:root{color-scheme:light;--paper:#faf8f1;--ink:#263d37;--muted:#647069;--line:#dcd9cc;font-family:Arial,sans-serif;color:var(--ink);background:var(--paper);font-synthesis:none}
*{box-sizing:border-box}body{margin:0}a{color:inherit}button{font:inherit;color:inherit;cursor:pointer}a,button{-webkit-tap-highlight-color:transparent}a:focus-visible,button:focus-visible,summary:focus-visible{outline:3px solid #337c9a;outline-offset:4px}.wrap{width:min(1186px,calc(100% - 64px));margin-inline:auto}.skip-link{position:absolute;left:16px;top:-100px;padding:16px;background:#fffdf7;z-index:9}.skip-link:focus{top:8px}
.site-header{height:76px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line)}.wordmark{display:flex;align-items:center;gap:11px;text-decoration:none;font:26px Georgia,serif;letter-spacing:-1px}.ink-mark{font-style:italic;border:1px solid #879890;border-radius:50%;width:32px;height:32px;display:grid;place-items:center;font-size:25px;line-height:1}.header-link{display:flex;align-items:center;gap:14px;min-height:44px;font-size:13px;text-decoration:none}.header-link:hover{text-decoration:underline}
.hero-layout{display:grid;grid-template-columns:minmax(0,.85fr) minmax(0,1.15fr);gap:46px;align-items:center;min-height:588px;padding-block:42px}.hero{padding-bottom:28px}h1{font:400 clamp(38px,4vw,54px)/1.12 Georgia,'Times New Roman',serif;letter-spacing:-1.8px;margin:0}h1 em{font-weight:400;color:#557267}.primary-action{display:inline-flex;align-items:center;gap:28px;min-height:48px;margin-top:28px;padding:14px 23px;border-radius:4px;background:#2e5146;color:#fffdf6;text-decoration:none;font-size:14px}.primary-action:hover{background:#203f35}.showcase{min-width:0}
.subject-switcher{display:flex;justify-content:center;gap:8px;margin:0 auto 14px}.subject-switcher button{min-height:44px;min-width:88px;padding:8px 18px;border:1px solid transparent;border-radius:24px;background:transparent;font-size:13px;color:#647069}.subject-switcher button[aria-pressed=true]{color:#294f43;border-color:#cfcab9;background:#f0eadb}.subject-switcher button:hover{color:#294f43;background:#f3efe3}
.example-scene{background:#fffdf7;border:1px solid #d5d0c0;border-radius:4px 10px 10px 4px;box-shadow:0 4px 0 -1px #e9e5d7,0 8px 0 -3px #dfdacb,0 15px 27px #3a443012;overflow:hidden}.question-page{padding:24px 28px 21px;border-bottom:1px solid var(--line)}.response-page{padding:18px 0 8px}.response-page .notebook-header{padding:0 28px}.notebook-header{display:flex;justify-content:space-between;gap:12px;font-size:10px;letter-spacing:1px;color:#647069;min-height:16px}.problem-label{font:17px/1.4 Georgia,serif;margin:18px 0 8px}.starting-question{font:28px/1.25 Georgia,serif;letter-spacing:-.3px;margin:0;min-height:35px}
#example-canvas{display:block;width:100%;height:220px;background:repeating-linear-gradient(transparent 0,transparent 37px,#eaece1 37px,#eaece1 38px);pointer-events:none}.demo-controls{display:flex;align-items:center;justify-content:space-between;margin:-30px 28px 0;position:relative;z-index:3}.demo-controls button{display:flex;align-items:center;min-height:44px;padding:8px 0;border:0;background:transparent;font-size:12px;color:#566960}.demo-controls button:hover{color:#263d37}.example-transcript{margin:10px auto 0;color:var(--muted);font-size:12px}.example-transcript summary{width:fit-content;margin:auto;display:flex;align-items:center;min-height:44px;cursor:pointer;text-decoration:underline;text-underline-offset:3px}.example-transcript #example-transcript{margin:0 14px 16px;font-size:14px;line-height:1.6}.example-transcript p{margin:8px 0}.site-footer{border-top:1px solid var(--line);padding:18px 0;font-size:11px;line-height:1.6;color:var(--muted)}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
@media(max-width:900px){.hero-layout{gap:28px;grid-template-columns:minmax(0,.8fr) minmax(0,1.2fr)}h1{font-size:39px;letter-spacing:-1.2px}}
@media(max-width:650px){.wrap{width:calc(100% - 32px)}.site-header{height:64px}.wordmark{font-size:23px}.header-link{font-size:12px;gap:8px}.hero-layout{display:block;padding-block:22px 0;min-height:0}.hero{text-align:center;padding:0 0 20px}.desktop-break{display:none}h1{font-size:34px;letter-spacing:-1.2px;line-height:1.14}.primary-action{margin-top:18px;min-height:46px;font-size:13px}.subject-switcher{margin-bottom:10px;gap:3px}.subject-switcher button{font-size:12px;min-width:84px;padding:8px 15px}.question-page{padding:18px 22px}.notebook-header{font-size:9px;letter-spacing:.8px}.problem-label{margin:13px 0 8px;font-size:15px}.starting-question{font-size:24px;min-height:30px;line-height:1.25}.response-page{padding-top:16px}.response-page .notebook-header{padding:0 22px}#example-canvas{height:206px}.demo-controls{margin:-30px 22px 0}.example-transcript{margin-top:8px}.site-footer{text-align:center;padding:13px 0;font-size:10px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important}}
/* A lesson on a tablet, with the learning sequence always in view. */
.hero-layout{padding-block:24px;gap:38px;min-height:0;grid-template-columns:minmax(0,.85fr) minmax(0,1.15fr)}
h1{font-size:clamp(34px,3.5vw,48px);line-height:1.13;letter-spacing:-1.4px}.hero{padding-bottom:0}.learning-promise{font-size:16px;line-height:1.6;color:#566960;margin:20px 0 0}.primary-action{margin-top:22px}
.tablet{position:relative;padding:12px 10px 17px;border:1px solid #263c34;border-radius:27px;background:#35433e;box-shadow:inset 0 0 0 2px #617067,0 14px 30px #25392f16}.tablet-camera{position:absolute;top:4px;left:calc(50% - 2px);width:4px;height:4px;border-radius:50%;background:#172720;box-shadow:0 0 0 1px #68756d}.tablet-home{position:absolute;bottom:6px;left:43%;width:14%;height:3px;background:#7d8b82;border-radius:8px}.tablet-screen{overflow:hidden;border-radius:16px;background:#fffdf7}.subject-switcher{margin:0;padding:5px 8px 0;gap:4px}.subject-switcher button{min-height:40px;min-width:82px;padding:6px 15px}.example-scene{border:0;border-radius:0;box-shadow:none;overflow:visible}.question-page{padding:13px 22px 0}.problem-label{margin:12px 0 5px;font-size:16px}.starting-question{font-size:25px;min-height:32px}.lesson-art{height:91px;margin-top:4px}.lesson-art svg{display:block;width:100%;height:100%}.lesson-art svg[hidden]{display:none}.picture-hint,.picture-understood{opacity:0;transition:opacity .7s ease}.lesson-art [data-step="1"] .picture-hint,.lesson-art [data-step="2"] .picture-hint,.lesson-art [data-step="3"] .picture-hint,.lesson-art [data-step="2"] .picture-understood,.lesson-art [data-step="3"] .picture-understood{opacity:1}.light-ray{stroke-dasharray:120;stroke-dashoffset:120;transition:opacity .7s,stroke-dashoffset 1s}.lesson-art [data-step="1"] .picture-hint.light-ray,.lesson-art [data-step="2"] .light-ray,.lesson-art [data-step="3"] .light-ray{stroke-dashoffset:0}
.learning-flow{display:flex;justify-content:space-between;gap:6px;list-style:none;margin:0;padding:11px 20px 10px;border-bottom:1px solid #e8e5d9;background:#f4f0e5;font-size:11px;color:#58675d}.learning-flow li{display:flex;align-items:center;gap:5px;white-space:nowrap}.learning-flow li span{font-size:10px;border:1px solid #cbd0c3;border-radius:50%;width:18px;height:18px;display:grid;place-items:center}.learning-flow [aria-current="step"]{color:#294f43;font-weight:bold}.learning-flow [aria-current="step"] span{background:#345b49;border-color:#345b49;color:#fffdf7}.learning-flow [data-complete="true"]{color:#466b55}
.response-page{padding:13px 0 0}.response-page .notebook-header{padding:0 22px}.canvas-surface{position:relative}#example-canvas{height:198px}.demo-controls{margin:0 22px;min-height:40px}.demo-controls button{min-height:40px}.example-transcript{margin-top:0}.example-transcript summary{min-height:36px}.site-footer{padding:12px 0}
#demo-stylus{position:absolute;left:0;top:0;pointer-events:none;opacity:0;z-index:2;will-change:transform}#demo-stylus[data-active="true"]{opacity:1}#demo-stylus svg{display:block;width:15px;height:88px;transform-origin:50% 100%;transform:translate(-50%,-100%) rotate(28deg);filter:drop-shadow(3px 3px 2px #253c3020)}
@media(max-width:900px) and (min-width:651px){.hero-layout{gap:22px;grid-template-columns:minmax(0,.8fr) minmax(0,1.2fr)}h1{font-size:36px}.learning-flow{padding-inline:12px;gap:3px;font-size:10px}}
@media(max-width:650px){.wrap{width:calc(100% - 24px)}.site-header{height:54px}.hero-layout{display:block;padding-block:15px 0}.hero{padding:0 0 16px}h1{font-size:30px;line-height:1.12;letter-spacing:-1px}.learning-promise{font-size:13px;line-height:1.4;margin-top:10px}.learning-promise br{display:none}.primary-action{margin-top:13px;min-height:44px;padding:11px 18px}.tablet{padding:10px 7px 14px;border-radius:23px}.tablet-screen{border-radius:14px}.tablet-home{bottom:5px}.tablet-camera{top:3px}.subject-switcher{padding:3px 4px 0}.subject-switcher button{min-height:38px;min-width:78px;font-size:12px}.question-page{padding:11px 16px 0}.problem-label{font-size:14px;margin-top:10px}.starting-question{font-size:21px;min-height:27px}.lesson-art{height:75px;margin-top:2px}.learning-flow{padding:8px 11px;font-size:10px;gap:4px}.learning-flow li{gap:4px}.learning-flow li span{width:16px;height:16px;font-size:9px}.response-page{padding-top:10px}.response-page .notebook-header{padding:0 16px;font-size:9px}#example-canvas{height:184px}.demo-controls{margin-inline:16px}.demo-controls button{font-size:11px}.example-transcript summary{min-height:30px}.site-footer{padding:9px 0}#demo-stylus svg{height:75px;width:14px}}
@media(max-width:350px){h1{font-size:27px}.learning-flow{padding-inline:7px;font-size:9px;gap:2px}.learning-flow li{gap:3px}.starting-question{font-size:19px}.question-page{padding-inline:13px}}
@media(prefers-reduced-motion:reduce){.picture-hint,.picture-understood,.light-ray{transition:none}#demo-stylus{display:none}}

/* Laptop windows (including browser zoom) keep the whole lesson in view. */
@media(min-width:651px) and (max-height:700px){
 .site-header{height:58px}.hero-layout{padding-block:12px}.tablet{padding:10px 8px 14px}.subject-switcher{padding-top:3px}.subject-switcher button{min-height:36px}.question-page{padding:10px 18px 0}.problem-label{font-size:15px;margin:8px 0 4px}.starting-question{font-size:22px;min-height:28px}.lesson-art{height:64px;margin-top:2px}.learning-flow{padding:8px 14px;font-size:10px}.response-page{padding-top:8px}#example-canvas{height:166px}.demo-controls button{min-height:36px}.demo-controls{min-height:36px}.example-transcript summary{min-height:30px}.site-footer{padding:8px 0}
}
@media(min-width:651px) and (max-height:560px){
 .site-header{height:50px}.hero-layout{padding-block:8px}.hero h1{font-size:32px}.learning-promise{font-size:14px;margin-top:12px}.primary-action{margin-top:16px}.question-page{display:grid;grid-template-columns:minmax(0,1fr) 100px;column-gap:8px;padding-bottom:8px}.question-page .notebook-header{grid-column:1/-1}.question-page .lesson-art{grid-column:2;grid-row:2/4;align-self:center;height:65px}.problem-label{font-size:14px}.starting-question{font-size:20px}.learning-flow{padding-block:6px}#example-canvas{height:150px}.site-footer{padding:6px 0}
}

.input-note{font-size:11px;color:var(--muted);margin:12px 0 0}
@media(min-width:651px) and (max-height:560px){.hero-layout{padding-block:6px}}
@media(min-width:901px) and (max-height:560px){.question-page{grid-template-columns:minmax(0,1fr) 200px}}

.ink-mark{border:0;border-radius:9px;display:block;object-fit:contain;background:#263d37}