:root{--ink:#192e3d;--muted:#5f707c;--line:#dce4e8;--teal:#22655d;--tint:#eaf3ef;--paper:#fff;--background:#f4f6f4;font:16px/1.6 system-ui,-apple-system,"Segoe UI","Noto Sans CJK SC",sans-serif;color:var(--ink);background:var(--background)}
*{box-sizing:border-box}body{margin:0}button,input,textarea{font:inherit}button,a,input,textarea{-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}button{cursor:pointer}button,.photo-picker{min-height:44px;border-radius:10px;padding:10px 16px;font-weight:600;border:1px solid var(--line);background:var(--paper);color:var(--ink)}button:disabled{opacity:.4;cursor:default}button:focus-visible,a:focus-visible,textarea:focus-visible,.photo-picker:focus-within{outline:3px solid #5d9eda;outline-offset:3px}button.primary{background:var(--teal);border-color:var(--teal);color:white}button.quiet:hover{background:#eff4f1}a{color:var(--teal)}[hidden]{display:none!important}p{margin:0 0 14px}h1,h2,h3{line-height:1.35;margin:0}h1{font-size:clamp(23px,5vw,32px);letter-spacing:-.04em}h2{font-size:20px}h3{font-size:17px}.muted,.source,.submit-note{color:var(--muted);font-size:13px}.topbar{position:sticky;top:0;z-index:8;background:rgba(250,252,250,.97);border-bottom:1px solid var(--line)}.topbar-inner{max-width:1224px;padding:14px 24px 12px;margin:auto;display:flex;justify-content:space-between;align-items:center;gap:12px}.preview-label{font-size:11px;letter-spacing:.07em;color:var(--teal)}.brand{font-size:16px;font-weight:700;margin:3px 0 0}.brand span{font-weight:400;color:var(--muted)}.context{border-top:1px solid #e9eeeb;max-width:1176px;margin:auto;padding:8px 24px;font-size:13px;display:flex;gap:10px;align-items:center;flex-wrap:wrap}.context strong{font-size:14px}.context .question-id{margin-left:auto;color:var(--muted);font-size:11px}main{max-width:1224px;margin:auto;padding:28px 24px 60px}.catalog-intro{padding:24px 0 22px}.eyebrow{text-transform:uppercase;font-size:12px;letter-spacing:.12em;color:var(--teal);margin-bottom:12px}.catalog-intro h1{margin-bottom:12px}.modules{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px}.module-card{padding:22px;text-align:left;display:flex;flex-direction:column;gap:10px;min-height:146px;box-shadow:0 3px 10px #193c2e04}.module-card:first-child{grid-column:1/-1;background:#e9f1ec;border-color:#c6dcd0}.module-card.active{outline:2px solid var(--teal);outline-offset:2px}.module-card strong{font-size:20px;line-height:1.4}.module-card .module-count{color:var(--muted);font-size:13px;font-weight:400}.module-card .module-action{font-size:13px;color:var(--teal);margin-top:auto}.record-list{margin-top:32px}.list-heading{display:flex;align-items:center;justify-content:space-between;gap:12px;margin-bottom:14px}.record-row{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;width:100%;margin:10px 0;padding:16px 18px;text-align:left;gap:12px;font-weight:400}.record-row strong{font-size:16px;display:block}.record-row small{display:block;color:var(--muted);font-size:12px;margin-top:3px}.record-status{font-size:12px;color:var(--muted);white-space:nowrap}.record-status.started{color:var(--teal)}.section-nav{display:flex;align-items:center;gap:12px;margin:-10px 0 18px}.section-nav a{min-height:44px;display:flex;align-items:center;padding:8px 16px;background:white;border:1px solid var(--line);border-radius:24px;text-decoration:none;font-size:14px}.section-nav span{margin-left:auto;color:var(--muted);font-size:12px}.practice-grid{display:grid;gap:20px;align-items:start}.paper,.answer-panel{background:white;border:1px solid var(--line);border-radius:16px;padding:24px;min-width:0;scroll-margin-top:175px}.panel-heading{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-bottom:14px}.paper h1{font-size:21px}.source{font-size:12px;line-height:1.7}.selection-note{font-size:13px;border-left:3px solid var(--teal);background:var(--tint);padding:10px 12px}.image-button{border:0;border-radius:0;background:white;width:100%;padding:4px 0 10px;display:block}.image-button img{display:block;width:100%;height:auto}.image-button small{display:block;color:var(--muted);text-align:right;padding-top:8px;font-weight:400}.image-load-error{color:#9c3d26;background:#fff5ee;padding:12px;font-size:13px}.save-state{font-size:12px;color:var(--teal);font-weight:400}.save-state.failed{color:#a13a27}.choice-question{border:0;padding:0;margin:0 0 24px;min-width:0}.choice-question legend{font-weight:600;font-size:16px;margin-bottom:10px}.choice-hint{font-weight:400;font-size:12px;color:var(--muted);margin-left:8px}.choices{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:10px}.choice{position:relative;display:flex;align-items:center;justify-content:center;border:1px solid var(--line);border-radius:10px;min-height:54px;cursor:pointer;font-size:18px;font-weight:600;gap:8px}.choice:has(input:checked){background:var(--tint);border:2px solid var(--teal);color:var(--teal)}.choice input{margin:0;width:17px;height:17px;accent-color:var(--teal)}.clear-choice{display:block;margin-top:8px;padding:6px 0;border:0;border-radius:0;font-size:12px;font-weight:400;min-height:44px;color:var(--muted)}.field-label{display:block;font-weight:600;margin-bottom:12px}textarea{resize:vertical;width:100%;min-height:240px;border:1px solid #c9d6cf;border-radius:10px;padding:14px;line-height:1.8;color:var(--ink);background:#fcfdfb}textarea::placeholder{color:#7b8982;font-size:14px}.photo-actions{display:flex;align-items:center;gap:12px;flex-wrap:wrap;margin-top:12px}.photo-picker{display:inline-flex;position:relative;align-items:center;cursor:pointer;font-size:14px;overflow:hidden}.photo-picker input{position:absolute;opacity:0;inset:0;width:100%;cursor:pointer}#photo-status{margin:8px 0;font-size:12px}.photo-list{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.photo-card{min-width:0;padding:8px;background:#f4f7f3;border:1px solid var(--line);border-radius:10px}.photo-card img{width:100%;height:128px;object-fit:contain;background:white}.photo-card button{width:100%;font-size:12px;margin-top:4px}.photo-card small{display:block;font-size:11px;overflow:hidden;white-space:nowrap;text-overflow:ellipsis}.submit{width:100%;margin-top:12px}.submit-note{text-align:center;font-size:12px;margin-top:6px;margin-bottom:0}.pending{margin-top:20px;border-top:1px solid var(--line);padding-top:20px}.pending h3{color:var(--teal);margin-bottom:10px}.pending p{font-size:14px;color:var(--muted)}#answer-progress{margin-top:16px;margin-bottom:0}.question-navigation{display:flex;justify-content:space-between;gap:8px;margin-top:24px}.question-navigation button{font-size:13px;padding:10px 14px}.error{padding:16px;background:#fff0e9;color:#8b3321;border:1px solid #edcfc3;border-radius:10px;margin-top:20px}dialog{border:0;border-radius:14px;padding:0;width:calc(100vw - 24px);max-width:1280px;max-height:94dvh;background:#f2f4f1;overflow:hidden}dialog::backdrop{background:#152a38b0}.viewer-toolbar{display:flex;align-items:center;gap:8px;padding:12px;background:white;border-bottom:1px solid var(--line);flex-wrap:wrap}.viewer-toolbar h2{font-size:15px;margin-right:auto}.viewer-toolbar button{padding:8px 14px}.viewer-toolbar span{font-size:12px;min-width:34px;text-align:center}.image-scroll{overflow:auto;max-height:calc(94dvh - 86px);padding:12px;overscroll-behavior:contain}.image-scroll img{display:block;max-width:none;height:auto;margin:auto}.image-scroll img.fit{width:100%}
@media(min-width:900px){.practice-grid{grid-template-columns:minmax(0,1.15fr) minmax(0,1fr)}.modules{grid-template-columns:repeat(4,minmax(0,1fr))}.module-card:first-child{grid-column:1/-1}.question-navigation{padding-left:2px;padding-right:2px}}
@media(max-width:540px){main{padding:20px 14px 40px}.topbar-inner{padding:11px 16px}.brand{font-size:15px}.topbar-inner button{font-size:12px;padding:8px 12px}.context{padding:8px 16px;gap:5px 10px}.context .question-id{font-size:10px}.catalog-intro{padding:15px 3px 22px}.modules{gap:10px}.module-card{padding:17px 14px;min-height:142px}.module-card strong{font-size:17px}.paper,.answer-panel{padding:18px 16px;border-radius:12px}.panel-heading{align-items:baseline;flex-wrap:wrap;gap:5px}.record-row{padding:14px}.record-row strong{font-size:14px}.section-nav{gap:6px}.section-nav a{font-size:13px;padding:8px 14px}.section-nav span{font-size:11px}.question-navigation button{font-size:12px;padding:10px}.choice{min-height:54px;gap:5px}.choices{gap:7px}.source{font-size:11px}.viewer-toolbar{gap:5px}.viewer-toolbar button{padding:8px 12px}.viewer-toolbar h2{width:100%;font-size:13px}}
@media(prefers-reduced-motion:no-preference){html{scroll-behavior:smooth}}
.ai-text{white-space:pre-wrap;overflow-wrap:anywhere;font-size:15px;line-height:1.85}.attempt-card{border-top:1px solid var(--line);margin-top:20px;padding-top:20px}.attempt-card h3{margin-bottom:10px}.result-item{background:var(--tint);border-radius:10px;padding:12px;margin:12px 0}.result-item p:last-child{margin-bottom:0}.support-actions{display:flex;gap:8px;flex-wrap:wrap;margin:14px 0}.attempt-card textarea{min-height:90px;margin:8px 0}.login-shell{max-width:500px;padding-top:12vh}.login-shell h1{font-size:25px;margin-bottom:24px}input:not([type=radio]):not([type=checkbox]):not([type=file]),select{width:100%;padding:12px;border:1px solid #c9d6cf;border-radius:8px;color:var(--ink);background:white;font:inherit;min-height:46px}.teacher-shell{max-width:900px;display:grid;gap:20px}.settings-form{display:grid;gap:14px;margin:20px 0}.settings-form label{font-size:14px;font-weight:600;display:grid;gap:6px}.invite-card{border-top:1px solid var(--line);padding:16px 0;overflow-wrap:anywhere}.invite-card a{display:block;margin:8px 0}.invite-card button{margin-right:8px}.success{background:var(--tint);padding:14px;border-radius:10px;color:var(--teal)}
/* Match the question-reader AI typography; constrain math and diagrams to the answer panel. */
.pb-ai-markdown{white-space:normal;line-height:1.9;overflow-wrap:anywhere;min-width:0;max-width:100%;font-size:15px;color:var(--ink)}.pb-ai-markdown p{margin:.7em 0;font-size:inherit;color:inherit}.pb-ai-markdown h3,.pb-ai-markdown h4,.pb-ai-markdown h5,.pb-ai-markdown h6{margin:1.1em 0 .45em;font-size:1.05em;line-height:1.6}.pb-ai-markdown h3{padding-top:12px;border-top:1px solid var(--line);margin-top:26px}.pb-ai-markdown h3:first-child{border-top:0;padding-top:0;margin-top:12px}.pb-ai-markdown ul,.pb-ai-markdown ol{padding-left:1.7em;margin:.6em 0}.pb-ai-markdown li{margin:.35em 0}.pb-ai-markdown pre{white-space:pre-wrap;overflow-wrap:anywhere;max-width:100%;padding:10px;background:#f4f6f5;border-radius:6px}.pb-ai-markdown code{font-family:monospace}.pb-ai-markdown .katex{font-size:1.1em}.pb-ai-markdown .pb-math-source:has(.katex-display),.pb-ai-markdown .qw-math-display{display:block;overflow-x:auto;max-width:100%;padding:4px 0}.pb-ai-markdown .katex-display{margin:0;padding:2px;text-align:left}.attempt-card,.result-item{min-width:0;max-width:100%}.pb-ai-markdown .pb-ai-diagram{max-width:100%;overflow:hidden}.pb-ai-markdown>p:first-child{margin-top:0}