:root{--ink:#14263e;--muted:#66748a;--line:#e1e7ed;--teal:#087d71;--mint:#c5f5df;--bg:#f5f7fa;--yellow:#f4cf57}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.6 system-ui,-apple-system,'Segoe UI',sans-serif}button,input{font:inherit}button,a,input{ -webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.55}button:focus-visible,a:focus-visible,input:focus-visible{outline:3px solid #078fbd;outline-offset:4px}header{height:86px;border-bottom:1px solid var(--line);background:#fff;display:flex;align-items:center;gap:30px;padding:0 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#c6d3de;background:#f2f6fa;color:var(--ink);min-width:48px;min-height:43px;border-radius:7px;font:700 18px monospace}.bit.on{background:#c5f5df;border-color:#15816a}.kmap{display:grid;gap:8px;margin:22px auto;max-width:460px;grid-template-columns:48px repeat(4,1fr)}.kmap.two{grid-template-columns:48px repeat(2,1fr);max-width:320px}.kmap>span{text-align:center;font:14px/44px monospace}.kcell{min-height:55px;font:700 22px monospace;border:2px solid var(--line);border-radius:9px;background:white;color:var(--ink)}.kcell.selected{border-color:#098670;background:#c5f5df}.lab-controls{display:flex;gap:15px;flex-wrap:wrap;align-items:center}.select-gates{display:flex;gap:8px;flex-wrap:wrap;margin:20px 0}.select-gates button{padding:9px 15px}.notice{color:var(--muted);font-size:14px}.empty{text-align:center;padding:50px 25px;background:#fff;border:1px solid var(--line);border-radius:14px}.empty h2{font-size:27px}.completion{text-align:center}.completion .big{font-size:55px;color:var(--teal)}.grid-metrics{display:grid;grid-template-columns:repeat(3,1fr);gap:14px}svg{overflow:visible}.sr-only{position:absolute;clip:rect(0,0,0,0);width:1px;height:1px;overflow:hidden}@media(max-width:1050px){main{padding:27px 25px}.app{grid-template-columns:205px 1fr}aside{padding:30px 15px}.hero{padding:25px;grid-template-columns:1fr}.hero .diagram{display:none}.header-label{display:none}.xp{margin-left:auto}}@media(max-width:700px){header{padding:0 18px;height:72px}.brand{font-size:20px}.mark{width:32px;height:32px}.app{display:block}aside{min-height:0;border-right:0;border-bottom:1px solid var(--line);padding:8px 10px;background:white}aside>.eyebrow,.side-note,.storage-note{display:none}nav{margin:0;display:flex;gap:3px;justify-content:space-between}.nav{font-size:14px;padding:10px 8px;justify-content:center;gap:5px;width:auto}.nav small{display:none}.nav span{font-size:12px}main{padding:22px 16px 45px}.page-top h1{font-size:26px}.page-top .pill{display:none}.page-top p{font-size:14px}.hero h2{font-size:26px}.stats{gap:8px;margin:16px 0 23px}.stat{padding:11px 9px}.stat strong{display:block;font-size:22px}.stat span{font-size:12px}.modules{gap:12px;grid-template-columns:1fr}.lesson-card{padding:21px 18px}.lesson-card h2{font-size:23px}.choices{gap:9px}.choice{padding:12px;font-size:15px}.section-top span{font-size:12px}.grid-metrics{grid-template-columns:1fr}.formula{font-size:19px}.lesson-row{padding:16px}.xp{padding:6px 11px}}
/* Expanded learning workspace */
:root{font-size:16px}.nav span{font-size:14px}.notice{line-height:1.65}.hero .diagram-scroll{overflow:visible}.hero-diagram .circuit-diagram{min-width:0;width:100%;max-height:250px}.stage-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:15px}.stage{background:white;border:1px solid var(--line);padding:22px;border-radius:12px;display:flex;flex-direction:column;align-items:flex-start}.stage h2{font-size:20px;line-height:1.4}.stage p{font-size:14px;color:var(--muted);margin-top:auto}.level{display:inline-block;border-radius:20px;padding:3px 10px;font-size:13px;font-weight:700;background:#e6f3ed;color:#21644f;white-space:nowrap}.level-1{background:#e7edfc;color:#365c94}.level-2{background:#fff1d8;color:#865d0a}.exam-card{display:flex;align-items:center;gap:25px;justify-content:space-between;background:#e9eff6;padding:22px;border-radius:12px;margin-top:22px}.exam-card p{font-size:14px;margin:5px 0;color:var(--muted)}.exam-card button{flex-shrink:0}.bank-list{display:grid;gap:10px}.bank-row{display:flex;gap:18px;align-items:center;justify-content:space-between;text-align:left;padding:16px 19px;background:#fff;border:1px solid var(--line);border-radius:10px;color:var(--ink)}.bank-row strong{display:block;font-size:16px;margin-top:7px;font-weight:600}.bank-row:hover{border-color:#59998a}.status-badge{font-size:13px;white-space:nowrap;color:#587062}.question-meta{display:flex;align-items:center;gap:14px}.question-meta .eyebrow{font-size:13px}select{font:inherit;background:#fff;color:var(--ink);border:1px solid #c8d4de;border-radius:7px;min-height:42px;padding:7px 10px;max-width:100%}select:focus-visible{outline:3px solid #078fbd;outline-offset:2px}.section-top label{font-size:14px}.section-top select{margin-left:8px}.symbol-prompt{text-align:center;background:#f5f8fb;border-radius:10px;padding:15px;margin:20px 0}.symbol-prompt .gate-symbol{width:170px;height:120px}.symbol-guide{display:grid;grid-template-columns:repeat(4,1fr);gap:15px;margin-top:20px}.symbol-guide>div{text-align:center;font-size:14px}.symbol-guide .gate-symbol{width:100%;max-width:115px;display:block;margin:auto}.symbol-guide span{display:none}.gate-symbol{width:110px;height:80px}.diagram-scroll{overflow-x:auto;max-width:100%;padding:6px 0;margin:12px 0}.circuit-diagram{display:block;width:100%;min-width:460px;max-height:440px;height:auto}.lesson-card .circuit-diagram{max-height:none}.table-scroll{overflow-x:auto;max-height:620px;margin:15px 0}.truth th{position:sticky;top:0;background:#eef3f8}.truth{margin:15px auto}.kcell{position:relative;padding:7px 4px;display:flex;flex-direction:column;align-items:center;line-height:1.1;min-height:77px}.kcell small{font:12px system-ui;color:#758398;margin-top:3px}.kcell .group-mark{height:14px;font:700 12px system-ui;color:#165f4c;max-width:100%;overflow:hidden}.kcell.grouped{background:#eaf8f0;border-color:#7ab49c}.kcell.selected{border-color:#007a66;background:#bdf0d5;box-shadow:0 0 0 2px #087d71 inset}.group-list{display:flex;gap:8px;flex-wrap:wrap;margin:15px 0}.group-tag{display:flex;gap:8px;align-items:center;border:1px solid #bedbce;background:#eff9f3;padding:7px 10px;border-radius:9px;font-size:14px}.group-tag button{border:0;background:transparent;color:#4b655e;font-size:24px;line-height:1;padding:3px 6px}.gate-builder{display:grid;gap:10px;margin-top:18px}.gate-row{display:grid;grid-template-columns:35px 1.1fr 1fr 1fr 28px;gap:10px;align-items:center;border:1px solid var(--line);padding:12px;background:#f7f9fc;border-radius:10px}.gate-row>strong{font:700 15px monospace}.gate-row label{display:grid;font-size:13px;gap:5px;min-width:0}.gate-row select{width:100%;font-size:15px;padding:6px}.builder-footer{display:flex;align-items:center;justify-content:space-between;gap:20px;margin:17px 0}.builder-footer label{display:flex;align-items:center;gap:10px;font-size:14px}.builder-empty{background:#f3f6fa;border:1px dashed #cbd6df;padding:30px;text-align:center;color:var(--muted);font-size:14px;border-radius:10px}.hint p{margin:7px 0}.solution{background:#eaf4ef}.solution .circuit-diagram{min-width:400px}.result-row{background:white;border:1px solid var(--line);border-radius:10px;margin-bottom:10px;overflow:hidden}.result-row summary{padding:17px;cursor:pointer;display:flex;gap:20px;justify-content:space-between;font-size:15px}.result-row summary>span:last-child{font-size:13px;color:var(--muted);white-space:nowrap}.result-row .hint{margin:0;border-radius:0}.project-brief{background:#e9f2f0;border-left:4px solid #188470;padding:20px;line-height:1.8;border-radius:5px;margin:18px 0}.step-trail{display:flex;gap:10px;flex-wrap:wrap}.step-trail span{padding:8px 14px;background:#e9edf2;border-radius:8px;font-size:14px;color:#637386}.step-trail .current{background:var(--ink);color:white}.lab-symbol{margin:auto}.output-bit{display:inline-block;padding:8px 16px;border-radius:8px;background:var(--mint);font:700 25px monospace}.active-row{background:#e0f3e9;font-weight:700}.lesson-card h2{overflow-wrap:anywhere}.question-meta{flex-wrap:wrap}#main>h1{font-size:30px}.actions .primary{min-width:140px}button{touch-action:manipulation}.hero h2{font-size:29px}#early-start{margin-left:12px}
@media(max-width:1100px){.stage-grid{grid-template-columns:1fr}.stage{display:block}.stage h2{margin:12px 0}.hero-diagram{display:none}.exam-card{align-items:flex-start;flex-direction:column;gap:8px}.gate-row{gap:7px;padding:9px}.bank-row{gap:10px}.status-badge{white-space:normal;max-width:90px}}
@media(max-width:700px){nav{overflow-x:auto;justify-content:flex-start;gap:5px}.nav{flex-shrink:0;min-height:44px}.nav span{font-size:13px}.app aside{padding:7px 8px}main{padding-top:22px}.stage-grid{gap:12px}.stage{padding:18px}.hero{padding:24px}.hero h2{font-size:25px}.section-top{align-items:flex-start;gap:10px}.section-top h2{font-size:20px}.section-top label{display:flex;align-items:center;font-size:13px}.section-top select{max-width:110px;margin-left:4px}.bank-row{padding:14px}.bank-row strong{font-size:15px}.bank-row .status-badge{font-size:12px}.gate-row{grid-template-columns:28px 1fr 1fr 24px;gap:8px;padding:10px}.gate-row>strong{grid-row:1/3}.gate-row label:nth-of-type(1){grid-column:2/4}.gate-row label:nth-of-type(2){grid-column:2;grid-row:2}.gate-row label:nth-of-type(3){grid-column:3;grid-row:2}.gate-row>button,.gate-row>span{grid-column:4;grid-row:1/3}.builder-footer{flex-wrap:wrap;gap:12px}.circuit-diagram{min-width:430px}.question-meta .eyebrow{font-size:12px}.result-row summary{display:block}.result-row summary>span:last-child{display:block;margin-top:8px}.symbol-guide{grid-template-columns:repeat(3,1fr)}.lab-controls{gap:10px}.lab-symbol{margin:0 auto}.lab-symbol .gate-symbol{width:85px}#early-start{margin-left:0;margin-top:12px}.kmap{gap:5px}.kcell{min-height:73px}.project-brief{padding:16px}.actions{gap:14px}.stage p,.exam-card p,.notice{font-size:14px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;transition:none!important}}
/* v4: accessible worked examples, saved drafts and answer review. */
.draft-list,.result-counts{display:flex;gap:10px;flex-wrap:wrap}.result-counts span{background:#edf4f1;border-radius:6px;padding:7px 10px}.result-body{padding:20px}.result-body h3,.result-body h4{margin:8px 0}.solution-detail{margin:18px 0;border:1px solid #b8d6ca;border-radius:8px;overflow:hidden}.solution-detail>summary{display:block;padding:12px;background:#edf7f2;cursor:pointer;color:#165f4c;font-weight:700}.solution-steps,.equation-steps{padding-left:25px;line-height:1.8}.solution-steps li{margin:8px 0;overflow-wrap:anywhere}.equation-steps li{margin:10px 0}.equation-steps code{display:block;font:600 19px ui-monospace,monospace;color:#124a3f;white-space:normal;overflow-wrap:anywhere}.equation-steps span{display:block;color:#52647b;font-size:14px}.solution .truth{background:white}.truth caption{text-align:left;color:#315749;padding:12px 0;font-weight:600}.solution-map td{min-width:62px;height:80px}.solution-map small{display:block;color:#64748b}.solution-map .map-member{background:#ecf7ef}.group-chip{font-size:12px;font-weight:700;border-radius:4px;padding:2px 5px;display:inline-block;margin:2px;color:#132d3b}.group-color-0{background:#b6eacb}.group-color-1{background:#f7d8a6}.group-color-2{background:#bbd9f7}.group-color-3{background:#e2c7f1}.group-color-4{background:#f6c4ce}.group-color-5{background:#dceaa6}.formula{overflow-wrap:anywhere}.bank-row .status-badge{max-width:190px;white-space:normal;text-align:right}.hint .diagram-scroll{background:#fff;border-radius:8px}.hint strong{color:#204738}.result-row .result-body .hint{border-radius:8px}.solution p{overflow-wrap:anywhere}select:focus-visible,summary:focus-visible{outline:3px solid #078fbd;outline-offset:3px}
@media(max-width:700px){.result-body{padding:14px}.result-counts{font-size:13px}.draft-list button{width:100%;text-align:left}.bank-row .status-badge{max-width:115px}.solution-steps{padding-left:20px}.equation-steps code{font-size:17px}}

/* Account screens extend the original visual language. */
[hidden]{display:none!important}.auth-gate{min-height:100vh;display:grid;place-items:center;padding:24px}.auth-card{width:min(100%,480px);margin:0 auto}.auth-card h1{font-size:32px}.auth-card form{display:grid;gap:16px;margin:20px 0}.auth-card label{display:grid;gap:7px}.auth-card input{width:100%;min-width:0;padding:12px;border:1px solid #cdd8df;border-radius:8px;font:inherit}.auth-card .actions{margin-bottom:20px}.auth-card [aria-pressed=true]{border-color:#188975;background:#e1f6ef}.account-bar,.cloud-bar{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:12px 32px;border-bottom:1px solid #e1e6e9;background:#fff}.account-bar details{font-size:12px;overflow-wrap:anywhere}.cloud-bar{font-size:13px;flex-wrap:wrap;background:#f0faf6}.cloud-error{color:#a12a24}.teacher-table{min-width:690px;width:100%}.teacher-table td:first-child{text-align:left}.teacher-table small{display:block}.topic-progress{display:flex;justify-content:space-between;gap:12px;margin-top:16px}.topic-progress small{font-weight:400}#student-detail progress{width:100%;accent-color:#168c76;height:12px}#conflict-actions{display:flex;flex-wrap:wrap;gap:8px}#auth-message{overflow-wrap:anywhere}#learning-area[inert]{opacity:.6;pointer-events:none}@media(max-width:600px){.account-bar,.cloud-bar{padding:12px 16px}.account-bar{align-items:flex-start;flex-direction:column}.auth-gate{padding:16px}.auth-card h1{font-size:28px}}