:root{--navy:#142843;--blue:#245b91;--pale:#eaf2fa;--paper:#fff;--bg:#f6f4ef;--ink:#1e3045;--muted:#546478;--line:#d7dfe7;--gold:#bd791c;--soft:#fff3df;--green:#176543;--red:#a02c32;--radius:18px}
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9px);width:18px;height:20px;border-radius:8px 8px 0 0;background:var(--navy)}.working .worker{animation:work .5s ease-in-out 2;animation-delay:calc(var(--i)*.04s)}.bar-row{margin:12px 0}.bar-label{display:flex;justify-content:space-between;gap:10px;font-size:.85rem;margin-bottom:6px}.bar-track{height:18px;background:#e8edf1;border-radius:5px;overflow:hidden}.bar-fill{height:100%;background:var(--blue);width:0;transition:width .7s ease}.bar-fill.gold{background:#a76b17}.sample{display:grid;grid-template-columns:repeat(3,1fr);gap:9px}.sample button{min-height:80px;background:white;border:1px solid #b0c0d0;border-radius:10px;display:flex;align-items:center;justify-content:center;gap:8px;flex-direction:column;font-size:.77rem;transition:transform .2s,background .2s}.sample button[aria-pressed="true"]{background:#dcecff;outline:2px solid var(--blue);transform:translateY(-4px)}.shape{width:24px;height:24px;display:block;background:#2860a0}.shape.circle{border-radius:50%}.shape.amber{background:#a36811}.shape.red{background:#b84348}.fraction-select{width:100%;padding:11px;border:1px solid #9fb2c5;border-radius:8px;background:white;margin-top:8px}.mini-map{display:flex;gap:10px;align-items:center;justify-content:center;flex-wrap:wrap;padding:16px 6px;font-weight:650}.mini-map span{padding:10px 14px;border-radius:9px;background:#e8f0f8}.mini-map .transform{background:#fff0d5}.mini-map.reveal span{animation:pop .45s both}.mini-map.reveal span:nth-child(3){animation-delay:.15s}.mini-map.reveal span:nth-child(5){animation-delay:.3s}.celebrate{animation:success .6s ease}.finish{background:var(--navy);color:white;border-radius:14px;padding:24px;margin:0 24px 28px}.finish h3{font-size:1.45rem}.finish p{margin-bottom:0}.print-book{display:none}.storage-note{margin-top:12px;font-size:.76rem;color:var(--muted)}.intro-mark{display:inline-block;color:var(--blue)}dialog{border:1px solid var(--line);border-radius:16px;max-width:min(90vw,440px);padding:28px;color:var(--ink)}dialog::backdrop{background:#14284380}dialog h2{font-size:1.6rem}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.sidebar{max-height:calc(100dvh - 40px);overflow-y:auto;padding-right:4px;scrollbar-width:thin}
@keyframes signal{from{left:-12px}to{left:100%}}@keyframes pop{0%{transform:scale(.93)}65%{transform:scale(1.04)}100%{transform:scale(1)}}@keyframes success{0%,100%{box-shadow:0 0 0 0 #17654300}50%{box-shadow:0 0 0 6px #17654328}}@keyframes work{50%{transform:translateY(-5px)}}
@media(max-width:900px){.shell{grid-template-columns:205px minmax(0,1fr);gap:20px;padding-left:20px;padding-right:20px}.lesson-body{padding:26px 25px 6px}.lesson-header{padding:28px 25px}.challenge{margin:15px 15px 24px;padding:22px 20px}.intro{padding:34px 24px 28px;gap:24px}.intro-note{padding-left:18px}}
@media(max-width:680px){body{font-size:16px}.mast-inner{padding:16px 18px;gap:10px}.brand{font-size:.8rem}.top-actions button{padding:7px 9px;font-size:.73rem}.intro{display:block;padding:28px 20px 24px}.intro h1{font-size:2.6rem;margin-bottom:13px}.intro-note{margin-top:22px;padding:3px 0 3px 16px}.intro-note strong{font-size:1rem;margin-bottom:4px}.intro-note p{font-size:.85rem}.shell{display:block;padding:0 12px 30px}.sidebar{position:static;padding:0 7px 20px}.toc{display:none}.mobile-jump{display:block;margin-top:14px}.mobile-jump label{display:block;font-size:.8rem;margin-bottom:6px}.mobile-jump select{width:100%;padding:11px 9px;border:1px solid #adbdcb;background:#fff;border-radius:9px;font-size:16px}.storage-note{margin:8px 0 0}.lesson-header{padding:24px 22px}.lesson-body{padding:23px 22px 4px}.lesson-body p{font-size:1rem}.challenge{padding:22px 17px;margin:14px 10px 24px}.challenge-header{gap:8px}.badge{font-size:.7rem;padding:4px 8px}.challenge-header h3{font-size:1.18rem}.board{padding:15px 12px}.circuit{grid-template-columns:1fr 22px 1fr;gap:8px}.students{grid-template-columns:repeat(3,1fr)}.lesson-footer{padding:0 16px 22px}.lesson-footer .btn{padding:10px 12px;font-size:.82rem}.footnote{padding:0 22px 28px}.regions{gap:5px}.region{padding:14px 4px}.region span{font-size:.75rem}.team{gap:5px}.finish{margin:0 15px 24px}.order-list li{padding:10px 8px;gap:7px}.order-list .order-text{font-size:.84rem}.order-list button{min-width:36px;min-height:44px}.formula{padding:15px}.example{padding:17px}.sample{gap:6px}.sample button{font-size:.73rem}}
@media(max-width:680px){.sidebar{max-height:none;overflow:visible;padding-right:7px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation:none!important;transition:none!important;scroll-behavior:auto!important}}
@media print{body{background:white;color:#111;font-size:11pt}.masthead,.intro,.shell,.footnote,dialog{display:none!important}.print-book{display:block}.print-book h1{font-size:28pt}.print-book h2{font-size:20pt;break-before:page}.print-book h3{font-size:13pt}.print-book article{padding:0}.print-book .formula,.print-book .example{background:none;border:1px solid #bbb;break-inside:avoid}.print-book p{orphans:3;widows:3}.print-book .print-question{border-top:1px solid #aaa;padding-top:15px}.print-book .print-answer{margin-top:20px;font-size:10pt}@page{margin:18mm}}

.matching{display:grid;gap:14px}.match-row{display:grid;gap:7px;background:white;padding:14px;border:1px solid var(--line);border-radius:10px}.match-row select{width:100%;min-width:0;min-height:46px;padding:9px;border:1px solid #8ba3b8;border-radius:8px;background:white;color:var(--ink)}.notebook-links{max-width:1280px;margin:0 auto;padding:16px 24px;display:flex;gap:18px;flex-wrap:wrap;font-size:.9rem}.reading-reveal{margin:16px 0;padding:14px;border:1px solid var(--line);border-radius:10px}.reading-reveal[open] p{animation:pop .22s ease-out}.word-example mark{background:#ffe6b6;color:#142843;padding:2px 4px;border-radius:3px}.compare-text{display:grid;grid-template-columns:1fr 1fr;gap:12px}.compare-text>p{padding:14px;background:#f1f6fb;border-radius:9px}.punctuation-sample{font-size:1.1rem}.lesson-body details summary{min-height:44px;color:var(--blue);font-weight:600}@media(max-width:480px){.compare-text{grid-template-columns:1fr}.matching select{font-size:16px}}

.word-picks{display:flex;flex-wrap:wrap}.word-picks .option{flex:0 1 auto}.word-picks .key{display:none}.punctuation-sample{margin-top:18px}.punctuation-sample p{margin:10px 0 0;animation:pop .22s ease-out}.punct-mark{color:var(--red);font-weight:800;font-size:1.3em}.punctuation-sample mark{background:#ffe6b6;color:var(--navy)}