#challenge{width:min(980px,calc(100vw - 24px));max-width:980px;max-height:92vh;overflow:auto;padding:28px;border-radius:24px}
.task-card{margin:18px 0 14px;padding:16px 18px;border:1px solid rgba(53,231,154,.34);border-radius:16px;background:rgba(53,231,154,.08)}
.task-card span,.answer-label{font-size:.72rem;font-weight:900;letter-spacing:.14em;color:#35e79a}
.task-card h2{margin:6px 0 0;font-size:1.05rem;line-height:1.5}
.case-study{overflow:hidden;border:1px solid rgba(150,177,218,.38);border-radius:17px;background:#f8fbff;color:#142039;box-shadow:0 14px 38px rgba(0,0,0,.14)}
.case-title{display:flex;gap:12px;align-items:center;justify-content:space-between;padding:12px 16px;background:linear-gradient(90deg,#eaf8ef,#edf5ff);border-bottom:1px solid #cbd9e8}
.case-title span{font-size:.72rem;font-weight:900;color:#138c4d;letter-spacing:.11em}.case-title strong{font-size:.92rem;text-align:right}
.sheet-toolbar{display:flex;align-items:center;gap:7px;padding:8px 12px;background:#f4f8fc;border-bottom:1px solid #d4deea}.sheet-toolbar button{display:grid;place-items:center;min-width:34px;height:30px;padding:0 9px;border:1px solid #bfcede;border-radius:8px;background:#fff;color:#173050;font-size:18px;font-weight:900;cursor:pointer}.sheet-toolbar .fit-sheet{width:auto;font-size:12px}.sheet-toolbar .expand-sheet{font-size:15px}.sheet-toolbar b{min-width:58px;text-align:center;color:#173050;font-size:11px}.sheet-toolbar small{margin-left:auto;color:#62728a;font-size:10px}.sheet-scroll{max-width:100%;min-height:70px;overflow:auto;overscroll-behavior:contain;-webkit-overflow-scrolling:touch;touch-action:pan-x pan-y}.sheet-canvas{position:relative;min-width:1px;min-height:1px}.case-sheet{position:absolute;left:0;top:0;width:100%;min-width:max(420px,calc(var(--sheet-cols,4) * 120px));border-collapse:collapse;table-layout:fixed;font-size:.88rem;transform-origin:top left;will-change:transform}
.case-sheet th,.case-sheet td{padding:10px 12px;border-right:1px solid #cad8e6;border-bottom:1px solid #cad8e6;text-align:center;white-space:normal;overflow-wrap:anywhere}
.case-sheet thead th,.case-sheet tbody th{width:48px;background:#edf2f7;color:#173050;font-weight:800}.case-sheet thead th:not(.sheet-corner){width:auto;background:#e6f0eb}
.case-sheet td{background:#fff}.case-sheet td.sheet-heading{background:#f1f7ff;font-weight:800;color:#0e4e93}.case-sheet tr:last-child>*{border-bottom:0}.case-sheet tr>*:last-child{border-right:0}
.answer-workspace{margin-top:16px;padding:16px;border:1px solid rgba(141,158,205,.3);border-radius:16px;background:rgba(255,255,255,.04)}
.answer-label{display:block;margin-bottom:10px}.formula-bar{display:flex;align-items:center;overflow:hidden;border:2px solid #20b660;border-radius:13px;background:#fff}
.formula-bar .fx{align-self:stretch;display:grid;place-items:center;min-width:54px;background:#e9f7ef;color:#138c4d;font-style:italic;font-weight:900;border-right:1px solid #c6dfd0}
.formula-bar .formula-input{margin:0;border:0!important;border-radius:0;background:#fff!important;color:#15213a!important;font-family:ui-monospace,SFMono-Regular,Consolas,monospace;box-shadow:none!important}
.case-options{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px}.case-options .option{text-align:left;margin:0;min-height:50px}
.case-actions{display:flex;gap:10px;flex-wrap:wrap;margin-top:14px}.case-actions button{border:0;border-radius:12px;padding:12px 18px;font-weight:850;cursor:pointer}.hint-btn{background:#fff0d4;color:#8b5700}.skip-btn{background:#e4f1ff;color:#07599a}
html[data-theme=light] .answer-workspace{background:#fff;border-color:#d4dfec}html[data-theme=light] .task-card{color:#15213a}.feedback{margin-top:16px}
@media(max-width:650px){#challenge{width:calc(100vw - 12px);max-height:96dvh;padding:16px 10px;border-radius:18px}.case-title{align-items:flex-start;flex-direction:column;padding:10px 12px}.case-title strong{text-align:left}.sheet-toolbar{padding:7px 9px}.sheet-toolbar small{display:none}.case-options{grid-template-columns:1fr}.case-actions{gap:7px}.case-actions button{flex:1;padding:11px 8px}.case-sheet{font-size:.8rem}.case-sheet th,.case-sheet td{padding:8px}.answer-workspace{padding:12px}.formula-bar .fx{min-width:42px}.formula-bar .formula-input{min-width:0;padding:12px 10px;font-size:14px}}
.switch-participant{margin-top:10px;padding:7px 11px;border:1px solid var(--line);border-radius:9px;background:#ffffff0a;color:var(--muted);font-size:.75rem;font-weight:750;cursor:pointer}.switch-participant:hover{border-color:var(--cyan);color:var(--cyan)}
.case-study.sheet-expanded{position:fixed;inset:0;z-index:9999;display:flex;flex-direction:column;border:0;border-radius:0}.sheet-expanded .case-title{flex:0 0 auto}.sheet-expanded .sheet-toolbar{flex:0 0 auto;padding:10px 14px}.sheet-expanded .sheet-scroll{flex:1;max-height:none;background:#eef4fa}.sheet-view-open{overflow:hidden}