:root{--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light;--surface-primary:#f7f8fa;--surface-secondary:#fff;--surface-elevated:#fff;--text-primary:#171a1d;--text-secondary:#5f6872;--text-tertiary:#8d98a3;--border-default:#dce2e8;--border-subtle:#ecf0f3;--accent-primary:#0f766e;--accent-hover:#115e59;--status-success:#15803d;--status-warning:#b45309;--status-error:#b91c1c;--status-info:#2563eb;--space-1:4px;--space-2:8px;--space-3:12px;--space-4:16px;--space-5:20px;--space-6:24px;--space-8:32px;--space-10:40px}*{box-sizing:border-box}html{background:var(--surface-primary);min-height:100%}body{min-height:100dvh;color:var(--text-primary);background:var(--surface-primary);margin:0;font-family:ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}button{font:inherit}a{color:var(--status-info)}.shell{width:min(1120px,100%);padding:var(--space-8);margin:0 auto}.seat-surface{gap:var(--space-8);border:1px solid var(--border-default);background:var(--surface-secondary);border-radius:8px;grid-template-columns:minmax(220px,280px) minmax(0,1fr);min-height:calc(100dvh - 64px);display:grid;overflow:hidden}.seat-rail{gap:var(--space-6);min-height:0;padding:var(--space-6);border-right:1px solid var(--border-subtle);background:color-mix(in srgb, var(--surface-primary) 58%, var(--surface-secondary));flex-direction:column;display:flex}.seat-code{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;font-size:40px;font-weight:700;line-height:1.1}.caption{margin:0 0 var(--space-2);color:var(--text-tertiary);letter-spacing:.04em;text-transform:uppercase;font-size:12px;font-weight:650}.student-name{margin:0;font-size:24px;font-weight:700}.worksheet-list{align-content:start;gap:var(--space-2);min-height:0;max-height:min(360px,100dvh - 260px);padding-right:var(--space-1);display:grid;overflow-y:auto}.worksheet-list .caption{grid-column:1/-1}.worksheet-tab{gap:var(--space-1);width:100%;min-height:68px;padding:var(--space-3);border:1px solid var(--border-subtle);color:var(--text-primary);background:var(--surface-secondary);cursor:pointer;text-align:left;border-radius:8px;transition:transform .12s ease-out,border-color .12s ease-out,background-color .12s ease-out;display:grid}.worksheet-tab span:first-child{font-size:15px;font-weight:700;line-height:1.35}.worksheet-tab span:last-child{color:var(--text-secondary);font-size:13px;line-height:1.4}.worksheet-tab:hover{border-color:var(--accent-primary)}.worksheet-tab:active{transform:translateY(1px)}.worksheet-tab[data-selected=true]{border-color:var(--accent-primary);background:color-mix(in srgb, var(--accent-primary) 10%, var(--surface-secondary))}.worksheet-tab[data-selected=true] span:first-child{color:var(--accent-primary)}.seat-main{gap:var(--space-6);min-width:0;min-height:0;padding:var(--space-6);flex-direction:column;display:flex}.page-title{margin:0;font-size:30px;line-height:1.2}.meta-row{gap:var(--space-2);margin-top:var(--space-3);color:var(--text-secondary);flex-wrap:wrap;font-size:14px;display:flex}.problem-grid{gap:var(--space-3);grid-template-columns:repeat(5,minmax(72px,1fr));display:grid}.problem-button{border:1px solid var(--border-default);min-height:64px;color:var(--text-primary);background:var(--surface-elevated);cursor:pointer;border-radius:8px;font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;font-size:20px;font-weight:700;transition:transform .12s ease-out,background-color .12s ease-out,color .12s ease-out}.problem-button:hover{border-color:var(--accent-primary)}.problem-button:active{transform:translateY(1px)}.problem-button:focus-visible,.worksheet-tab:focus-visible,.submit-button:focus-visible,.history-delete-button:focus-visible{outline:3px solid color-mix(in srgb, var(--accent-primary) 35%, transparent);outline-offset:2px}.problem-button[data-selected=true]{border-color:var(--accent-primary);color:var(--surface-secondary);background:var(--accent-primary)}.submit-row{justify-content:space-between;align-items:center;gap:var(--space-4);padding:var(--space-4);border:1px solid var(--border-subtle);background:var(--surface-elevated);border-radius:8px;display:flex}.submit-button{border:1px solid var(--accent-primary);min-width:132px;min-height:48px;color:var(--surface-secondary);background:var(--accent-primary);cursor:pointer;border-radius:8px;font-weight:700;transition:transform .12s ease-out,background-color .12s ease-out}.submit-button:hover{background:var(--accent-hover)}.submit-button:active{transform:translateY(1px)}.submit-button:disabled{border-color:var(--border-default);color:var(--text-tertiary);background:var(--border-subtle);cursor:not-allowed}.status-panel{min-height:0;padding:var(--space-5);border:1px solid var(--border-subtle);background:var(--surface-elevated);border-radius:8px}.status-panel h2{margin:0 0 var(--space-3);font-size:18px}.history-list{gap:var(--space-3);max-height:min(360px,38dvh);margin:var(--space-4) 0 0;padding:0;padding-right:var(--space-1);list-style:none;display:grid;overflow-y:auto}.history-list li{align-items:center;gap:var(--space-4);padding-top:var(--space-3);border-top:1px solid var(--border-subtle);color:var(--text-secondary);grid-template-columns:minmax(0,1fr) auto auto;font-size:14px;display:grid}.history-main{gap:var(--space-2);flex-wrap:wrap;align-items:center;min-width:0;display:inline-flex}.history-result{color:var(--text-primary);white-space:nowrap;font-weight:650}.history-source{min-width:52px;padding:2px var(--space-2);border:1px solid var(--border-default);color:var(--text-primary);background:var(--surface-primary);text-align:center;border-radius:6px;font-size:12px;font-weight:700}.history-delete-button{min-width:58px;min-height:34px;padding:var(--space-1) var(--space-2);border:1px solid var(--border-default);color:var(--text-secondary);background:var(--surface-secondary);cursor:pointer;border-radius:6px;font-size:13px;font-weight:650;transition:transform .12s ease-out,border-color .12s ease-out,color .12s ease-out}.history-delete-button:hover{border-color:var(--status-error);color:var(--status-error)}.history-delete-button:active{transform:translateY(1px)}.history-delete-button:disabled{color:var(--text-tertiary);background:var(--border-subtle);cursor:not-allowed}.notice{max-width:720px;margin:var(--space-10) auto;padding:var(--space-6);border:1px solid var(--border-default);background:var(--surface-secondary);border-radius:8px}.notice h1{margin:0 0 var(--space-4);font-size:30px}.notice p{color:var(--text-secondary);line-height:1.6}@media (max-width:760px){.shell{padding:var(--space-4)}.seat-surface{grid-template-columns:1fr}.seat-rail{border-right:0;border-bottom:1px solid var(--border-subtle)}.worksheet-list{grid-template-columns:repeat(2,minmax(0,1fr));max-height:260px}.problem-grid{grid-template-columns:repeat(4,minmax(64px,1fr))}.submit-row{flex-direction:column;align-items:stretch}.history-list{max-height:300px}.history-list li{grid-template-columns:minmax(0,1fr) auto}.history-main{grid-column:1/-1}.history-result{justify-self:start}}