:root{--ink:#243044;--muted:#5d6879;--paper:#f5f6fa;--line:#dce1ec;--accent:#485ac0;--soft:#eef0ff;--green:#17694c;--warm:#fff4df}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font:17px/1.55 system-ui,-apple-system,"Segoe UI",sans-serif}a{color:#3449a4;text-underline-offset:3px}header{display:flex;justify-content:space-between;align-items:center;gap:20px;padding:20px max(22px,calc((100% - 1180px)/2));background:white;border-bottom:1px solid var(--line)}.brand{font-size:23px;font-weight:750;text-decoration:none;white-space:nowrap}.brand span{display:block;font-size:12px;font-weight:400;color:var(--muted)}main{max-width:1180px;margin:auto;padding:34px 22px 60px}.intro{max-width:790px;margin-bottom:30px}h1{font-size:clamp(34px,5vw,58px);line-height:1.08;letter-spacing:-.035em;font-weight:650;margin:12px 0 22px}h2{font-size:25px;line-height:1.25;margin:0 0 18px}p{margin:0 0 16px}.lead{font-size:20px;color:var(--muted)}.eyebrow{font-size:12px;text-transform:uppercase;letter-spacing:.11em;font-weight:750;color:var(--accent)}.card{background:white;border:1px solid var(--line);border-radius:18px;padding:24px;margin-bottom:22px;min-width:0}.workspace{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:22px;align-items:start}.workspace:focus{outline:0}button,select,input{font:inherit}button{background:var(--accent);color:white;border:1px solid var(--accent);border-radius:10px;padding:11px 16px;font-weight:650;min-height:44px;cursor:pointer}button:hover{filter:brightness(.95)}button.secondary{background:white;color:var(--accent);border-color:#b9c2e0}button.text-button{background:transparent;color:var(--muted);border:0;text-decoration:underline;padding-left:0}button:disabled{opacity:.55;cursor:default}.buttons{display:flex;gap:10px;flex-wrap:wrap;margin:18px 0}label{display:block;font-size:14px;font-weight:650;margin:14px 0 7px}select,input{max-width:100%;min-height:46px;border:1px solid #929eb2;border-radius:9px;background:white;color:var(--ink);padding:9px 12px}select{width:100%;max-width:430px}.answer-line{display:flex;gap:10px;flex-wrap:wrap}.answer-line input{width:170px;font-size:25px;flex:1;min-width:110px}.small{font-size:13px;color:var(--muted);margin-top:10px}.step-line{font-size:13px;color:var(--muted);display:flex;gap:15px;justify-content:space-between;align-items:center;margin-bottom:18px}progress{width:95px;accent-color:var(--accent)}#feedback:not(:empty),#help:not(:empty),#notice:not(:empty){padding:14px;border-radius:10px;background:var(--soft);margin:16px 0}#feedback.error{background:#fff0e9;color:#81371c}#feedback.success{background:#e9f5ed;color:var(--green)}#notice:not(:empty){background:var(--warm);border:1px solid #ead7ad}#empty{color:var(--muted)}.division-scroll{overflow-x:auto;padding:10px 10px 18px}.division{display:grid;grid-template-columns:max-content minmax(3ch,max-content);gap:0;font:30px/1.65 ui-monospace,"SFMono-Regular",Consolas,monospace;max-width:100%;width:max-content;margin:auto}.working{padding:0 16px 0 1ch}.right-side{border-left:2px solid var(--ink);padding-left:13px;align-self:start;min-width:3ch}.divisor{border-bottom:2px solid var(--ink);padding-bottom:3px;min-width:3ch}.quotient{color:var(--accent);padding-top:3px;white-space:nowrap}.number-row{display:grid;position:relative;grid-template-columns:repeat(var(--cols),1ch);min-height:1.55em;white-space:pre}.number-row span{white-space:pre}.number-row .active{background:#ffe7ae;border-radius:4px}.number-row .used{color:#8892a1}.number-row.product::before{content:'−';position:absolute;left:-1ch}.number-row.product span{border-bottom:1px solid var(--ink)}.number-row.partial{color:var(--accent)}.number-row.remainder{color:var(--green)}.board-note{font-size:13px;color:var(--muted);margin-top:18px}.normalization{display:grid;gap:12px}.normalization p{border:1px solid var(--line);border-radius:10px;padding:14px;margin:0}.normalization strong{color:var(--accent)}.stats{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}.stat{background:var(--paper);border-radius:12px;padding:16px}.stat strong{display:block;font-size:29px;color:var(--accent)}.stat span{font-size:13px;color:var(--muted)}.history-item{border-bottom:1px solid var(--line);padding:12px 0;font-size:14px}.history-item small{display:block;color:var(--muted)}footer{font-size:13px;color:var(--muted);padding-top:14px}footer p{margin-top:15px}.skip{position:absolute;left:15px;top:-100px;background:white;padding:12px;z-index:2}.skip:focus{top:10px}:focus-visible{outline:3px solid #b77726;outline-offset:3px}[hidden]{display:none!important}
@media(max-width:780px){main{padding:24px 16px 40px}.workspace{grid-template-columns:1fr;gap:0}.card{padding:20px}.intro{margin-bottom:24px}.division{font-size:28px}.lead{font-size:18px}header{padding:16px}.stats{gap:8px}.stat{padding:12px}.stat span{font-size:12px}}@media(max-width:390px){.card{padding:17px}.division{font-size:25px}.working{padding-right:12px}.right-side{padding-left:9px}.stats{grid-template-columns:1fr}.stat{display:flex;align-items:center;gap:14px}.stat strong{min-width:30px}.buttons button{width:100%}}