:root{--primary:#4f6ef2;--primary-dark:#3b55d9;--bg:#f4f6fb;--card:#fff;--text:#2b2f3a;--muted:#7a8194;--border:#e3e7f0;--correct:#1fb56d;--correct-bg:#e8f8f0;--wrong:#e5484d;--wrong-bg:#fdeeef;--safe-top:env(safe-area-inset-top,0px);--safe-bottom:env(safe-area-inset-bottom,0px)}*{box-sizing:border-box;margin:0;padding:0}html{-webkit-text-size-adjust:100%}body{background:var(--bg);color:var(--text);-webkit-tap-highlight-color:transparent;overflow-wrap:break-word;min-height:100vh;font-family:Microsoft YaHei,PingFang SC,Segoe UI,sans-serif}.btn,.chip,.opt,.nav-item,.sheet-close,.tool-btn,.header-btn{touch-action:manipulation;-webkit-user-select:none;user-select:none}.header{color:#fff;padding:calc(22px + var(--safe-top,0px))24px 22px;display:flex;background:linear-gradient(135deg,#4f6ef2,#7a5af0);justify-content:space-between;align-items: center;gap:12px;box-shadow:0 2px 10px #4f6ef240}.header-text{min-width:0}.header h1{margin-bottom:4px;font-size:20px}.header 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center;gap:18px;margin-top:16px;padding:16px 20px;box-shadow:0 1px 4px #141e3c0f}.info-bar .subject{font-size:17px;font-weight:700}.info-bar .stat{color:var(--muted);font-size:13px}.info-bar .stat b{color:var(--text);font-size:15px}.filter-bar{background:var(--card);border-radius:14px;margin-top:12px;padding:14px 20px;box-shadow:0 1px 4px #141e3c0f}.filter-row{display:flex;flex-wrap:wrap;align-items: center;gap:8px}.filter-row .label{color:var(--muted);margin-right:4px;font-size:13px}.filter-footer{display:flex;justify-content:flex-end;margin-top:12px}.chapter-chips{display:flex;overflow-y:auto;overscroll-behavior:contain;-webkit-overflow-scrolling:touch;flex-wrap:wrap;gap:8px;max-height:180px}.type-chips{display:flex;flex-wrap:wrap;gap:8px}.collapse-toggle{display:flex;cursor:pointer;color:var(--text);touch-action:manipulation;background:0 0;border:none;align-items: center;gap:10px;width:100%;padding:2px 0;font-family:inherit;font-size:14px}.collapse-toggle:active{opacity:.7}.collapse-title{flex-shrink:0;font-weight:700}.collapse-toggle .summary{text-align:right;color:var(--muted);white-space:nowrap;overflow:hidden;text-overflow:ellipsis;flex:1;min-width:0;font-size:12.5px;font-weight:400}.collapse-toggle .arrow{color:var(--muted);flex-shrink:0;transition:transform .2s;font-size:12px}.filter-bar.open .arrow,.nav-bar.open .arrow{transform:rotate(180deg)}.collapse-body{display:none;margin-top:12px}.filter-bar.open .collapse-body,.nav-bar.open .collapse-body{display:block}.chip{border:1px solid var(--border);color:var(--text);cursor:pointer;background:#fff;border-radius:999px;padding:5px 12px;transition:all .15s;font-size:13px}.chip.active{background:var(--primary);border-color:var(--primary);color:#fff}.progress-wrap{background:var(--card);border-radius:14px;margin-top:16px;padding:14px 20px;box-shadow:0 1px 4px 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.btn:hover{background:var(--primary-dark)}.chip:hover{border-color:var(--primary);color:var(--primary)}.opt:hover{border-color:var(--primary);background:#f8faff}.btn.primary:hover{background:var(--primary-dark)}.btn.secondary:hover{background:#e0e4ef}.nav-item:hover{border-color:var(--primary);color:var(--primary)}.header-btn:hover{background:#ffffff40}}.action-bar{display:none;position:fixed;z-index:10;background:var(--card);padding:8px 10px calc(8px + var(--safe-bottom,0px));align-items:stretch;gap:8px;bottom:0;left:0;right:0;box-shadow:0 -2px 16px #141e3c1a}.tool-btn{display:flex;color:var(--text);cursor:pointer;background:#f0f2f8;border:none;border-radius:10px;flex-direction:column;flex:none;justify-content:center;align-items: center;gap:3px;min-width:60px;font-family:inherit;font-size:11px}.tool-btn .icon{font-size:17px;line-height:1}.tool-btn.active{background:var(--primary);color:#fff}.action-bar .actions{flex:1;gap:8px;margin:0}.action-bar .actions .btn{flex:1;min-height:48px;padding:12px 8px;font-size:14.5px}.action-bar:not(:has(.actions)){justify-content:center}.action-bar:not(:has(.actions)) .tool-btn{flex:1;max-width:150px}@media (max-width:640px){html,body{overflow:hidden;overscroll-behavior:none}body{height:var(--app-height,100dvh);min-height:0}#root{display:flex;flex-direction:column;height:100%}.header{padding:calc(10px + var(--safe-top,0px))16px 10px;flex-shrink:0}.header h1{margin-bottom:2px;font-size:17px}.header .sub{font-size:11.5px}.container{overflow-y:auto;-webkit-overflow-scrolling:touch;overscroll-behavior-y:contain;display:flex;padding:10px 12px calc(92px + var(--safe-bottom,0px));flex-direction:column;flex:1;min-height:0}.progress-wrap{position:sticky;z-index:5;order:0;margin-top:0;top:0}.question-card{order:1}.info-bar{order:4}.container.welcome{padding-bottom:10px}.container.welcome .upload-card{margin:auto 0}.upload-card{border-radius:12px;padding:36px 16px}.upload-card .icon{font-size:36px}.upload-card .btn{padding:12px 24px}.info-bar{border-radius:12px;gap:6px 12px;padding:10px 14px}.info-bar .subject{font-size:15px}.info-bar .stat{font-size:12px}.info-bar .stat b{font-size:13px}.chip{padding:8px 14px}.sheet-panel .chapter-chips,.sheet-panel .nav-grid{overflow:visible;max-height:none}.sheet-panel .filter-footer{margin-top:14px}.sheet-panel .filter-footer .btn{width:100%;min-height:44px}.sheet-panel .nav-item{border-radius:9px;width:38px;height:38px;font-size:14px}.container.locked{overflow:hidden}.filter-bar,.nav-bar{display:none}.progress-wrap{border-radius:12px;padding:10px 14px}.progress-top{margin-bottom:6px;font-size:12px}.score-grid{gap:14px;margin-top:6px;font-size:12px}.score-grid .ok b,.score-grid .no b,.score-grid .rate b{font-size:14px}.question-card{border-radius:12px;padding:14px}.q-title{font-size:15.5px}.opt{padding:12px}.opt .key{flex:0 0 28px;height:28px;font-size:14px}.opt .text{font-size:15px}.blank-input{padding:12px;font-size:16px}.feedback{padding:12px;font-size:13.5px}.action-bar{display:flex}.question-card .actions{display:none}.empty-tip{padding:30px 0}}