:root{--ink:#21313e;--muted:#5a6976;--blue:#2859a5;--green:#477d69;--line:#dce3e8;--paper:#fff;--bg:#f6f4ef}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:18px/1.6 "Times New Roman",Times,serif}a{color:var(--blue)}button,input,select,textarea{font:inherit}button,.button{background:white;border:1px solid #b7c5d0;color:var(--blue);padding:7px 13px;border-radius:7px;cursor:pointer;text-decoration:none;display:inline-block}button:hover,.button:hover{background:#edf3fa}button:disabled{opacity:.45;cursor:default}.primary,.tabs .active{background:var(--blue);color:white}header,main,footer{max-width:1260px;margin:auto;padding:24px}header nav{display:flex;gap:9px;align-items:center;flex-wrap:wrap}#profile{margin-left:auto}.eyebrow{font:700 12px/1.5 Arial,sans-serif;letter-spacing:2px;color:var(--green);margin-top:30px}h1{font-size:48px;line-height:1.15;margin:10px 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.lesson-toolbar{display:grid;grid-template-columns:minmax(0,1fr) 44px;gap:12px;align-items:start}.lesson-complete{padding:6px;width:44px;height:44px;display:grid;place-items:center;background:transparent;border-color:transparent;color:#6b7d8c}.lesson-complete svg{fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}.lesson-complete:hover{color:#2859a5;background:#edf3fa}.lesson-complete.is-complete{color:#fff;background:#477d69;border-color:#477d69}.lesson-complete:focus-visible{outline:3px solid #7aa2df;outline-offset:2px}

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/* A single reading path, rather than a dashboard of unrelated activities. */
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.concept h4{font-size:17px;margin:24px 0 5px;color:var(--green)}.concept h4+p{margin-top:5px}.concept .prose p{margin-top:8px}

.concept table{border-collapse:collapse;width:100%;font-size:16px}.concept th,.concept td{padding:8px 12px;border-bottom:1px solid var(--line);text-align:left}.visual-controls output{min-width:40px}.visual-controls label{min-width:0}
.prose p>.katex{display:inline-block;overflow:visible;vertical-align:baseline;padding:.15em 0}.prose .katex{overflow-wrap:normal;word-break:normal}.katex-display{padding:.35em 0}.concept{min-width:0}.worked-steps{min-width:0}

.reward-status{font-size:14px;margin:12px 0}.reward-badges{display:flex;flex-wrap:wrap;gap:7px}.reward-badges span{padding:5px 10px;border:1px solid var(--line);border-radius:20px;background:white}.reward-badges .earned{color:#6b4e00;background:#fff3d6;border-color:#e3c770}.reward-status details{margin:10px 0;max-width:750px}.reward-status summary{cursor:pointer;color:var(--blue)}.reward-status li{margin:7px 0}.reward-status p{margin:10px 0}#reward-chip{margin-left:auto}#profile{margin-left:0}.ach-pn{font-family:Arial,sans-serif}.ach-pn small{color:inherit}

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.variable-controls{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:10px;margin:16px 0}.variable-control{display:grid;grid-template-columns:minmax(0,1fr) 82px;align-items:center;gap:8px;padding:10px;border:1px solid var(--line);border-radius:8px;background:white}.variable-control.is-active{border-color:var(--blue);background:#edf4fb}.variable-control label{grid-column:1/-1;font-size:16px;cursor:pointer}.variable-control input[type=range]{width:100%;min-width:0}.variable-control input[type=number]{width:82px;min-width:0;font-size:16px;padding:4px;border:1px solid #b7c5d0;border-radius:5px}.variable-control small{grid-column:1/-1;font-size:12px}.visual-stage [data-variable]:focus{outline:2px solid #d08434}.visual-controls [data-active]{display:block;flex-basis:100%}#triple-limit{width:100px;padding:5px}.tablewrap button{font-size:14px;padding:5px 8px}@media(max-width:760px){.variable-controls{grid-template-columns:1fr}.variable-control{grid-template-columns:minmax(0,1fr) 82px}}

/* Long algebraic expressions remain readable without widening the page. */
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.prose p>.katex{padding-right:.18em}


/* Inline math must flow with text, never create a tiny scroll box. */
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.prose p>.katex>.katex-html{white-space:normal}
.prose .katex .base{white-space:nowrap}
.katex-display{padding:.4em .2em;max-width:100%;box-sizing:border-box}
.katex-display>.katex,.katex-display>.katex>.katex-html{white-space:normal}
.choice>span:last-child{overflow:visible;overflow-wrap:anywhere}
/* Only a formula wider than its entire paragraph becomes a scrollable block. */
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.prose p>.katex.math-wide>.katex-html{white-space:nowrap}
.book-diagram{max-width:100%;overflow-x:auto}
.visual .concept>label{display:flex;align-items:center;flex-wrap:wrap;gap:8px;margin:9px 0;min-width:0}.visual .concept>label select{max-width:100%;min-width:0}.visual .concept>label input{max-width:100%;min-width:0}.visual .concept>label input[type=number]{width:108px}.visual .concept>label input[type=range]{flex:1;min-width:100px}@media(max-width:760px){.visual .concept>label{display:grid;grid-template-columns:minmax(0,1fr);gap:4px}.visual .concept>label select,.visual .concept>label input[type=range]{width:100%}}

/* Honor hidden native controls. */
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/* Visible lesson navigation. */
.learning-stages a{display:inline-block;padding:8px 4px;min-height:44px;box-sizing:border-box;color:inherit}.learning-stages a:focus-visible{outline:3px solid #bd7027;outline-offset:3px}#tabs{scroll-margin-top:12px}.lesson-panel>#visual{margin:12px 0 28px}.lesson-panel>.book-diagram{max-width:100%;overflow:auto}

/* Explanatory storyboard controls. */
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/* Lesson playback */
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/* Wrap visual explanations */
.visual p{overflow-wrap:anywhere}

/* Keep numeric diagram entries readable instead of shrinking them on phones. */
.book11-readable-diagram{max-width:100%;overflow-x:auto;overflow-y:hidden;border:1px solid #c4d5e5;border-radius:8px;margin:12px 0;overscroll-behavior-x:contain}
.book11-readable-diagram>svg{display:block;min-width:var(--book11-table-width,783px);max-width:none!important;width:100%!important;height:auto}
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.book11-diagram-tools{margin:12px 0 0}.book11-diagram-tools p{font-size:14px;margin:6px 0}.book11-diagram-tools button{min-height:44px}

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.original-exercise .book-diagram svg,.source-comparison .book-diagram svg{min-width:440px}

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