:root{--bg:#17191c;--panel:#222529;--raised:#2b2f34;--line:#3b4147;--ink:#f3f5f7;--muted:#a8b0b7;--accent:#38bdf8;--accent-dark:#081e2d;--warning:#7dd3fc;--wrong:#d3dbe4;--header:#17191c;--radius:18px;--font:"Segoe UI",Arial,sans-serif}
*{box-sizing:border-box}html,body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.5 var(--font);min-height:100%}body{overflow-x:hidden}button,input{font:inherit}button,a{touch-action:manipulation;-webkit-tap-highlight-color:transparent}button{cursor:pointer;color:inherit;border:0;background:none}button:disabled{cursor:default;color:#7b8289}a{color:inherit;text-decoration:none}h1,h2,h3,p{margin:0}h1{font-size:30px;line-height:1.2;font-weight:650;letter-spacing:-.6px}h2{font-size:21px;line-height:1.3}h3{font-size:17px}button:focus-visible,a:focus-visible,input:focus-visible,summary:focus-visible{outline:3px solid var(--warning);outline-offset:4px}button:disabled:focus-visible{outline:none}.skip-link{position:fixed;top:-100px;left:12px;background:white;color:#17232d;padding:10px;z-index:1000}.skip-link:focus{top:8px}
.app-header{height:68px;background:var(--header);color:#173350;display:flex;align-items:center;justify-content:space-between;padding:0 max(24px,calc((100% - 1100px)/2));border-bottom:1px solid #c3cfdb}.brand{display:flex;align-items:center;min-height:44px}.brand img{display:block;width:166px;height:auto;background:none;box-shadow:none;border:0;padding:0}.header-action{display:grid;place-items:center;width:44px;height:44px;font-size:25px;color:#2c4657}.header-label{font-size:12px;color:#435c6b;letter-spacing:.2px}.page{max-width:1000px;margin:54px auto 60px;padding:0 24px}.crumb{display:inline-flex;align-items:center;gap:9px;min-height:40px;font-size:13px;color:var(--muted);margin-bottom:16px}.page-title{display:flex;justify-content:space-between;gap:20px;align-items:end;margin-bottom:32px}.page-title p{font-size:14px;color:var(--muted);margin-top:12px}.quiet-tag{font-size:11px;color:var(--muted);white-space:nowrap;letter-spacing:1px;text-transform:uppercase}.class-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.class-card,.chapter-card{border:1px solid var(--line);background:var(--panel);border-radius:var(--radius);text-align:left;position:relative;overflow:hidden}.class-card{min-height:238px;padding:28px;display:flex;flex-direction:column;align-items:flex-start;gap:20px}.class-card .grade{font-size:52px;line-height:1;font-weight:350;color:#c9d4d4;letter-spacing:-2px}.class-card h2{font-size:20px}.card-bottom{width:100%;display:flex;align-items:center;justify-content:space-between;color:var(--muted);font-size:12px;margin-top:auto}.class-card.available,.chapter-card.available{border-color:#aab6c3;background:#172c3d}.class-card.available:before,.chapter-card.available:before{content:"";position:absolute;left:0;top:22px;bottom:22px;width:3px;background:var(--accent);border-radius:0 3px 3px 0}.class-card.available .grade{color:#bae6fd}.card-arrow{font-size:23px;color:var(--accent)}.page-foot{margin-top:28px;font-size:12px;color:var(--muted)}.chapter-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:18px}.chapter-card{padding:26px;min-height:185px;display:grid;grid-template-columns:64px 1fr;column-gap:22px;align-content:center}.chapter-card .chapter-icon{grid-row:1/4}.chapter-card h2{font-size:20px;margin:3px 0 8px}.chapter-card p{font-size:13px;color:var(--muted)}.chapter-card .card-bottom{margin-top:16px}.chapter-icon{height:64px;width:64px;display:grid;place-items:center;color:var(--accent)}.chapter-icon svg{width:60px;height:60px;stroke:currentColor;fill:none;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}.chapter-icon text{fill:currentColor;stroke:none;font-family:Georgia,serif}.chapter-card:not(.available) .chapter-icon{color:#abb2b7}
.journey-page{max-width:680px}.journey-title{margin-bottom:28px}.journey-title h1{font-size:30px}.journey-title p{color:var(--muted);font-size:14px;margin-top:8px}.journey-progress{display:flex;gap:18px;align-items:center;margin:22px 0 26px;font-size:12px;color:var(--muted)}.progress-track{height:7px;background:#3c4246;flex:1;border-radius:8px;overflow:hidden}.progress-track span{display:block;height:100%;background:var(--accent);border-radius:inherit}.journey{list-style:none;padding:0;margin:0 0 26px;position:relative}.journey:before{content:"";position:absolute;left:31px;top:38px;bottom:38px;border-left:1px solid #435769}.journey li+li{margin-top:14px}.journey-node{display:flex;align-items:center;text-align:left;gap:20px;min-height:100px;width:100%;padding:10px 16px 10px 0}.milestone{display:grid;place-items:center;width:64px;height:64px;border:1px solid #63788b;border-radius:20px;background:var(--bg);z-index:1;flex-shrink:0;color:#c3cfdb}.milestone .chapter-icon,.milestone svg{width:37px;height:37px}.journey-node.current .milestone{border:2px solid var(--accent);background:#263d50;color:#c3cfdb}.journey-node.done .milestone{background:var(--accent);color:#172e40;border-color:var(--accent)}.journey-node strong{display:block;font-size:17px;font-weight:600}.journey-node small{display:block;margin-top:5px;font-size:12px;color:var(--muted)}.journey-node:disabled{opacity:.65}.journey-node .node-end{margin-left:auto;font-size:17px;color:var(--muted)}.journey-cta{display:flex;gap:16px;align-items:center}.primary{height:52px;min-height:52px;border-radius:12px;background:var(--accent);color:var(--accent-dark);font-weight:700;border:1px solid #7dd3fc;display:flex;align-items:center;justify-content:center;padding:0 24px}.journey-cta .primary{flex:1}.secondary{border:1px solid var(--line);border-radius:12px;min-height:44px;padding:10px 16px;font-weight:600;font-size:14px}.text-button{font-size:12px;color:var(--muted);min-height:40px;text-decoration:underline;text-underline-offset:3px}
.lesson-top{height:43px;display:flex;gap:18px;align-items:center;max-width:700px;padding:0 24px;margin:auto}.lesson-top .step-count{font-size:12px;color:var(--muted);width:40px;text-align:right}.lesson-shell{max-width:660px;height:calc(100dvh - 111px);min-height:620px;margin:auto;padding:22px 24px 16px;display:grid;grid-template-rows:80px minmax(260px,1fr) 154px;position:relative}.lesson-question h1{font-size:20px;line-height:1.3;letter-spacing:-.3px;font-weight:600}.lesson-question p{font-size:13px;line-height:20px;color:var(--muted);margin-top:9px}.domain{font-size:11px;color:#99a7ac;display:block;margin-top:5px}.arena{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:24px;min-width:0;position:relative;padding:14px 0;overflow:visible}.arena.compact{gap:16px}.formula{font-family:Georgia,"Times New Roman",serif;font-size:36px;line-height:1.3;display:flex;align-items:center;justify-content:center;flex-wrap:wrap;gap:4px;color:#edf2f7;max-width:100%}.formula i,.math-group i{font-style:italic}.formula sup{font-size:.54em;vertical-align:super;line-height:0}.math-dot{padding:0 .12em;color:#c3cfdb}.fraction{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;line-height:1.3;margin:0 .13em}.fraction>span{display:block;padding:3px 6px;white-space:nowrap}.fraction>span:first-child{border-bottom:1.5px solid currentColor}.math-group{white-space:nowrap}.equation-row{display:flex;align-items:center;justify-content:center;gap:14px;flex-wrap:wrap}.blank-power{width:62px;height:48px;background:#262d31;border:1px solid #63788b;border-radius:9px;color:var(--ink);font:24px var(--font);text-align:center;outline-offset:4px;vertical-align:super}.power-entry{display:inline-flex;align-items:flex-start;gap:3px;font:46px Georgia,serif;line-height:1}.power-entry .blank-power{transform:translateY(-7px)}.input-tools{display:flex;gap:14px;align-items:center;justify-content:center}.input-tools button{min-width:52px;min-height:40px;border:1px solid var(--line);border-radius:9px;font-size:16px}.arena-note{font-size:13px;color:var(--muted);line-height:21px;max-width:390px;text-align:center}.mission-intro .formula{font-size:42px}.mission-intro .arena-note{max-width:320px}
.match-grid{display:grid;grid-template-columns:1fr 1fr;gap:12px;width:100%;max-width:440px}.match-column{display:flex;flex-direction:column;gap:12px}.match-btn{position:relative;border:1px solid #50575c;border-radius:12px;min-height:68px;padding:13px 8px;background:#24282d;display:flex;align-items:center;justify-content:center;gap:8px;font:24px Georgia,serif}.match-btn sup{font-size:14px}.match-btn[aria-pressed=true]{outline:2px solid var(--accent);outline-offset:2px;background:#263d50}.pair-tag{position:absolute;top:5px;right:6px;font:10px var(--font);width:16px;height:16px;background:#435769;color:#edf2f7;border-radius:4px;display:grid;place-items:center}.match-btn.paired{border-color:#aab6c3}.matching-note{font-size:12px;color:var(--muted);text-align:center}
.option-list{display:flex;flex-direction:column;gap:10px;width:100%;max-width:460px}.option-list.short{flex-direction:row;gap:12px}.option{display:flex;align-items:center;gap:12px;border:1px solid #50585d;border-radius:12px;min-height:62px;padding:13px 15px;text-align:left;font-size:14px;line-height:21px;background:#24282c}.option-list.short .option{flex:1;justify-content:center;font-size:22px;min-height:64px;padding:10px}.option[aria-pressed=true]{border-color:var(--accent);background:#263d50;box-shadow:inset 0 0 0 1px var(--accent)}.option:disabled{color:inherit}.option-mark{font-size:11px;color:#c3cfdb;width:22px;height:22px;display:grid;place-items:center;border:1px solid #63788b;border-radius:6px;flex-shrink:0}.option .formula{font-size:26px}.option-list.short .option-mark{display:none}.choice-mode .formula{font-size:31px}
.factor-fraction{display:flex;flex-direction:column;align-items:center;gap:10px;min-width:180px}.factor-row{display:flex;gap:8px;align-items:center;justify-content:center;min-height:40px}.factor-row:first-child{border-bottom:1px solid #c3cfdb;padding:0 9px 12px;min-width:100%}.factor{width:40px;height:40px;border:1px solid #63788b;border-radius:9px;background:#263d50;font:24px Georgia,serif;display:grid;place-items:center;color:#edf2f7}.factor[aria-pressed=true]{outline:2px solid var(--warning);outline-offset:2px}.factor.paired{background:#22282a;border-color:#435769;color:#c3cfdb}.pair-evidence{height:23px;font-size:13px;color:var(--accent);text-align:center}.cancel-mode{gap:15px}.cancel-mode .power-entry{font-size:35px}.cancel-mode .blank-power{height:41px;font-size:21px}.cancel-mode .equation-row{gap:10px}
.slider-area{width:100%;max-width:460px;text-align:center}.slider-caption{font-size:12px;color:var(--muted);margin-bottom:18px}.slider-current{font-family:Georgia,serif;font-size:38px;margin:0 0 25px}.power-range{width:100%;accent-color:var(--accent);height:36px;margin:0;cursor:pointer}.scale-labels,.scale-values{display:grid;grid-template-columns:repeat(5,1fr);font-size:15px;gap:0}.scale-values{margin-top:16px;font-size:16px;color:#c3cfdb}.scale-labels>span,.scale-values>span{padding:8px 0;border-radius:8px}.scale-values .active{background:#435769;color:#edf2f7}.intervals{display:grid;grid-template-columns:repeat(4,1fr);padding:0 10%;font-size:11px;color:#aab6c3;margin-top:6px}.slider-note{font-size:11px;color:var(--muted);margin-top:17px}
.expression-mode{gap:10px;justify-content:center}.expression-mode>.formula{font-size:30px;margin-bottom:4px}.expression-editor{width:100%;max-width:460px}.expression-input{width:100%;height:44px;border:1px solid #63788b;border-radius:9px;background:#222b2b;color:var(--ink);padding:8px 12px;font:18px ui-monospace,Consolas,monospace}.input-label{display:block;font-size:11px;color:var(--muted);margin-bottom:5px}.expression-preview{height:64px;display:flex;align-items:center;justify-content:center;color:#c3cfdb;overflow:auto;max-width:100%;font-size:13px}.expression-preview .formula{font-size:22px}.expression-preview .parse-note{font:11px var(--font);color:#b2baba;line-height:16px;text-align:center}.math-keypad{display:grid;grid-template-columns:repeat(7,1fr);gap:5px}.math-key{height:34px;border:1px solid #435769;border-radius:7px;font-size:16px;background:#272f30;color:#edf2f7}.math-key.var{background:#263d50;color:#c3cfdb;font-family:Georgia,serif;font-size:20px}.math-key:active{background:#435769}.editor-syntax{display:block;margin:6px auto 0;font-size:11px;min-height:30px;color:var(--muted);text-decoration:underline;text-underline-offset:3px}
.lesson-footer{display:grid;grid-template-rows:30px 42px 52px;gap:10px;align-content:end;min-width:0}.lesson-utilities{display:flex;justify-content:space-between;align-items:center;font-size:12px;color:var(--muted)}.lesson-utilities button{min-height:32px;padding:4px 0}.lesson-utilities .help-button{color:#c3cfdb}.feedback{display:flex;align-items:center;justify-content:space-between;gap:12px;min-width:0;font-size:12px;line-height:17px}.feedback .status-copy{max-width:430px}.feedback strong{font-size:13px;display:block}.feedback.correct{color:#e6edf5}.feedback.wrong,.feedback.format{color:#e6edf5}.feedback.unsupported{color:#c4cccf}.why{font-size:12px;min-height:38px;padding:8px 12px;border:1px solid #63788b;border-radius:10px;white-space:nowrap}.check{width:100%}.check:disabled{background:#30383a;color:#aab6c3;border-color:#435769}.hint-panel{position:absolute;z-index:8;bottom:171px;left:24px;right:24px;background:#263d50;border:1px solid #63788b;border-radius:16px;padding:16px;box-shadow:0 16px 50px #0005;max-height:310px;overflow:auto}.hint-panel header{display:flex;align-items:center;gap:10px}.hint-panel header strong{font-size:14px;flex:1}.hint-panel header button{height:32px;min-width:32px}.hint-panel p{font-size:14px;line-height:22px;margin:12px 0}.hint-panel .next-hint{font-size:12px;color:#edf2f7;text-decoration:underline;min-height:36px}.hint-panel.minimized .hint-body{display:none}
dialog{background:#262c2e;color:var(--ink);border:1px solid #63788b;border-radius:20px;max-width:500px;width:calc(100% - 36px);padding:25px;max-height:85dvh}dialog::backdrop{background:#0009}dialog h2{font-size:22px;line-height:1.3;margin:8px 26px 18px 0}dialog p{font-size:14px;line-height:23px;color:#c3cfdb}dialog p+p{margin-top:12px}.dialog-close{position:absolute;right:14px;top:14px;width:36px;height:36px;font-size:23px;color:var(--muted)}.dialog-actions{display:flex;gap:12px;margin-top:24px;justify-content:flex-end}.dialog-actions .primary{font-size:14px;min-height:46px;height:46px}.summary-list{padding-left:20px;font-size:13px;line-height:22px;max-height:27vh;overflow:auto;margin-top:18px}.summary-list button{width:100%;padding:7px 0;text-align:left}.summary-list span{float:right;color:var(--accent)}.summary-note{font-size:12px!important;color:var(--muted)!important}.storage-warning{font-size:11px;color:var(--warning);position:fixed;bottom:2px;left:10px;z-index:99}
@media(max-width:700px){.app-header{height:64px;padding:0 20px}.brand img{width:152px}.header-label{font-size:11px}.page{margin:30px auto 40px;padding:0 20px}.page-title{margin-bottom:24px;align-items:start}.page-title h1{font-size:28px}.page-title p{font-size:13px;max-width:230px;margin-top:10px}.quiet-tag{display:none}.class-grid{grid-template-columns:1fr;gap:12px}.class-card{min-height:142px;padding:20px;display:grid;grid-template-columns:64px 1fr;column-gap:20px;row-gap:6px;align-content:center}.class-card .grade{grid-row:1/3;font-size:44px;align-self:center}.class-card h2{font-size:20px}.class-card .card-bottom{margin:0}.page-foot{font-size:11px;margin-top:22px}.crumb{margin-bottom:8px}.chapter-grid{gap:12px}.chapter-card{min-height:186px;padding:19px 16px;display:flex;flex-direction:column;align-items:flex-start;gap:0}.chapter-card .chapter-icon{width:50px;height:50px;margin-bottom:14px}.chapter-card .chapter-icon svg{width:47px;height:47px}.chapter-card h2{font-size:16px;line-height:22px;margin:0 0 6px}.chapter-card p{font-size:11px}.chapter-card .card-bottom{margin-top:auto;padding-top:12px;font-size:11px}.chapter-card .card-arrow{font-size:17px}.journey-title h1{font-size:27px}.journey-title p{font-size:13px}.journey-progress{margin:22px 0 14px}.journey-node{gap:16px;min-height:92px}.journey li+li{margin-top:6px}.journey-node strong{font-size:16px}.journey-node small{font-size:11px;line-height:17px}.journey-cta{gap:10px}.journey-cta .secondary{padding:9px 12px}.lesson-top{height:40px;padding:0 20px;gap:14px}.lesson-shell{height:calc(100dvh - 104px);min-height:640px;grid-template-rows:90px minmax(240px,1fr) 154px;padding:20px 20px 16px}.lesson-question h1{font-size:18px;line-height:25px}.lesson-question p{font-size:12px;line-height:18px;margin-top:7px}.domain{font-size:10px;line-height:16px;margin-top:4px}.arena{padding:10px 0;gap:20px}.formula{font-size:31px}.mission-intro .formula{font-size:36px}.arena-note{font-size:12px;line-height:20px}.match-btn{font-size:21px;min-height:65px}.match-grid{gap:11px}.match-column{gap:11px}.option{font-size:13px;line-height:19px;padding:12px;min-height:61px;gap:9px}.option-mark{width:20px;height:20px;font-size:10px}.option-list{gap:9px}.option .formula{font-size:24px}.choice-mode{gap:16px}.choice-mode>.formula{font-size:27px}.cancel-mode{gap:12px}.factor{width:36px;height:36px;font-size:22px}.factor-row{gap:6px}.pair-evidence{font-size:12px}.blank-power{width:58px;height:45px;font-size:23px}.expression-mode{gap:6px}.expression-mode>.formula{font-size:25px;margin-bottom:2px}.expression-preview{height:57px}.expression-preview .formula{font-size:20px}.math-key{height:32px;font-size:15px}.math-keypad{gap:4px}.editor-syntax{margin-top:3px;font-size:10px;min-height:28px}.expression-input{height:40px;font-size:16px}.input-label{font-size:10px;margin-bottom:4px}.hint-panel{left:20px;right:20px;bottom:171px}.feedback{font-size:11px;line-height:16px}.feedback strong{font-size:12px}.why{font-size:11px;padding:7px 9px}.lesson-utilities{font-size:11px}.slider-current{font-size:34px;margin-bottom:16px}.slider-caption{margin-bottom:15px}.scale-labels,.scale-values{font-size:14px}.slider-note{font-size:10px}.summary-list{max-height:24vh}}
@media(min-width:701px) and (max-height:820px){.lesson-shell{min-height:600px;grid-template-rows:74px minmax(220px,1fr) 144px;padding-top:16px}.lesson-footer{gap:5px}.arena{gap:16px}.hint-panel{bottom:158px}.page{margin-top:32px}}
@media(prefers-reduced-motion:reduce){*{scroll-behavior:auto!important;animation:none!important;transition:none!important}}
.formula{display:inline-block;text-align:center}.formula sup{vertical-align:super;line-height:0}

.lesson-footer{grid-template-rows:30px 48px 52px;gap:7px}

/* Authentic navy logo stays untouched in the compact navigation header.
   Exercise focus mode uses a dark subject header instead of repeating a light logo strip. */
.app-header{height:52px;background:#17191c;border-bottom-color:#555f61}
.brand img{width:138px}
.focus-header{height:44px;background:var(--bg);color:var(--muted);border-bottom:0}
.focus-label{font-size:12px;letter-spacing:.2px;color:#c3cfdb}
.focus-header .header-action{color:#c3cfdb}
.lesson-shell{height:calc(100dvh - 87px)}
.power-entry{font-size:36px;gap:3px}
.power-entry .blank-power{width:46px;height:36px;font-size:20px;transform:translateY(-16px);padding:2px 0}
.cancel-mode .power-entry{font-size:34px}
.cancel-mode .power-entry .blank-power{height:34px;font-size:19px;transform:translateY(-15px)}
@media(max-width:700px){
 .app-header{height:52px}.brand img{width:132px}
 .focus-header{height:44px}
 .lesson-shell{height:calc(100dvh - 84px)}
 .power-entry{font-size:35px}
 .power-entry .blank-power{width:46px;height:35px;font-size:20px;transform:translateY(-16px)}
 .math-key{height:44px}
}
.journey-node:disabled{opacity:1;color:#c3cfdb}.journey-node:disabled .milestone{border-color:#435769;color:#aab6c3}

.match-math{white-space:nowrap}.match-math sup{font-size:.65em;vertical-align:super;line-height:0}

/* LaTeX presentation: use one bundled math family; UI prose stays Segoe UI. */
.math-notation{display:inline-block;max-width:100%;vertical-align:baseline}
.math-notation>.katex{font-size:1em}
.formula{font-family:inherit;line-height:1.55}
.formula .math-notation{max-width:100%}
.math-icon{font-size:31px}
.math-icon .math-notation{line-height:1}
.match-btn{font-family:inherit;font-size:24px}
.match-btn>.math-notation{line-height:1.4}
.factor{font-family:inherit}
.factor>.math-notation{line-height:1}
.power-entry{font-family:inherit;align-items:baseline}
.power-base{font-size:35px;display:inline-flex;line-height:1}
.power-entry .blank-power{position:relative;top:-16px;transform:none;align-self:center}
.equation-row>.formula{line-height:1.9}
.slider-current{font-family:inherit;min-height:70px;line-height:1.8}
.scale-values>span{min-height:47px;display:flex;align-items:center;justify-content:center}
.scale-labels>span .katex,.intervals .katex,.scale-values .katex{font-size:1em}
.math-key{font-family:inherit}.math-key.var{font-family:inherit}
.math-key .math-notation{line-height:1.2;pointer-events:none}
.expression-preview{height:68px;padding:3px 0}
.expression-preview .formula{font-size:20px}
.lesson-question p .math-notation{font-size:1.06em}
.domain .math-notation{font-size:1.04em}
.hint-panel p,.hint-body p,dialog p{line-height:1.8}
.pair-evidence{line-height:1.8}
.status-copy .math-notation{font-size:1em}
@media(max-width:700px){
 .formula{font-size:29px}
 .expression-mode>.formula{font-size:24px}
 .match-btn{font-size:22px}
 .power-base{font-size:34px}
 .option .formula{font-size:23px}
 .slider-current{font-size:30px}
 .math-icon{font-size:29px}
}

/* Approved family: charcoal, neutral gray, soft white, navy and light blue. */
:root{--bg:#17191c;--panel:#22272e;--raised:#2b323c;--line:#3c4652;--ink:#f3f5f7;--muted:#aab4c0;--accent:#38bdf8;--accent-dark:#081e2d;--warning:#7dd3fc;--wrong:#e6edf5;--header:#17191c}
.app-header{background:var(--bg);color:var(--ink);border-bottom:1px solid #2b323a}
.header-label,.focus-label,.header-action{color:var(--muted)}
.class-card.available,.chapter-card.available{background:#172c3d;border-color:#446b8a}
.class-card.available .grade,.card-arrow{color:#bae6fd}
.primary{border-color:#7dd3fc}
.option[aria-pressed=true],.match-btn[aria-pressed=true]{background:#17354a;border-color:#38bdf8}
.factor.paired{background:#1d3546;border-color:#5f849f;color:#c6dceb}
.expression-input{background:#222c35;border-color:#648299}
.math-key{background:#27323c;border-color:#43576a}.math-key.var{background:#193b51;color:#d8f1ff}
.scale-values>span.active{background:#183f58;color:#e3f5ff}
.hint-panel{background:#25313d;border-color:#56758f}
.feedback.correct,.feedback.done,.feedback.wrong,.feedback.format,.feedback.unsupported{color:#e6edf5}
.feedback strong:before{display:inline-grid;place-items:center;width:16px;height:16px;margin-right:6px;border:1px solid currentColor;border-radius:50%;font:11px/1 var(--font);vertical-align:1px}
.feedback.correct strong:before,.feedback.done strong:before{content:"✓"}
.feedback.wrong strong:before{content:"↻"}
.feedback.format strong:before{content:"≈"}
.feedback.unsupported strong:before{content:"!"}
.focus-header{border-bottom:0}

/* Twelve-step content revision: same layout, updated content-sized controls. */
.app-name{font:600 18px var(--font);color:var(--ink);letter-spacing:-.3px}
.match-column:nth-child(2) .match-btn{font-size:18px}
.match-btn.needs-check{border-style:dashed;outline:1px dashed #aab4c0}
.match-check{position:absolute;left:6px;top:5px;font:10px var(--font);color:#edf2f7}
.pair-audit{display:flex;justify-content:center;gap:12px;flex-wrap:wrap}
.cancelled-pair{padding:5px 9px;border:1px solid #435769;border-radius:8px;font-size:13px}
.factor.identity{border:0;background:none;display:grid;place-items:center}
.cancel-mode{gap:10px}.cancel-mode .pair-evidence{font-size:11px}
.cancel-mode .equation-row>.formula{font-size:27px}
.cancel-mode .input-tools button{min-height:36px}
.slider-caption{line-height:1.6;font-size:11px}
.slider-note{line-height:1.6}
.solution-note{font:11px/1.7 var(--font);color:var(--muted)}
.hint-panel .solution-continue{display:block;border:1px solid #648299;padding:9px 12px;border-radius:8px;text-decoration:none;margin-top:10px}
.summary-list small{display:block;font-size:11px;color:var(--muted);margin-top:3px}
.summary-list button{text-align:left}
.feedback.exploring,.feedback.reviewed{color:var(--ink)}
.feedback.exploring strong:before{content:"↔"}
.feedback.reviewed strong:before{content:"i"}
.lesson-shell{grid-template-rows:90px minmax(260px,1fr) 162px}
.lesson-footer{grid-template-rows:30px 56px 52px;gap:8px}
.hint-panel{bottom:179px}
@media(max-width:700px){
 .lesson-shell{grid-template-rows:94px minmax(240px,1fr) 162px}
 .match-column:nth-child(2) .match-btn{font-size:16px}
 .match-btn{min-height:68px}
 .choice-mode .option{font-size:12px;line-height:20px;padding:10px}
 .choice-mode .option-mark{flex-shrink:0}
 .cancel-mode .equation-row>.formula{font-size:24px}
 .slider-current{font-size:28px}
 .lesson-utilities{font-size:10px}
 .lesson-utilities button{white-space:nowrap}
}

.summary-list button{vertical-align:top}
.hint-body .math-notation,dialog p .math-notation{line-height:2.1}

/* Pedagogy revision: immediate input and one active mathematical change. */
.number-entry{width:100%;max-width:284px}
.number-entry-label{display:flex;align-items:baseline;justify-content:space-between;gap:8px;margin-bottom:7px;line-height:18px}
.number-entry-label strong{font-size:12px;font-weight:600}
.number-entry-label span{font-size:10px;color:var(--muted)}
.number-keypad{display:grid;grid-template-columns:repeat(4,1fr);gap:6px}
.number-key{min-width:44px;height:44px;border:1px solid #43576a;border-radius:8px;background:#27323c;font-size:18px}
.number-key:hover{background:#304153}.number-key:active{background:#365068}
.number-key[data-nkey="-"],.number-key[data-nkey="Backspace"]{background:#193b51}
.number-key:disabled{opacity:.48}
.given-anchor{display:flex;align-items:center;gap:14px;color:var(--muted);font-size:11px}
.given-anchor .formula{font-size:21px}
.prediction-anchor{display:flex;align-items:center;justify-content:center;gap:20px;width:100%;max-width:430px}
.prediction-anchor .formula{font-size:25px}
.step-operation{display:flex;align-items:center;flex-direction:column;font-size:14px;color:#bae6fd;gap:3px}
.step-operation>span:last-child{font-size:26px;line-height:20px}
.prediction-caption{font-size:12px;color:var(--muted);text-align:center;margin-top:-12px}
.prediction-mode{gap:22px}
.prediction-question{font-size:30px}
.skip-prediction{font-size:11px;color:var(--muted);text-decoration:underline;min-height:44px;padding:8px}
.editor-instruction{font-size:10px;color:var(--muted);line-height:16px;margin:0 0 6px}
.factor-workspace{display:flex;align-items:center;justify-content:center;gap:14px;max-width:100%}
.factor-workspace .pair-audit{flex-direction:column;gap:6px}
.cancel-mode{gap:6px}
.cancel-mode .factor{width:44px;height:44px}
.cancel-mode .factor-row{min-height:44px}
.cancel-mode .pair-evidence{height:20px;line-height:20px;font-size:10px}
.cancel-mode .number-entry{max-width:284px}
.cancel-mode .equation-row>.formula{font-size:24px}
.cancel-mode .number-entry-label{margin-bottom:4px}
.cancel-mode .number-keypad{gap:5px}
@media(max-width:700px){
 .prediction-anchor{gap:16px}.prediction-anchor .formula{font-size:23px}
 .prediction-mode{gap:19px}
 .cancel-mode .equation-row>.formula{font-size:22px}
 .cancel-mode .power-base{font-size:29px}
 .cancel-mode .power-entry .blank-power{top:-12px;height:34px}
 .factor-workspace{gap:10px}
 .cancelled-pair{padding:4px 7px;font-size:12px}
 .expression-mode>.formula{font-size:23px}
}

.cancel-mode .equation-row{padding-top:20px}

/* r4: semantic feedback remains local; the site palette stays neutral/blue. */
:root{--feedback-correct:#9bceb0;--feedback-wrong:#dea0a8}
.feedback.correct,.feedback.done{border-left:2px solid var(--feedback-correct);padding-left:10px;background:transparent}
.feedback.wrong{border-left:2px solid var(--feedback-wrong);padding-left:10px;background:transparent}
.feedback.correct strong,.feedback.done strong{color:var(--feedback-correct)}
.feedback.wrong strong{color:var(--feedback-wrong)}
.feedback.format,.feedback.unsupported,.feedback.reviewed{border-left:2px solid #648299;padding-left:10px}
.factor-row{gap:4px}
.factor-op{display:inline-flex;align-items:center;justify-content:center;font-size:14px;line-height:1;flex-shrink:0;color:#dbe7ef}
.lesson-question h1{font-size:22px}
.lesson-question p{font-size:14px;line-height:21px}
.choice-mode .option{font-size:15px;line-height:23px}
.multiselect-mode{gap:20px}
.multi-question{font-size:36px}
.multi-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px;width:100%;max-width:430px}
.multi-card{position:relative;min-height:110px;border:1px solid #536675;border-radius:14px;background:#222a32;display:flex;align-items:center;justify-content:center;padding:20px 18px 16px}
.multi-card .formula{font-size:32px}
.multi-check{position:absolute;top:10px;right:10px;width:20px;height:20px;border:1px solid #7b8d9c;border-radius:5px;font:14px/18px var(--font);color:#edf8ff;text-align:center}
.multi-card[aria-checked=true]{border-color:var(--accent);box-shadow:inset 0 0 0 1px var(--accent);background:#19384b}
.multi-card[aria-checked=true] .multi-check{background:#245a77;border-color:#7dd3fc}
.multi-card:disabled{opacity:1;color:var(--ink)}
.multi-instruction{font-size:12px;color:var(--muted);text-align:center;line-height:19px}
.mission-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px}
.mission-card{border:1px solid #42657e;background:#1d2b37;border-radius:18px;padding:25px;display:flex;flex-direction:column}
.mission-card-top{display:flex;align-items:center;justify-content:space-between;color:var(--muted);font-size:12px;margin-bottom:16px}
.mission-card-top .chapter-icon{width:52px;height:52px}
.mission-card h2{font-size:25px;line-height:1.25;margin:0 0 10px}
.mission-card p{font-size:15px;line-height:23px;color:#d0dbe4}
.mission-card .mission-detail{font-size:12px;line-height:19px;color:var(--muted);margin-top:8px}
.mission-progress{height:5px;border-radius:4px;background:#384752;overflow:hidden;margin-top:24px}
.mission-progress>span{display:block;height:100%;background:#72c7ed}
.mission-status{font-size:12px;color:var(--muted);margin:10px 0 18px}
.mission-actions{display:flex;align-items:center;gap:20px;margin-top:auto}
.mission-actions .primary{flex:1;font-size:15px}
.mission-actions .text-button{display:inline-flex;align-items:center;font-size:12px}
.mission-reset{align-self:flex-start;margin-top:12px;min-height:36px;font-size:12px;color:#b5c4d0;text-decoration:underline}
.completion-note{padding:12px 16px;border-left:2px solid #7fbad5;background:#1d2b37;color:#d0dbe4;font-size:14px;line-height:22px;margin-bottom:22px}
.class-card:disabled,.chapter-card:disabled{opacity:.65;cursor:default}
@media(max-width:700px){
 .lesson-shell{grid-template-rows:106px minmax(240px,1fr) 162px}
 .lesson-question h1{font-size:20px;line-height:27px}
 .lesson-question p{font-size:14px;line-height:21px}
 .domain{font-size:11px;line-height:16px}
 .choice-mode .option{font-size:14px;line-height:22px;padding:12px}
 .multiselect-mode{gap:18px}
 .multi-question{font-size:34px}
 .multi-card{min-height:108px;padding:20px 14px 16px}
 .multi-card .formula{font-size:30px}
 .mission-grid{grid-template-columns:1fr;gap:18px}
 .mission-card{padding:22px}
 .mission-card h2{font-size:23px}
 .mission-actions{gap:14px}
 .mission-card-top{margin-bottom:12px}
 .mission-catalog .page-title h1{font-size:27px}
}