/* Layout: a teaching workbench — one live cube per section beside the lesson it explains; cube colours are the only bright colour on the page. */
:root{
  --bg:#eef1f6; --surface:#ffffff; --surface-2:#e3e8f1; --ink:#0f1733; --muted:#55607d; --line:#cfd6e4;
  --accent:#2457d6; --accent-ink:#ffffff;
  --c-w:#ffffff; --c-y:#f7c62f; --c-o:#ff6d1f; --c-r:#de4335; --c-b:#3f84f4; --c-g:#16994f; --c-x:#c9cfdb; --plastic:#0f1733;
  --f-display:"Archivo","Arial Narrow",system-ui,sans-serif;
  --f-body:"Atkinson Hyperlegible",system-ui,-apple-system,"Segoe UI",sans-serif;
  --f-mono:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace;
  --r:14px;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#0a0f1f; --surface:#131a30; --surface-2:#1b2440; --ink:#e9edf7; --muted:#9aa5c2; --line:#28324f;
  --accent:#6f9bff; --accent-ink:#0a0f1f; --c-x:#3a4566; --plastic:#05070f; color-scheme:dark }}
:root[data-theme="dark"]{
  --bg:#0a0f1f; --surface:#131a30; --surface-2:#1b2440; --ink:#e9edf7; --muted:#9aa5c2; --line:#28324f;
  --accent:#6f9bff; --accent-ink:#0a0f1f; --c-x:#3a4566; --plastic:#05070f; color-scheme:dark }

*{box-sizing:border-box}
html{scroll-behavior:smooth}
@media (prefers-reduced-motion: reduce){html{scroll-behavior:auto}}
body{background:var(--bg);color:var(--ink);font-family:var(--f-body);font-size:17px;line-height:1.6;padding-inline:20px}
.wrap{max-width:1160px;margin-inline:auto}
h1,h2,h3{font-family:var(--f-display);text-wrap:balance;margin:0;line-height:1.05}
h2{font-size:clamp(30px,4.6vw,52px);font-weight:850;font-stretch:112%;letter-spacing:-.01em}
h3{font-size:22px;font-weight:800;font-stretch:105%}
p{margin:0}
.eyebrow{font-family:var(--f-mono);font-size:12px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted)}
.lede{font-size:clamp(18px,2vw,21px);color:var(--muted);max-width:60ch}
a{color:var(--accent)}
button{font:inherit;color:inherit;cursor:pointer}
:focus-visible{outline:3px solid var(--accent);outline-offset:3px;border-radius:8px}
section{padding-block:clamp(56px,9vw,110px)}
.sec-head{display:grid;gap:14px;margin-bottom:36px;max-width:780px}

/* nav */
nav.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;margin-inline:-20px;padding:10px 20px;background:color-mix(in srgb,var(--bg) 86%,transparent);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
nav.top .wrap{display:flex;align-items:center;gap:18px;justify-content:space-between}
.brand{display:flex;align-items:center;gap:10px;font-family:var(--f-display);font-weight:850;font-stretch:110%;text-decoration:none;color:var(--ink);font-size:16px;white-space:nowrap}
.logo{display:grid;grid-template-columns:repeat(3,7px);gap:2px;padding:3px;background:var(--plastic);border-radius:4px}
.logo i{width:7px;height:7px;border-radius:1.5px;display:block}
.navlinks{display:flex;gap:20px;font-size:15px}
.navlinks a{color:var(--muted);text-decoration:none}
.navlinks a:hover{color:var(--ink)}
.pill{font-family:var(--f-mono);font-size:12px;padding:6px 10px;border-radius:99px;background:var(--surface);border:1px solid var(--line);white-space:nowrap}
@media (max-width:820px){.navlinks{display:none}}

/* buttons */
.btn{display:inline-flex;align-items:center;gap:8px;padding:12px 20px;border-radius:99px;border:1.5px solid var(--ink);background:transparent;font-weight:700;text-decoration:none;color:var(--ink);font-size:16px}
.btn.primary{background:var(--ink);color:var(--bg)}
.btn:hover{transform:translateY(-1px)}
.btn.sm{padding:8px 14px;font-size:14px}
.chip{border:1.5px solid var(--line);background:var(--surface);padding:8px 14px;border-radius:99px;font-size:15px;font-weight:700}
.chip:hover{border-color:var(--ink)}
.chip[aria-pressed="true"]{background:var(--ink);color:var(--bg);border-color:var(--ink)}

/* cube */
.stage{position:relative;display:grid;place-items:center;aspect-ratio:1;width:100%;max-width:440px;margin-inline:auto;perspective:1100px;touch-action:none;cursor:grab;user-select:none}
.stage:active{cursor:grabbing}
.cube{--s:min(52vw,210px);width:var(--s);height:var(--s);position:relative;transform-style:preserve-3d;transition:transform .9s cubic-bezier(.2,.8,.2,1)}
.cube.dragging{transition:none}
.face{position:absolute;inset:0;display:grid;grid-template-columns:repeat(3,1fr);gap:5%;padding:5%;background:var(--plastic);border-radius:10%;backface-visibility:hidden}
.face.U{transform:rotateX(90deg) translateZ(calc(var(--s)/2))}
.face.D{transform:rotateX(-90deg) translateZ(calc(var(--s)/2))}
.face.F{transform:translateZ(calc(var(--s)/2))}
.face.B{transform:rotateY(180deg) translateZ(calc(var(--s)/2))}
.face.R{transform:rotateY(90deg) translateZ(calc(var(--s)/2))}
.face.L{transform:rotateY(-90deg) translateZ(calc(var(--s)/2))}
.st{border-radius:18%;background:var(--c-x);transition:background .45s,opacity .45s,filter .45s;position:relative}
.st.fade{opacity:.16}
.st.dim{opacity:.55}
.st.dim::after{content:"";position:absolute;inset:26%;border:2px solid var(--plastic);border-radius:20%;opacity:.6}
.st.ring::after{content:"";position:absolute;inset:22%;border:2.5px solid rgba(15,23,51,.55);border-radius:22%}
.shadow{position:absolute;bottom:4%;width:60%;height:8%;border-radius:50%;background:radial-gradient(closest-side,rgba(15,23,51,.22),transparent);pointer-events:none}
.hint{font-family:var(--f-mono);font-size:12px;color:var(--muted);text-align:center}
@media (prefers-reduced-motion: reduce){.cube,.st{transition:none}}

/* hero */
.hero{display:grid;grid-template-columns:1.1fr .9fr;gap:40px;align-items:center;padding-block:clamp(40px,7vw,90px) 40px}
.hero h1{font-size:clamp(44px,8vw,96px);font-weight:900;font-stretch:118%;letter-spacing:-.02em;line-height:.95}
.hero h1 em{font-style:normal;color:var(--accent)}
.hero .copy{display:grid;gap:22px;min-width:0}
.cta-row{display:flex;flex-wrap:wrap;gap:12px}
.facts{display:grid;grid-template-columns:repeat(4,1fr);gap:0;border-top:1.5px solid var(--ink);margin-top:10px}
.facts div{padding:14px 12px 0 0}
.facts b{display:block;font-family:var(--f-display);font-size:clamp(24px,3vw,34px);font-weight:850;font-stretch:110%;font-variant-numeric:tabular-nums;line-height:1.1}
.facts span{font-size:13px;color:var(--muted);line-height:1.3;display:block}
.hero-cube{display:grid;gap:12px;justify-items:center}
.ctrls{display:flex;gap:8px;flex-wrap:wrap;justify-content:center}
.status{font-family:var(--f-mono);font-size:13px;min-height:1.6em;text-align:center}
@media (max-width:860px){.hero{grid-template-columns:1fr}.facts{grid-template-columns:repeat(2,1fr)}}

/* thesis */
.thesis{background:var(--ink);color:var(--bg);margin-inline:-20px;padding:clamp(48px,8vw,90px) 20px}
.thesis p.big{font-family:var(--f-display);font-weight:850;font-stretch:115%;font-size:clamp(30px,5.4vw,64px);line-height:1.02;letter-spacing:-.01em;max-width:18ch}
.thesis p.big s{text-decoration-thickness:4px;opacity:.55}
.thesis .sub{margin-top:20px;max-width:58ch;opacity:.8;font-size:18px}

/* method */
.method{display:grid;grid-template-columns:.9fr 1.1fr;gap:40px;align-items:start}
.method .stage{position:sticky;top:90px}
.principles{display:grid;gap:12px;min-width:0}
.pr{display:grid;grid-template-columns:auto 1fr;gap:16px;text-align:left;padding:20px;border-radius:var(--r);border:1.5px solid var(--line);background:var(--surface)}
.pr[aria-pressed="true"]{border-color:var(--ink);box-shadow:4px 4px 0 var(--ink)}
.pr .n{font-family:var(--f-mono);font-size:13px;font-weight:700;width:34px;height:34px;display:grid;place-items:center;border-radius:8px;background:var(--surface-2)}
.pr[aria-pressed="true"] .n{background:var(--ink);color:var(--bg)}
.pr h3{margin-bottom:6px}
.pr p{color:var(--muted);font-size:16px}
.pr .life{margin-top:10px;font-size:15px;color:var(--ink);border-left:3px solid var(--accent);padding-left:12px}
.legend{display:flex;gap:14px;flex-wrap:wrap;justify-content:center;font-family:var(--f-mono);font-size:12px;color:var(--muted)}
@media (max-width:860px){.method{grid-template-columns:1fr}.method .stage{position:relative;top:0;max-width:300px}}

/* lessons */
.progress{display:flex;align-items:center;gap:14px;margin-bottom:18px}
.bar{flex:1;height:8px;border-radius:99px;background:var(--surface-2);overflow:hidden}
.bar i{display:block;height:100%;width:0;background:linear-gradient(90deg,var(--c-w),var(--c-y),var(--c-o),var(--c-r),var(--c-b),var(--c-g));transition:width .6s}
.steps{display:flex;gap:8px;overflow-x:auto;padding-bottom:8px;scrollbar-width:thin}
.stp{flex:0 0 auto;display:flex;align-items:center;gap:8px;padding:9px 14px;border-radius:99px;border:1.5px solid var(--line);background:var(--surface);font-weight:700;font-size:14px;white-space:nowrap}
.stp .dot{width:20px;height:20px;border-radius:50%;display:grid;place-items:center;font-family:var(--f-mono);font-size:11px;background:var(--surface-2)}
.stp.done .dot{background:var(--c-g);color:#fff}
.stp[aria-selected="true"]{border-color:var(--ink);background:var(--ink);color:var(--bg)}
.stp[aria-selected="true"] .dot{background:var(--bg);color:var(--ink)}
.stp-wrap{flex:0 0 auto;display:flex;align-items:stretch;border-radius:99px;border:1.5px solid var(--line);background:var(--surface);overflow:hidden}
.stp-wrap .stp{border:0;border-radius:0;background:transparent;color:inherit}
.stp-wrap.on{border-color:var(--ink);background:var(--ink);color:var(--bg)}
.stp-vid{display:flex;align-items:center;gap:6px;padding:0 14px 0 10px;border-left:1.5px solid var(--line);font-size:13px;font-weight:700;color:inherit;text-decoration:none}
.stp-vid svg{width:22px;height:22px;padding:5px;border-radius:50%;background:#ff0033;fill:#fff}
.stp-vid:hover{background:var(--surface-2);color:var(--ink)}
.stp-vid:focus-visible,.stp-wrap .stp:focus-visible{outline:2px solid var(--accent);outline-offset:-3px}
.stp-wrap.on .stp-vid{border-left-color:color-mix(in srgb,var(--bg) 30%,transparent)}
.lesson{display:grid;grid-template-columns:.85fr 1.15fr;gap:36px;margin-top:22px;background:var(--surface);border:1.5px solid var(--line);border-radius:22px;padding:clamp(18px,3vw,36px)}
.lesson .vis{display:grid;gap:10px;align-content:start}
.lesson .body{display:grid;gap:18px;align-content:start;min-width:0}
.lesson .goal{font-size:19px;font-weight:700}
.how{margin:0;padding-left:20px;display:grid;gap:6px}
.alg{display:flex;flex-wrap:wrap;gap:6px;align-items:center}
.alg code{font-family:var(--f-mono);font-weight:700;font-size:15px;padding:6px 9px;border-radius:7px;background:var(--surface-2)}
.alg .lbl{font-size:13px;color:var(--muted);margin-right:4px}
.finger{font-family:var(--f-mono);font-size:13px;color:var(--muted)}
.callout{padding:16px 18px;border-radius:12px;background:var(--surface-2);display:grid;gap:4px}
.callout .eyebrow{color:var(--accent)}
.practice{display:flex;align-items:center;gap:10px;font-weight:700}
.practice .tag{font-family:var(--f-mono);font-size:12px;padding:4px 8px;border-radius:6px;background:var(--c-y);color:#1a1300}
.lesson-foot{display:flex;flex-wrap:wrap;gap:10px;justify-content:space-between;align-items:center;border-top:1px solid var(--line);padding-top:18px}
.cheer{min-height:1.5em;color:var(--c-g);font-weight:700}
.pl-link{display:inline-flex;align-items:center;gap:10px;width:fit-content;font-weight:700;text-decoration:none;color:var(--ink);padding:8px 16px 8px 8px;border-radius:99px;background:var(--surface);border:1.5px solid var(--line)}
.pl-link svg{width:26px;height:26px;padding:6px;border-radius:50%;background:#ff0033;fill:#fff}
.pl-link:hover{border-color:var(--ink)}
.pl-end{display:flex;justify-content:center;margin-top:22px}
.vbtn{display:grid;grid-template-columns:auto 1fr;gap:14px;align-items:center;margin-top:6px;padding:12px 16px 12px 12px;border-radius:16px;background:var(--surface-2);border:1.5px solid var(--line);color:var(--ink);text-decoration:none;transition:border-color .2s,transform .2s}
.vbtn:hover{border-color:var(--ink);transform:translateY(-1px)}
.vbtn:focus-visible{outline:2px solid var(--accent);outline-offset:3px}
.vb-stage{position:relative;display:grid;place-items:center;width:86px;height:86px;border-radius:12px;background:var(--surface);perspective:400px}
.vb-stage .cube{--s:42px;transition:none}
.vb-stage .face{border-radius:12%}
.vb-stage .st.dim::after{border-width:1px}
.vb-play{position:absolute;right:-6px;bottom:-6px;width:28px;height:28px;border-radius:50%;display:grid;place-items:center;background:#ff0033;box-shadow:0 0 0 3px var(--surface-2)}
.vb-play svg{width:14px;height:14px;fill:#fff;margin-left:2px}
.vb-txt{display:grid;gap:3px;min-width:0}
.vb-txt .eyebrow{font-size:11px}
.vb-txt b{font-family:var(--f-display);font-size:17px;line-height:1.2}
.vb-goal{font-size:13px;color:var(--muted);line-height:1.35;display:-webkit-box;-webkit-line-clamp:2;-webkit-box-orient:vertical;overflow:hidden}
.vb-cta{font-size:13px;font-weight:700;color:var(--accent);margin-top:2px}
.practice a{color:inherit;text-decoration:underline;text-decoration-thickness:2px;text-underline-offset:3px}
@media (prefers-reduced-motion: reduce){.vbtn{transition:none}}
@media (max-width:860px){.lesson{grid-template-columns:1fr}.lesson .stage{max-width:280px}}

/* lab */
.domains{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:22px}
.lab{display:grid;grid-template-columns:1fr 1fr;gap:30px;background:var(--surface);border:1.5px solid var(--line);border-radius:22px;padding:clamp(18px,3vw,36px)}
.lab .left{display:grid;gap:14px;align-content:start;min-width:0}
.lab .right{display:grid;gap:18px;align-content:start;min-width:0}
.scenario{font-size:19px;font-weight:700}
.lenses{display:flex;gap:6px;flex-wrap:wrap}
.lenses .chip{font-size:13px;padding:6px 11px}
.explain{border-radius:14px;background:var(--surface-2);padding:18px;display:grid;gap:8px;min-height:150px}
.explain .k{font-family:var(--f-mono);font-size:12px;letter-spacing:.12em;text-transform:uppercase;color:var(--accent)}
.explain h3{font-size:20px}
.explain ul{margin:0;padding-left:20px}
.ladder{display:grid;gap:6px}
.rung{display:grid;grid-template-columns:auto 1fr;gap:12px;align-items:center;text-align:left;padding:12px 14px;border-radius:12px;border:1.5px solid var(--line);background:var(--surface)}
.rung .lv{font-family:var(--f-mono);font-size:12px;font-weight:700;padding:4px 8px;border-radius:6px;background:var(--surface-2)}
.rung b{display:block}
.rung span{font-size:14px;color:var(--muted)}
.rung:hover{border-color:var(--muted)}
.rung[aria-pressed="true"]{border-color:var(--ink);box-shadow:inset 0 0 0 1px var(--ink)}
.rung[aria-pressed="true"] .lv{background:var(--ink);color:var(--bg)}
.takeaway{font-family:var(--f-display);font-weight:800;font-stretch:108%;font-size:20px;line-height:1.25;border-top:1.5px solid var(--ink);padding-top:14px}
@media (max-width:860px){.lab{grid-template-columns:1fr}.lab .stage{max-width:280px}}

/* timer */
.timer{display:grid;grid-template-columns:1.2fr .8fr;gap:24px;align-items:stretch}
.clock{border-radius:22px;background:var(--ink);color:var(--bg);display:grid;place-items:center;gap:6px;padding:40px 20px;border:none;width:100%}
.clock .t{font-family:var(--f-mono);font-weight:700;font-size:clamp(48px,10vw,104px);font-variant-numeric:tabular-nums;line-height:1}
.clock .s{font-size:14px;opacity:.7}
.clock.run .t{color:var(--c-y)}
.stats{display:grid;gap:10px;align-content:start;background:var(--surface);border:1.5px solid var(--line);border-radius:22px;padding:22px}
.stats .row{display:flex;justify-content:space-between;font-variant-numeric:tabular-nums;border-bottom:1px solid var(--line);padding-bottom:8px}
.stats .row b{font-family:var(--f-mono)}
.times{font-family:var(--f-mono);font-size:14px;color:var(--muted);display:flex;flex-wrap:wrap;gap:8px}
@media (max-width:760px){.timer{grid-template-columns:1fr}}

/* coach */
.coach{display:grid;grid-template-columns:auto 1fr;gap:clamp(24px,5vw,60px);align-items:start}
.avatar{width:clamp(140px,22vw,220px);aspect-ratio:1;border-radius:50%;background:var(--c-y);overflow:hidden;border:4px solid var(--ink)}
.avatar img{width:100%;height:100%;object-fit:cover;display:block}
.coach .txt{display:grid;gap:18px;min-width:0}
.mile{display:grid;grid-template-columns:repeat(4,1fr);gap:0;border-top:1.5px solid var(--ink)}
.mile div{padding:14px 14px 0 0}
.mile .when{font-family:var(--f-mono);font-size:12px;color:var(--muted)}
.mile b{display:block;font-family:var(--f-display);font-weight:800;font-size:17px;line-height:1.2;margin-top:4px}
.quote{font-family:var(--f-display);font-weight:600;font-stretch:96%;font-size:clamp(22px,2.8vw,30px);line-height:1.25;border-left:6px solid var(--c-y);padding-left:20px}
.quote cite{display:block;font-family:var(--f-mono);font-style:normal;font-size:13px;color:var(--muted);margin-top:10px}
@media (max-width:760px){.coach{grid-template-columns:1fr}.mile{grid-template-columns:repeat(2,1fr)}}

/* book */
.book{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin-top:28px}
.offer{border-top:6px solid var(--k);background:var(--surface);border-radius:var(--r);padding:22px;display:grid;gap:8px;align-content:start}
.offer p{color:var(--muted);font-size:16px}
.contact{margin-top:28px;display:flex;flex-wrap:wrap;gap:12px;align-items:center}
.contact code{font-family:var(--f-mono);font-size:16px;padding:10px 14px;background:var(--surface);border:1.5px solid var(--line);border-radius:10px;user-select:all}
@media (max-width:760px){.book{grid-template-columns:1fr}}
footer{padding-block:40px;border-top:1px solid var(--line);color:var(--muted);font-size:14px;display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px}

/* standalone page basics (replaces the artifact host's reset) */
html{-webkit-text-size-adjust:100%}
body{margin:0}
img{max-width:100%}
[hidden]{display:none!important}
:root{padding-top:env(safe-area-inset-top,0px);padding-bottom:env(safe-area-inset-bottom,0px)}