:root{--paper:#f4eddf;--white:#fffcf5;--pine:#16372a;--ink:#21372b;--sage:#dce3d5;--rust:#a64f2a;--muted:#5c6659;--line:#cec8b7;--gold:#d7b775}*{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:25px}body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.65 Arial,sans-serif}button,input,textarea{font:inherit}button,a{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.45}a{color:inherit;text-underline-offset:5px}h1,h2,h3{font-family:Georgia,serif;font-weight:400;line-height:1.08;letter-spacing:-.035em;margin:0 0 20px}h1{font-size:clamp(48px,5.9vw,84px)}h2{font-size:clamp(32px,3.3vw,48px)}h3{font-size:30px}p{margin:0 0 18px}em{color:var(--rust);font-weight:400}button:focus-visible,a:focus-visible,input:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid 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.source-extras{display:flex;justify-content:space-between;gap:15px}.source-extras .text-button{font-size:11px;color:var(--muted)}

/* A quiet first encounter; reveal the machine after the hands-on prediction. */
.getting-started{font-size:14px;max-width:430px;color:var(--muted);margin:20px 0 0}.before-lab{padding:32px;background:var(--sage);border:1px solid #c4cdb8;border-radius:7px}.before-lab h3{font-size:32px}.before-lab li{margin-bottom:14px}.number-help{font-size:14px;color:var(--muted)}.plain-plan{border:1px solid #ccd4c1;border-radius:5px;overflow:hidden;margin:10px 0 20px}.plain-instruction{display:flex;gap:12px;padding:12px;border-bottom:1px solid #dbe0d3;align-items:baseline}.plain-instruction:last-child{border:0}.plain-instruction.next{background:#f2e4c7;box-shadow:inset 3px 0 var(--rust)}.plain-instruction>span{font-size:11px;min-width:65px;color:#70502d}.plain-instruction p{font-size:15px;margin:0;line-height:1.6}.choices{flex-wrap:wrap}.choices .not-sure{font:14px Arial,sans-serif;padding:12px}.instruction-panel .small,.feedback,.lab-disclosure{font-size:14px!important}.text-button,.controls .button{font-size:14px;min-height:44px}.register label{font-size:14px}.deeper summary,.connection summary{font-size:14px;min-height:44px}.jump-lab{display:block;margin:10px 0}.value-controls label{font-size:14px}.value-controls input{min-height:44px}.lesson-navigation .button{font-size:14px;gap:8px}.phase-nav button{font-size:12px}.source-extras{flex-wrap:wrap}.source-extras .text-button{font-size:13px}#phase-title:focus{outline:none}.code-lines{font-size:13px}.controls{margin-top:20px}#code-details{margin-top:0}.lab-disclosure{margin-bottom:12px}
@media(max-width:740px){.phase-nav{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));overflow:visible;gap:4px}.phase-nav button{white-space:normal;font-size:12px;padding:10px 5px;line-height:1.4;min-height:52px}.before-lab{padding:24px}.lesson-navigation{gap:12px}.lesson-navigation .button{max-width:75%}.plain-instruction{gap:8px;padding:10px}.plain-instruction>span{min-width:55px;font-size:10px}.plain-instruction p{font-size:14px}.lab-header{flex-wrap:wrap;gap:5px}.register label{flex-direction:column}.controls .text-button{margin:0}.lesson-progress{min-width:75px}.lab-panel{padding:16px}.getting-started{font-size:14px}}
#back-to-instructions{display:none}@media(max-width:740px){#back-to-instructions{display:block;margin:10px 0}}