/* clarity — white, quiet, one idea per screen. Handwritten headings, a plain sans body, thin
   figures with one warm accent, and a single dark button for moving on. */
:root{--bg:#fff;--ink:#1d1e20;--ink-2:#5e6166;--ink-3:#9a9da2;--line:#ebebeb;--line-2:#dcdcdc;--fill:#f6f6f4;--fill-2:#efefec;
 --accent:#e8693f;--good:#3d8b5a;--good-fill:#eef6f0;--miss:#b4553a;--miss-fill:#fbf0ec;--dark:#26282a;
 --hand:'Patrick Hand',cursive;--sans:'DM Sans',system-ui,sans-serif;--col:680px}
*{box-sizing:border-box}html,body{margin:0;background:var(--bg);color:var(--ink);font-family:var(--sans);-webkit-font-smoothing:antialiased}
button,input{font:inherit;color:inherit}button{cursor:pointer;border:0;background:none;padding:0}a{color:inherit;text-decoration:none}
.sr-only{position:absolute;width:1px;height:1px;clip-path:inset(50%);overflow:hidden}
:focus-visible{outline:2px solid #9aa7b4;outline-offset:3px}
.top{display:flex;align-items:center;gap:18px;height:72px;padding:0 max(20px,calc((100vw - 1040px)/2))}
.wordmark{font:34px var(--hand);letter-spacing:.5px}
.column{width:min(var(--col),calc(100% - 40px));margin:0 auto;padding-bottom:80px}
.hand{font-family:var(--hand);font-weight:400;letter-spacing:-.2px}
/* ——— topic choice ——— */
.home h1{margin:clamp(28px,8vh,72px) 0 28px;font-size:clamp(34px,4.6vw,46px);line-height:1.12}
.search{display:flex;align-items:center;gap:12px;padding:8px 8px 8px 18px;border:1px solid var(--line-2);border-radius:16px;background:#fff;transition:border-color .15s,box-shadow .15s}
.search:focus-within{border-color:#bfc3c8;box-shadow:0 0 0 4px #f1f2f3}
.search-icon{flex:none;width:18px;height:18px;fill:none;stroke:var(--ink-3);stroke-width:1.6;stroke-linecap:round}
.search input{flex:1;min-width:0;border:0;outline:0;background:none;font-size:17px;padding:8px 0}
.search input::placeholder{color:var(--ink-3)}
.explore{flex:none;display:inline-flex;align-items:center;gap:8px;padding:8px 16px;border:1.1px solid #8f9396;border-radius:999px;background:#fff;color:#3a3d40;font-weight:500;font-size:15px;transition:background .15s,color .15s,border-color .15s}
.explore svg{width:14px;height:14px;fill:none;stroke:currentColor;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.explore:not(:disabled):hover{background:#f7f7f6}
.explore:disabled{border-color:transparent;color:#b9bbbe;cursor:default}
.error{color:var(--miss);font-size:14px}
.section{margin:40px 0 12px;font:500 13px var(--sans);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}
.cards{list-style:none;margin:18px 0 0;padding:0;display:grid;gap:10px}
.card{display:flex;align-items:center;gap:18px;width:100%;padding:10px 18px 10px 10px;border:1px solid var(--line);border-radius:16px;background:#fff;text-align:left;font-size:16px;font-weight:500;transition:border-color .15s,background .15s}
.card:hover{border-color:var(--line-2);background:#fcfcfb}
.card canvas{flex:none;width:96px;height:52px;border-radius:10px;background:#fbfbfa}
.card span{flex:1;min-width:0}.card small{display:block;margin-top:3px;font-size:13px;font-weight:400;color:var(--ink-3)}
.card svg{flex:none;width:16px;height:16px;fill:none;stroke:var(--ink-3);stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
/* ——— lesson ——— */
.lesson-top{gap:16px;padding:0 max(14px,calc((100vw - 760px)/2))}
.icon{display:grid;place-items:center;width:36px;height:36px;border-radius:50%}
.icon:hover{background:var(--fill)}
.icon svg{width:20px;height:20px;fill:none;stroke:var(--ink);stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.bar{flex:1;max-width:220px;display:flex;gap:4px}
.bar i{flex:1;height:4px;border-radius:999px;background:var(--line)}
.bar i.done{background:var(--dark)}.bar i.here{background:var(--dark);opacity:.45}
.where{margin-left:auto;font-size:13px;color:var(--ink-3);font-variant-numeric:tabular-nums;letter-spacing:.02em}
.step{padding-top:clamp(8px,4vh,36px)}
.step .title,.step>h1{margin:0 0 12px;font-size:clamp(30px,3.8vw,40px);line-height:1.15}
.body{margin:0 0 12px;font-size:17px;line-height:1.6;color:var(--ink-2)}
.body.muted{color:var(--ink-3);font-size:15px}
.fig{margin:22px -20px 6px;padding:0}
.fig-draw{display:flex;justify-content:center}
.fig-svg{display:block;width:100%;max-width:640px;height:auto;overflow:visible}
.fig-axis{stroke:#d4d4d4;stroke-width:1;stroke-dasharray:4 5;fill:none}.fig-axis.is-frame{stroke-dasharray:none}
.fig-curve{fill:none;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round}
.fig-point{stroke:#fff;stroke-width:2}
.fig-tick{font:12px var(--sans);fill:var(--ink-3)}
.fig-label,.fig-legend text{font:500 14px var(--sans);fill:var(--ink-2)}
.fig-controls{display:flex;flex-wrap:wrap;justify-content:center;gap:12px 32px;margin:12px 20px 0}
.fig-controls:empty{display:none}
.fig-controls label{display:flex;align-items:center;gap:14px;font-size:14px;color:var(--ink-2)}
.fig-controls input{appearance:none;-webkit-appearance:none;width:180px;height:24px;background:none;cursor:ew-resize}
.fig-controls input::-webkit-slider-runnable-track{height:3px;border-radius:999px;background:var(--line-2)}
.fig-controls input::-webkit-slider-thumb{-webkit-appearance:none;width:18px;height:18px;margin-top:-7.5px;border-radius:50%;background:#fff;border:1.5px solid var(--dark);box-shadow:0 1px 3px rgb(0 0 0/.12)}
.fig-controls input::-moz-range-track{height:3px;border-radius:999px;background:var(--line-2)}
.fig-controls input::-moz-range-thumb{width:15px;height:15px;border-radius:50%;background:#fff;border:1.5px solid var(--dark)}
.fig-controls input:disabled{opacity:.35;cursor:not-allowed}
.fig-controls output{min-width:34px;font-size:15px;font-weight:500;color:var(--ink);font-variant-numeric:tabular-nums}
.fig-replay{display:flex;align-items:center;gap:12px;width:min(420px,100%);margin:16px auto 0;padding:7px 16px 7px 7px;border-radius:999px;background:var(--fill);font-size:14px;color:var(--ink-2)}
.fig-replay[hidden]{display:none}
.fig-replay .play{display:grid;place-items:center;width:32px;height:32px;border-radius:50%;background:#fff;box-shadow:0 1px 2px rgb(0 0 0/.1);font-size:11px;color:var(--ink)}
.fig-replay time{margin-left:auto;color:var(--ink-3);font-variant-numeric:tabular-nums}
.interaction{margin-top:22px;padding-top:18px;border-top:1px solid var(--line)}
.prompt{margin:0 0 12px;font-size:17px;font-weight:500}
.options{display:grid;gap:10px}
.option{display:block;width:100%;padding:14px 18px;border:1px solid var(--line-2);border-radius:14px;background:#fff;text-align:center;font-size:16px;line-height:1.4;transition:border-color .15s,background .15s}
button.option:hover{border-color:#b9bcc0;background:#fcfcfb}
.options.is-answered .option{color:var(--ink-3)}
.option.is-right{border-color:#bcdcc6;background:var(--good-fill);color:var(--ink)!important}
.option.is-wrong{border-color:#ecc9bd;background:var(--miss-fill);color:var(--ink)!important}
.verdict{display:flex;align-items:center;gap:10px;margin:20px 0 6px}
.verdict h2{margin:0;font-size:32px}
.verdict-mark svg{display:block;width:28px;height:28px;fill:none;stroke-width:1.6;stroke-linecap:round;stroke-linejoin:round}
.verdict.good .verdict-mark svg{stroke:var(--good)}.verdict.miss .verdict-mark svg{stroke:var(--miss)}
.verdict.enter{animation:verdict .45s cubic-bezier(.2,.8,.2,1)}
@keyframes verdict{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
.hint{margin:0 0 10px;padding:12px 16px;border-radius:12px;background:var(--fill);font-size:15px;line-height:1.5;color:var(--ink-2)}
.hint.nudge{animation:nudge .35s}
@keyframes nudge{25%{transform:translateX(-4px)}75%{transform:translateX(4px)}}
.actions{display:flex;justify-content:flex-end;margin-top:22px}
.primary{display:inline-flex;align-items:center;gap:10px;padding:13px 22px;border-radius:999px;background:var(--dark);color:#fff;font-size:15px;font-weight:500;transition:transform .15s,background .15s}
.primary:hover{background:#000;transform:translateY(-1px)}
.primary svg{width:16px;height:16px;fill:none;stroke:currentColor;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round}
.preparing{display:flex;flex-direction:column;align-items:center;text-align:center;padding-top:clamp(20px,8vh,80px)}
.preparing-art{width:min(360px,80%);height:150px;margin-bottom:18px}
.preparing h1{font-size:clamp(26px,3.2vw,34px);margin:0 0 8px}
.walked{margin:18px 0 0;padding-left:22px;font-size:16px;line-height:2;color:var(--ink-2)}
/* boards in the lesson */
.fig .board{width:100%;padding:0 20px}
.b-comp h3{margin:0 0 10px;font:500 12px var(--sans);letter-spacing:.06em;text-transform:uppercase;color:var(--ink-3)}
.b-pick-hint{font:400 12px var(--sans);text-transform:none;letter-spacing:0;color:var(--ink-3);margin-left:6px}
.b-table{width:100%;border-collapse:collapse;font-size:14px}
.b-table th{text-align:left;font:500 12px var(--sans);color:var(--ink-3);padding:6px 10px;border-bottom:1px solid var(--line-2)}
.b-table td{padding:9px 10px;border-bottom:1px solid var(--line)}
.b-log{list-style:none;margin:0;padding:0;border:1px solid var(--line);border-radius:12px;overflow:hidden;font:13px/1.5 ui-monospace,Menlo,monospace}
.b-log li{display:grid;grid-template-columns:auto auto 1fr;gap:12px;padding:7px 12px;border-bottom:1px solid var(--line)}
.b-log li:last-child{border-bottom:0}.b-log time{color:var(--ink-3)}.b-log b{font-weight:600}
.b-seq,.b-graph{display:block;width:100%;height:auto;overflow:visible}
.b-actor{fill:var(--fill);stroke:none}.b-actor-label{font:500 14px var(--sans);fill:var(--ink)}
.b-lifeline{stroke:var(--line-2);stroke-dasharray:3 5}
.b-arrow{fill:none;stroke:var(--ink-2);stroke-width:1.4;stroke-linecap:round;stroke-linejoin:round}
.b-msg-label,.b-edge-label{font:13px var(--sans);fill:var(--ink-2);paint-order:stroke;stroke:#fff;stroke-width:5px}
.b-hit{fill:transparent}
.b-edge{fill:none;stroke:#b5b8bc;stroke-width:1.3}
.b-node rect{fill:#fff;stroke:var(--line-2);stroke-width:1.2}.b-node text{font:500 14px var(--sans);fill:var(--ink)}.b-node .b-node-state{font:11px var(--sans);fill:var(--accent)}
.b-mem{display:flex;flex-wrap:wrap;gap:6px;padding-top:28px}
.b-cell{position:relative;display:flex;flex-direction:column;align-items:center;min-width:56px;padding:10px 8px 7px;border:1px solid var(--line-2);border-radius:10px}
.b-cell b{font:600 15px ui-monospace,Menlo,monospace}.b-cell small{font-size:11px;color:var(--ink-3)}.b-cell.is-blank b{color:transparent}
.b-ptr{position:absolute;bottom:calc(100% + 2px);left:50%;transform:translateX(-50%);display:flex;flex-direction:column;align-items:center;font:500 12px var(--sans);color:var(--accent);white-space:nowrap}
.b-ptr i{font-style:normal}
.board{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(100%,280px),1fr));gap:22px}.board.is-stacked{grid-template-columns:1fr}
.is-hot td,.b-log li.is-hot,.b-cell.is-hot{background:#fdf1ea}.b-node.is-hot rect{fill:#fdf1ea;stroke:#efb9a2}.b-msg.is-hot .b-arrow{stroke:var(--accent)}
[data-select]{cursor:pointer}[data-select]:hover td,.b-log li[data-select]:hover{background:#fafaf8}
.is-picked td,.b-log li.is-picked,.b-cell.is-picked{background:#eaf1fb}.b-log li.is-picked,tr.is-picked td:first-child{box-shadow:inset 3px 0 0 #4f7fc0}
.b-node.is-picked rect{fill:#eaf1fb;stroke:#4f7fc0}.b-msg.is-picked .b-arrow{stroke:#4f7fc0}
.b-caption{margin:14px 20px 0;font-size:15px;color:var(--ink-2)}.b-caption span{margin-right:8px;font-size:12px;color:var(--ink-3)}
@media(max-width:600px){.top{height:60px;padding:0 14px}.wordmark{font-size:30px}.column{width:calc(100% - 32px)}.fig{margin:16px -8px 4px}.fig-controls input{width:140px}.home h1{margin-top:24px}.card canvas{width:76px;height:44px}.b-log li{grid-template-columns:auto 1fr}.b-log li span{grid-column:1/-1}}
@media(prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}}

/* ——— pass 2: own-words answers, code, labs, follow-ups, where next ——— */
.secondary{padding:13px 20px;border-radius:999px;border:1px solid var(--line-2);background:#fff;font-size:15px;font-weight:500;color:var(--ink)}
.secondary:hover{background:#fafaf9}
.actions{gap:10px}
.text-link{display:block;margin:14px auto 0;font-size:14px;color:var(--ink-3);text-decoration:underline;text-underline-offset:3px}
.text-link:hover{color:var(--ink)}
.say{display:block;width:100%;min-height:96px;resize:vertical;padding:14px 16px;border:1px solid var(--line-2);border-radius:14px;font:16px/1.55 var(--sans);color:var(--ink);outline:none}
.say:focus{border-color:#bfc3c8;box-shadow:0 0 0 4px #f1f2f3}
.said{margin:0 0 4px;padding:10px 16px;border-left:2px solid var(--line-2);font-size:16px;line-height:1.55;color:var(--ink-2)}
.verdict.partial .verdict-mark svg{stroke:#c08a2e}.verdict-mark .half{fill:#c08a2e;stroke:none;opacity:.35}
.primary:disabled{background:#c9cbcd;cursor:default;transform:none}
/* code */
.code-step{margin:22px 0 0}
.signature{margin:0 0 10px;font:14px/1.5 ui-monospace,Menlo,monospace;color:var(--ink-2)}
.editor{display:block;width:100%;min-height:240px;resize:vertical;padding:16px 18px;border:1px solid var(--line-2);border-radius:14px;background:#fbfbfa;font:14px/1.7 ui-monospace,'SF Mono',Menlo,monospace;color:var(--ink);white-space:pre;tab-size:4;outline:none}
.editor:focus{border-color:#bfc3c8;background:#fff}
.code-tools{display:flex;align-items:center;gap:14px;margin-top:12px}
.py-status{font-size:13px;color:var(--ink-3)}
.tests{list-style:none;margin:14px 0 0;padding:0;display:grid;gap:6px;font-size:14px}
.tests li{padding:9px 14px;border-radius:10px;background:var(--fill)}
.tests li span{display:inline-block;width:18px;font-weight:600}
.tests .pass span{color:var(--good)}.tests .fail span{color:var(--miss)}
.tests code{display:block;margin-top:4px;font:12.5px/1.5 ui-monospace,Menlo,monospace;color:var(--ink-2);white-space:pre-wrap;overflow-wrap:anywhere}
/* labs */
.fig-metrics{display:flex;flex-wrap:wrap;justify-content:center;gap:8px;margin:14px 20px 0}
.fig-metrics:empty{display:none}
.fig-metrics span{padding:7px 14px;border-radius:999px;background:var(--fill);font-size:13px;color:var(--ink-3)}
.fig-metrics b{margin-left:6px;font-weight:600;color:var(--ink);font-variant-numeric:tabular-nums}
.lab-state{transition:opacity .2s}.lab-state.is-running{opacity:.55}
.lab-waiting,.lab-error{display:flex;align-items:center;justify-content:center;gap:8px;min-height:160px;font-size:15px;color:var(--ink-3)}
.lab-error{flex-direction:column;color:var(--miss);text-align:center;padding:0 8%}.lab-error span{font:13px/1.5 ui-monospace,Menlo,monospace;color:var(--ink-2)}
.lab-dot{width:6px;height:6px;border-radius:50%;background:var(--ink-3);animation:dot 1.2s infinite ease-in-out}.lab-dot:nth-child(2){animation-delay:.15s}.lab-dot:nth-child(3){animation-delay:.3s}
@keyframes dot{0%,100%{opacity:.25}50%{opacity:1}}
.lab-caption{text-align:center}
/* follow-up field and sheet */
.ask{display:flex;align-items:center;gap:10px;margin-top:40px;padding:6px 6px 6px 16px;border:1px solid var(--line-2);border-radius:999px;background:#fff}
.ask:focus-within{border-color:#bfc3c8;box-shadow:0 0 0 4px #f1f2f3}
.ask input{flex:1;min-width:0;border:0;outline:0;background:none;font-size:15px;padding:8px 0}
.ask input::placeholder{color:var(--ink-3)}
.send{display:grid;place-items:center;flex:none;width:34px;height:34px;border-radius:50%;border:1px solid var(--line-2);color:var(--ink)}
.send:disabled{color:var(--ink-3);border-color:transparent;cursor:default}
.send svg{width:15px;height:15px;fill:none;stroke:currentColor;stroke-width:1.7;stroke-linecap:round;stroke-linejoin:round}
.reopen{margin-top:10px}
body.sheet-open{overflow:hidden}
.sheet{position:fixed;inset:0;z-index:20;background:rgb(255 255 255/.72);backdrop-filter:blur(6px);animation:fade .2s ease}
@keyframes fade{from{opacity:0}}
.sheet-inner{display:flex;flex-direction:column;width:min(var(--col),100%);height:100%;margin:0 auto;background:#fff;box-shadow:0 0 0 1px var(--line),0 30px 80px -40px rgb(0 0 0/.25);animation:rise .28s cubic-bezier(.2,.8,.2,1)}
@keyframes rise{from{transform:translateY(16px);opacity:0}}
.sheet-top{display:flex;align-items:center;gap:12px;height:64px;padding:0 18px;border-bottom:1px solid var(--line)}
.sheet-top .where{margin-left:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}
.thread{flex:1;overflow:auto;padding:22px 24px}
.thread .q{width:fit-content;max-width:85%;margin:0 0 16px auto;padding:11px 16px;border-radius:16px 16px 4px 16px;background:var(--fill);font-size:15px;line-height:1.5}
.thread .a{margin:0 0 22px;font-size:16px;line-height:1.6;color:var(--ink)}
.thread .a p{margin:0 0 10px}
.thread .a-fig{margin:-8px -10px 22px}
.thread .thinking{display:flex;gap:6px;padding:6px 0}.thread .thinking span{width:6px;height:6px;border-radius:50%;background:var(--ink-3);animation:dot 1.2s infinite}.thread .thinking span:nth-child(2){animation-delay:.15s}.thread .thinking span:nth-child(3){animation-delay:.3s}
.sheet-ask{margin:0 18px 18px}
/* where next */
.next-cards{margin-top:24px}
.next-cards .card{position:relative;padding-right:22px}
.next-cards .card span{font-size:16px}
.tag{position:absolute;top:-9px;left:14px;padding:2px 9px;border-radius:999px;background:#fff;border:1px solid var(--line-2);font:500 11px var(--sans);font-style:normal;letter-spacing:.03em;color:var(--ink-2)}
.finish{padding-left:18px}
@media(max-width:600px){.sheet-inner{box-shadow:none}.thread{padding:18px 16px}.editor{font-size:13px;min-height:200px}}

/* ——— pass 3: before we start, your path ——— */
.kicker{margin:0 0 10px;font:500 12px var(--sans);letter-spacing:.08em;text-transform:uppercase;color:var(--ink-3)}
.body .muted{color:var(--ink-3)}
.choose{margin-top:22px}
.choose .option{text-align:left;padding-left:20px}
.choose .option[aria-pressed=true]{border-color:var(--dark);background:#fafaf9;box-shadow:inset 0 0 0 1px var(--dark)}
.own{display:block;margin-top:14px}
.own input{width:100%;padding:13px 18px;border:1px solid var(--line-2);border-radius:14px;font-size:16px;outline:none}
.own input:focus{border-color:#bfc3c8;box-shadow:0 0 0 4px #f1f2f3}
.map-open{margin-left:4px}
.leave{margin-left:2px}.leave svg{width:18px;height:18px}
.map-open svg{stroke-width:1.4}
.path-map{position:relative;margin:26px 0 10px}
.path-lines{position:absolute;inset:0;overflow:visible}
.trail{fill:none;stroke:var(--dark);stroke-width:1.4;stroke-linecap:round}
.trail.is-later{stroke:var(--line-2);stroke-dasharray:3 5}
.trail.branch{stroke:#b9bcc0}
.node{stroke-width:1.6}
.node.is-done{fill:var(--dark);stroke:var(--dark)}
.node.is-here{fill:#fff;stroke:var(--accent);stroke-width:2.4}
.node.is-later{fill:#fff;stroke:var(--line-2)}
.path-node{position:absolute;display:flex;flex-direction:column;align-items:flex-start;max-width:calc(100% - 80px);padding:4px 8px;border-radius:8px;text-align:left;font-size:16px;line-height:1.3;color:var(--ink)}
.path-node span{overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:100%}
.path-node small{font-size:12px;color:var(--ink-3)}
.path-node.is-here small{color:var(--accent)}
.path-node:not([disabled]):hover{background:var(--fill)}
.path-node.is-later{color:var(--ink-3);cursor:default}
.map-art{display:block;width:100%;height:120px;margin:8px 0 0;opacity:.85}