll-padding-top:calc(var(--nav-h) + 12px)}@media (prefers-reduced-motion:no-preference){html:has(.landing){scroll-behavior:smooth}}.landing{overflow-x:clip}.landing main:focus{outline:none}.l-wrap{width:100%;max-width:1240px;margin-inline:auto;padding-inline:16px}.l-section{padding-block:clamp(64px,8.5vw,116px)}.l-h2{letter-spacing:-.024em;max-width:16em;font-size:clamp(2.05rem,4.6vw,3.5rem);font-weight:500;line-height:1.04}.l-h3{letter-spacing:-.015em;font-size:clamp(1.45rem,2.6vw,1.9rem);font-weight:500}.l-text{color:var(--ink-2);max-width:36em;font-size:1.075rem;line-height:1.62}.sheet{--margin-x:34px;min-width:0;padding:22px 16px 22px calc(var(--margin-x) + 12px);border:1px solid var(--rule);background-color:var(--sheet);background-image:linear-gradient(to right, transparent calc(var(--margin-x) - 1px), var(--seyes-margin) calc(var(--margin-x) - 1px), var(--seyes-margin) var(--margin-x), transparent var(--margin-x)), repeating-linear-gradient(to bottom, transparent 0 31px, var(--seyes-strong) 31px 32px), repeating-linear-gradient(to bottom, transparent 0 7px, var(--seyes-line) 7px 8px), repeating-linear-gradient(to right, transparent 0 31px, var(--seyes-line) 31px 32px);border-radius:4px;margin:0;position:relative;box-shadow:0 1px #1b21300a,0 24px 48px -28px #1b213052,0 4px 12px -8px #1b213024}.board{isolation:isolate;color:var(--chalk);background-color:var(--board);border:1px solid var(--board-edge);background-image:radial-gradient(60% 45% at 18% 12%,#ffffff0e,#0000 70%),radial-gradient(50% 40% at 85% 88%,#ffffff0a,#0000 70%),linear-gradient(104deg,#0000 32%,#ffffff06 44%,#0000 58%),url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='180' height='180'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='2' stitchTiles='stitch'/%3E%3CfeColorMatrix values='0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 .05 0'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");border-radius:18px;position:relative;box-shadow:inset 0 1px #ffffff0a,inset 0 -14px 30px -18px #00000080,0 30px 60px -36px #1018168c}.board ::selection{color:var(--chalk);background:#f2a68859}.board :focus-visible{outline-color:var(--chalk-accent)}.l-nav{z-index:30;height:var(--nav-h);background:color-mix(in oklab, var(--paper) 90%, transparent);border-bottom:1px solid color-mix(in oklab, var(--rule) 70%, transparent);-webkit-backdrop-filter:saturate(140%)blur(10px);backdrop-filter:saturate(140%)blur(10px);position:sticky;top:0}.l-nav-in{align-items:center;gap:12px;height:100%;display:flex}.l-nav .brand{margin-right:auto;font-size:1.22rem}.l-nav-links{gap:4px;display:none}.l-nav-links a,.l-nav-login{min-height:44px;color:var(--ink-2);border-radius:var(--radius-s);transition:color .16s var(--ease);align-items:center;padding:0 10px;font-size:.95rem;font-weight:600;text-decoration:none;display:inline-flex}.l-nav-links a:hover,.l-nav-login:hover{color:var(--ink)}.l-nav-links a[aria-current=page]{color:var(--ink);box-shadow:inset 0 -2px 0 var(--accent);border-radius:0}.l-nav-tools{align-items:center;gap:2px;display:flex}.l-lang{border:1px solid var(--rule-strong);border-radius:999px;padding:2px;display:inline-flex}.l-lang button{min-width:34px;min-height:30px;color:var(--ink-3);letter-spacing:.06em;background:0 0;border:0;border-radius:999px;font-size:.75rem;font-weight:700}.l-lang button[aria-pressed=true]{background:var(--ink);color:var(--on-ink)}@media (max-width:419px){.l-nav .brand-beta,.l-nav .l-brand-name{display:none}}.l-nav-cta{min-height:40px;padding:0 14px;font-size:.9rem;display:none}.hero{padding-top:12px}.hero-board{grid-template-areas:"art""text";align-content:center;gap:4px;padding:14px 20px 28px;display:grid}.board-ghosts{border-radius:inherit;pointer-events:none;z-index:-1;font-family:var(--font-text);color:var(--chalk);font-style:italic;position:absolute;inset:0;overflow:hidden}.board-ghosts span{white-space:nowrap;opacity:.07;filter:blur(.6px);font-size:clamp(1.6rem,3.2vw,2.6rem);position:absolute}.board-ghosts span:first-child{top:7%;right:6%;rotate:-4deg}.board-ghosts span:last-child{bottom:6%;left:5%;rotate:3deg}@media (max-width:899px){.board-ghosts span:first-child{display:none}}.hero-text{grid-area:text;align-content:center;gap:16px;min-width:0;display:grid}.hero-eyebrow{letter-spacing:.14em;text-transform:uppercase;color:var(--chalk-accent);font-size:.78rem;font-weight:700}.hero-title{letter-spacing:-.028em;color:var(--chalk);text-wrap:balance;text-shadow:0 0 1px #efece340;font-size:clamp(2.3rem,10.4vw,5rem);font-weight:460;line-height:1.04}.h-em{color:var(--chalk-accent);white-space:nowrap;padding-bottom:.06em;font-style:italic;font-weight:500;position:relative}.h-underline{width:104%;height:.32em;position:absolute;bottom:-.16em;left:-2%;overflow:visible}.h-underline path{fill:none;stroke:var(--chalk-accent);stroke-width:2.4px;stroke-linecap:round;opacity:.85}.hero-lead{color:var(--chalk-2);max-width:31em;font-size:1.02rem;line-height:1.58}.hero-ctas{flex-wrap:wrap;gap:10px;margin-top:8px;display:flex}.hero-art{grid-area:art;grid-template-rows:auto auto;min-width:0;display:grid}.hero-art-frame{height:180px;position:relative}.hero-axes,.hero-static,.hero-canvas{width:100%;height:100%;position:absolute;inset:0}.hero-static path{fill:none;stroke:var(--chalk);stroke-width:2.6px;stroke-linecap:round;stroke-linejoin:round;vector-effect:non-scaling-stroke}.hero-axes path{fill:none;stroke:var(--chalk);stroke-width:1px;stroke-linecap:round;vector-effect:non-scaling-stroke;opacity:.16}.hero-canvas{opacity:0;transition:opacity .6s var(--ease)}.hero-board[data-live] .hero-canvas{opacity:1}.hero-caption{display:none}.btn-lg{border-radius:var(--radius-m);min-height:52px;padding:0 22px;font-size:1rem}.btn-chalk{background:var(--chalk);color:#18201d;transition:background-color .16s var(--ease), transform .42s var(--ease-out), box-shadow .2s var(--ease);box-shadow:0 10px 24px -14px #0009}.btn-chalk:hover{background:#fff}.btn-chalk[data-magnet=on]{transition:background-color .16s var(--ease), transform .14s linear}.btn-chalk svg{transition:transform .22s var(--ease-out)}.btn-chalk:hover svg{transform:translate(3px)}.btn-chalk-quiet{color:var(--chalk);background:0 0;border-color:#efece34d}.btn-chalk-quiet:hover{background:#efece30f;border-color:#efece399}.chalk-chip{min-height:40px;color:var(--chalk-2);transition:border-color .16s var(--ease), color .16s var(--ease);background:0 0;border:1px solid #efece338;border-radius:999px;align-items:center;gap:6px;padding:0 14px;font-size:.85rem;font-weight:600;display:inline-flex}.chalk-chip:hover{color:var(--chalk);border-color:#efece380}.chalk-chip svg{transition:transform .5s var(--ease-out)}.chalk-chip:hover svg{transform:rotate(-200deg)}.story{padding-top:clamp(64px,8.5vw,116px)}.story-track{position:relative}.story-sentinel{width:1px;left:0;top:calc(var(--i) * 70vh);top:calc(var(--i) * 70svh);pointer-events:none;height:70svh;position:absolute}.story-sentinel[data-index="3"]{height:110svh}.story-stage{gap:28px;display:grid}.story[data-anim] .story-track{height:320svh}.story[data-anim] .story-stage{top:var(--nav-h);height:calc(100vh - var(--nav-h));height:calc(100svh - var(--nav-h));grid-template-rows:auto 1fr;align-content:start;gap:14px;padding-block:14px;position:sticky}.story-copy{align-content:start;gap:22px;min-width:0;display:grid}.story-steps{--p:1;--q:1;isolation:isolate;gap:6px;margin:0;padding:0;list-style:none;display:grid;position:relative}.story-step-btn{text-align:left;width:100%;color:inherit;border-radius:var(--radius-s);background:0 0;border:0;grid-template-columns:34px 1fr;gap:12px;padding:8px 10px 8px 0;display:grid}button.story-step-btn{cursor:pointer}.story-num{border:1px solid var(--rule-strong);background:var(--paper);width:34px;height:34px;font-family:var(--font-text);color:var(--ink-2);transition:background-color .24s var(--ease), color .24s var(--ease), border-color .24s var(--ease);border-radius:50%;place-items:center;font-size:1.15rem;font-weight:600;display:grid}.story-step-text{gap:2px;padding-top:5px;display:grid}.story-step-text strong{font-family:var(--font-text);font-size:1.28rem;font-weight:600;line-height:1.2}.story-step-text span{color:var(--ink-2);font-size:.96rem;line-height:1.5}.story[data-anim] .story-step{transition:opacity .3s var(--ease)}.story[data-anim] .story-step:not([data-active]) .story-step-text,.story[data-anim] .story-step:not([data-active]) .story-step-text span{color:var(--ink-3)}.story-step-text,.story-step-text span{transition:color .3s var(--ease)}.story[data-anim] .story-step[data-done] .story-num,.story[data-anim] .story-step[data-active] 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auto;grid-template-areas:"label label""code send";align-items:center;gap:4px 10px;padding:8px 8px 8px 12px;display:grid}.st-composer-label{letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3);grid-area:label;font-size:.72rem;font-weight:700}.st-source{min-height:1.5em;font-family:var(--font-mono);color:var(--ink);white-space:pre;grid-area:code;font-size:.92rem;overflow:hidden}.st-send{background:var(--ink);width:34px;height:34px;color:var(--on-ink);transition:transform .3s var(--ease-stamp);border-radius:50%;grid-area:send;place-items:center;display:grid}.caret{vertical-align:-.15em;background:var(--accent);width:2px;height:1.05em;margin-left:1px;animation:1s step-end infinite caret-blink;display:inline-block}.caret-ink{height:1.3em;margin-left:6px}.st-question{transition:opacity .45s var(--ease), transform .45s var(--ease-out);font-size:1.02rem;font-weight:700}.st-answer{font-family:var(--font-text);gap:2px;font-size:1.12rem;line-height:1.5;display:grid;position:relative}.st-display{scrollbar-width:none;font-size:.86em;overflow:auto hidden}.st-display .katex-display{text-align:left;margin:.35em 0}.st-display .katex-display>.katex{text-align:left}.st-end{flex-wrap:wrap;align-items:center;gap:6px;font-size:.95em;display:flex}.st-final{margin-left:.3em;padding:0 .35em;display:inline-block;position:relative}.pen-circle{pointer-events:none;width:160%;height:196%;position:absolute;top:-48%;left:-30%;overflow:visible}.pen-circle path,.pen-tick path{fill:none;stroke:var(--accent);stroke-width:3.6px;stroke-linecap:round;stroke-linejoin:round;stroke-dasharray:1;stroke-dashoffset:0}.pen-tick{left:calc(-1 * var(--margin-x) - 4px);width:26px;height:26px;position:absolute;bottom:2px}.st-line{transition:clip-path .9s var(--ease-ink), opacity .24s var(--ease);transition-delay:calc(var(--k) * .52s)}.st-check{border:1px solid var(--rule);border-radius:var(--radius-m);background:color-mix(in oklab, var(--paper) 70%, var(--sheet));transition:opacity .4s var(--ease), transform .5s var(--ease-out);gap:6px;padding:10px 12px;display:grid}.st-check-head{color:var(--ink-2);align-items:center;gap:8px;font-size:.82rem;font-weight:700;display:flex}.st-check{position:relative}.st-running{color:var(--ink-3);opacity:0;transition:opacity .2s var(--ease);align-items:center;gap:6px;font-weight:600;display:inline-flex;position:absolute;top:10px;right:12px}.st-check[data-running] .st-running{opacity:1}.tool-spinner{border:2px solid var(--rule-strong);border-top-color:var(--accent);border-radius:50%;width:12px;height:12px;animation:.8s linear infinite spin-soft}.st-code{font-family:var(--font-mono);color:var(--ink);overflow-wrap:anywhere;min-height:2.6em;font-size:.8rem}.st-prompt{color:var(--accent-ink);font-weight:700}.st-result{transition:opacity .3s var(--ease);flex-wrap:wrap;align-items:center;gap:6px 10px;display:flex}.st-out{font-family:var(--font-mono);font-size:.95rem;font-weight:700}.st-equal{min-height:24px;font-size:.75rem}.st-role{color:var(--ink-3);flex-basis:100%;font-size:.78rem}.st-role code{font-family:var(--font-mono);color:var(--ink-2);overflow-wrap:anywhere;font-size:.95em}.st-stamp-row{justify-content:space-between;align-items:center;gap:12px;display:flex}.st-stamp{min-height:40px;box-shadow:0 0 0 3px color-mix(in oklab, var(--ok) 14%, transparent);margin:0;padding:4px 16px 4px 12px;font-size:1.02rem;position:relative;transform:rotate(-4deg)}.st-stamp:after{content:"";border-radius:inherit;border:2px solid var(--ok);opacity:0;pointer-events:none;position:absolute;inset:-3px}.st-replay{border:1px solid var(--rule-strong);background:var(--paper);min-height:36px;color:var(--ink-2);border-radius:999px;align-items:center;gap:6px;padding:0 12px;font-size:.82rem;font-weight:600;display:inline-flex}.story[data-anim] .st-composer:not([data-sent])~.st-question{opacity:0;transform:translateY(8px)}.story[data-anim] .st-composer[data-sent]{opacity:.55}.story[data-anim] .st-composer[data-sent] .st-send{transform:scale(.86)}.story[data-anim] .story-stage:not([data-s0]) .st-composer{opacity:.4}.story[data-anim] .story-stage:not([data-s1]) .st-line{clip-path:inset(-40px 100% -40px 0);opacity:0;transition-delay:0s}.story[data-anim] .story-stage[data-s1] .st-line{clip-path:inset(-40px -40px -40px 0)}.story[data-anim] .story-stage:not([data-s2]) .st-check{opacity:0;transform:translateY(14px)}.story[data-anim] .st-check:not([data-done]) .st-result{opacity:0}.story[data-anim] .story-stage:not([data-s3]) .st-stamp{opacity:0;transform:scale(1.6)rotate(-12deg)}.story[data-anim] .story-stage:not([data-s3]) .pen-circle path,.story[data-anim] .story-stage:not([data-s3]) .pen-tick path{stroke-dashoffset:1px}.story[data-anim] .pen-circle path{transition:stroke-dashoffset .7s var(--ease-ink) 80ms}.story[data-anim] .pen-tick path{transition:stroke-dashoffset .38s var(--ease-ink) .7s}html[data-motion] .story[data-anim] .story-stage[data-s3] .st-stamp{animation:stamp .56s var(--ease-stamp) .52s both}html[data-motion=full] .story[data-anim] .story-stage[data-s3] .st-stamp:after{animation:ink-ring .7s var(--ease-out) .76s both}.story-legend{gap:26px;padding-top:clamp(56px,8vw,96px);display:grid}.story[data-anim] .story-legend{padding-top:24px}.legend-list{gap:20px;margin:0;display:grid}.legend-list>div{border-top:1px solid var(--rule);gap:8px;padding-top:16px;display:grid}.legend-list dt{margin:0}.legend-list dd{color:var(--ink-2);max-width:34em;margin:0;line-height:1.55}.modes-grid{gap:28px;display:grid}.modes-side{align-content:start;gap:24px;display:grid}.modes-tabs{gap:8px;display:grid}.mode-tab{--mx:50%;--my:50%;border-radius:var(--radius-l);text-align:left;width:100%;color:var(--ink-2);transition:background-color .22s var(--ease), border-color .22s var(--ease), color .22s var(--ease);background:0 0;border:1px solid #0000;grid-template-columns:42px 1fr;align-items:start;gap:12px;padding:12px 14px;display:grid;position:relative;overflow:hidden}.mode-tab:before{content:"";background:radial-gradient(260px circle at var(--mx) var(--my), color-mix(in oklab, var(--mode) 12%, transparent), transparent 70%);opacity:0;transition:opacity .3s var(--ease);pointer-events:none;position:absolute;inset:0}.mode-tab:hover:before{opacity:1}.mode-tab:hover{color:var(--ink)}.mode-tab[aria-selected=true]{background:var(--sheet);border-color:var(--rule);color:var(--ink);box-shadow:var(--shadow)}.mode-tab-icon{border:1px solid color-mix(in oklab, var(--mode) 40%, transparent);width:42px;height:42px;color:var(--mode);transition:background-color .22s var(--ease), color .22s var(--ease);border-radius:50%;place-items:center;display:grid}.mode-tab[aria-selected=true] .mode-tab-icon{background:var(--mode);color:var(--sheet)}.mode-tab-text{gap:3px;display:grid}.mode-tab-text strong{font-family:var(--font-text);font-size:1.32rem;font-weight:600;line-height:1.2}.mode-tab-text span{font-size:.93rem;line-height:1.5}.modes-sheet{view-transition-name:modes-sheet;min-height:400px}.modes-sheet:focus-visible{outline-offset:4px}.panel{align-content:start;gap:16px;display:grid}.panel-title{font-family:var(--font-text);font-size:1.4rem;font-weight:600}.scheme{gap:8px;display:grid}.scheme-head{letter-spacing:.1em;text-transform:uppercase;color:var(--accent-ink);justify-content:flex-end;font-size:.72rem;font-weight:700;display:flex}.scheme-list{gap:10px;margin:0;padding:0;list-style:none;display:grid}.scheme-row{font-family:var(--font-text);grid-template-columns:1fr auto;align-items:baseline;gap:12px;font-size:1.1rem;line-height:1.45;display:grid}.scheme-n{font-weight:700}.scheme-pts{font-family:var(--font-ui);color:var(--accent-ink);white-space:nowrap;border:1.5px solid;border-radius:999px;padding:1px 9px;font-size:.85rem;font-weight:700}.scheme-total{border-top:2px solid var(--accent);font-family:var(--font-text);justify-content:space-between;align-items:baseline;margin-top:8px;padding-top:10px;font-size:1.2rem;font-weight:600;display:flex}.scheme-total strong{color:var(--accent-ink);font-size:1.9rem}.panel-q{font-weight:700}.solve-list{gap:12px;margin:0;padding:0;list-style:none;display:grid}.solve-row{align-items:center;gap:10px;min-width:0;font-size:1.05rem;display:flex}.solve-math{scrollbar-width:none;min-width:0;padding-block:4px;overflow:auto hidden}.solve-check{background:var(--ok-wash);width:24px;height:24px;color:var(--ok);border-radius:50%;flex:none;place-items:center;display:grid}.solve-badge{justify-self:start;margin:4px 0 0}.tutor-student{background:var(--ink);max-width:85%;color:var(--on-ink);border-radius:14px 14px 4px;justify-self:end;padding:10px 14px;font-size:.98rem}.hint-list{gap:10px;margin:0;padding:0;list-style:none;display:grid}.hint{border-left:3px solid var(--ok);background:color-mix(in oklab, var(--ok-wash) 60%, transparent);border-radius:0 var(--radius-m) var(--radius-m) 0;gap:2px;padding:10px 14px;display:grid}.hint-label{letter-spacing:.08em;text-transform:uppercase;color:var(--ok);font-size:.72rem;font-weight:700}.hint-text{font-family:var(--font-text);font-size:1.1rem;line-height:1.45}.hint-foot{flex-wrap:wrap;align-items:center;gap:12px;display:flex}.hint-meter{color:var(--ink-3);font-size:.8rem}.hint-done{color:var(--ink-2);font-style:italic}.annales-grid{gap:40px;display:grid}.annales-stage{height:400px;position:relative}.papers{place-items:center;display:grid;position:absolute;inset:0}.paper{--margin-x:26px;aspect-ratio:.74;width:min(56%,290px);padding:16px 14px 14px calc(var(--margin-x) + 10px);border:1px solid var(--rule);background-color:var(--sheet);background-image:linear-gradient(to right, transparent calc(var(--margin-x) - 1px), var(--seyes-margin) calc(var(--margin-x) - 1px), var(--seyes-margin) var(--margin-x), transparent var(--margin-x)), repeating-linear-gradient(to bottom, transparent 0 23px, var(--seyes-strong) 23px 24px), repeating-linear-gradient(to bottom, transparent 0 5px, var(--seyes-line) 5px 6px);transform-origin:50% 90%;translate:var(--tx) var(--ty);rotate:var(--r);border-radius:4px;grid-area:1/1;grid-template-rows:auto auto 1fr;align-content:start;gap:10px;display:grid;box-shadow:0 1px #1b21300a,0 18px 36px -22px #1b213066}.paper:first-child{--tx:-44%;--ty:7%;--r:-15deg}.paper:nth-child(2){--tx:-15%;--ty:-2%;--r:-5deg}.paper:nth-child(3){--tx:15%;--ty:-1%;--r:5deg}.paper:nth-child(4){--tx:44%;--ty:8%;--r:15deg}.paper-head{letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3);flex-wrap:wrap;gap:4px 10px;font-size:.66rem;font-weight:700;display:flex}.paper-head 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