:root{--font-main: "SF Pro Text", "SF Pro Display", "Google Sans", "Noto Sans SC", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;--radius-xl: 22px;--radius-lg: 16px;--radius-md: 12px;--radius-sm: 10px}:root[data-theme=light]{color-scheme:light;--bg: #f5f5f7;--surface: #ffffff;--surface-elevated: #fafafc;--surface-soft: #f1f1f3;--text-main: #0f1012;--text-subtle: #5e6369;--border: #dddddf;--shadow-soft: 0 8px 20px rgba(0, 0, 0, .05);--shadow-mid: 0 14px 32px rgba(0, 0, 0, .08);--accent: #101113;--accent-contrast: #ffffff;--danger: #c62828;--overlay: rgba(0, 0, 0, .4)}:root[data-theme=dark]{color-scheme:dark;--bg: #000000;--surface: #121212;--surface-elevated: #171719;--surface-soft: #1f2022;--text-main: #f4f5f6;--text-subtle: #aeb2b7;--border: #2f3134;--shadow-soft: 0 10px 22px rgba(0, 0, 0, .4);--shadow-mid: 0 18px 34px rgba(0, 0, 0, .52);--accent: #f3f4f5;--accent-contrast: #121212;--danger: #ff8a80;--overlay: rgba(0, 0, 0, .68)}:root{color-scheme:light;--bg: #f5f5f7;--surface: #ffffff;--surface-elevated: #fafafc;--surface-soft: #f1f1f3;--text-main: #0f1012;--text-subtle: #5e6369;--border: #dddddf;--shadow-soft: 0 8px 20px rgba(0, 0, 0, .05);--shadow-mid: 0 14px 32px rgba(0, 0, 0, .08);--accent: #101113;--accent-contrast: #ffffff;--danger: #c62828;--overlay: rgba(0, 0, 0, .4)}*{box-sizing:border-box}html,body,#root{min-height:100%}body{margin:0;font-family:var(--font-main);background:var(--bg);color:var(--text-main)}button,input,select{font-family:inherit;transition:background-color .16s ease,border-color .16s ease,color .16s ease,box-shadow .16s ease,transform .16s ease}button:focus-visible,input:focus-visible,select:focus-visible{outline:2px solid color-mix(in srgb,var(--accent) 52%,transparent);outline-offset:2px}.ui-icon{width:20px;height:20px;display:block}.icon-button{width:44px;height:44px;padding:0;display:inline-flex;align-items:center;justify-content:center;border:1px solid var(--border);border-radius:12px;background:var(--surface-soft);color:var(--text-main);cursor:pointer}.icon-button:hover{background:var(--surface-elevated);box-shadow:var(--shadow-soft)}.icon-button:active{transform:translateY(1px)}.mode-icon-btn.active{border-color:var(--accent);background:var(--accent);color:var(--accent-contrast)}.login-shell,.fatal-shell{min-height:100vh;display:grid;place-items:center;padding:24px 16px}.login-card,.fatal-shell{width:min(520px,100%);background:var(--surface);border-radius:var(--radius-xl);border:1px solid var(--border);box-shadow:var(--shadow-mid);padding:28px;animation:rise-in .22s ease}.eyebrow{margin:0;letter-spacing:.08em;text-transform:uppercase;color:var(--text-subtle);font-size:12px}.login-card h1,.fatal-shell h1{margin:10px 0 12px;font-size:clamp(24px,3vw,32px)}.login-desc,.fatal-shell p{margin:0;color:var(--text-subtle);line-height:1.55}.login-form{margin-top:18px;display:grid;gap:10px}.login-form label{font-weight:600}.login-form 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ease}.group-toggle{width:100%;display:flex;align-items:center;justify-content:space-between;border:none;background:transparent;color:inherit;padding:10px 12px;font-weight:700;cursor:pointer}.group-count{color:var(--text-subtle);font-size:12px}.group-items{list-style:none;margin:0;padding:0 10px 10px;display:grid;gap:8px}.group-item{width:100%;border:1px solid var(--border);background:var(--surface);border-radius:var(--radius-sm);padding:8px;text-align:left;cursor:pointer;display:grid;gap:2px}.group-item.active{border-color:var(--accent);background:var(--surface-soft)}.group-item-label{font-size:12px;color:var(--text-subtle)}.group-item-text{font-size:13px}.sidebar-backdrop{position:fixed;top:0;right:0;bottom:0;left:0;border:none;background:var(--overlay);z-index:30}.main-panel{position:relative;z-index:5;display:grid;gap:12px}.question-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius-xl);padding:16px;box-shadow:var(--shadow-mid);animation:rise-in .2s ease}.question-header h2{margin:10px 0;font-size:clamp(20px,3vw,28px);line-height:1.38;letter-spacing:-.01em}.question-meta,.question-pages,.question-footer{margin:0;color:var(--text-subtle);font-size:14px;line-height:1.45}.question-actions{margin-top:14px;display:flex;flex-wrap:wrap;gap:8px}.question-actions button{border:1px solid var(--border);background:var(--surface-soft);color:var(--text-main);border-radius:var(--radius-md);padding:9px 14px;cursor:pointer}.question-actions button:first-child{border-color:var(--accent);background:var(--accent);color:var(--accent-contrast);font-weight:650}.answer-card{margin-top:14px;border:1px dashed var(--border);border-radius:var(--radius-md);background:var(--surface-soft);padding:14px}.answer-card.visible{border-style:solid}.answer-text{margin:0;white-space:pre-wrap;line-height:1.62}.answer-placeholder{margin:0;color:var(--text-subtle)}.question-footer{margin-top:14px}.mobile-toolbar{position:fixed;left:50%;bottom:calc(14px + env(safe-area-inset-bottom));transform:translate(-50%);background:color-mix(in srgb,var(--surface) 90%,transparent);border:1px solid var(--border);border-radius:16px;box-shadow:var(--shadow-mid);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);display:flex;align-items:center;gap:8px;padding:8px;z-index:40}.mobile-toolbar .icon-button{width:42px;height:42px}@media (min-width: 960px){.app-shell{padding:24px}.menu-close,.mobile-toolbar{display:none}.workspace{display:grid;grid-template-columns:320px minmax(0,1fr);align-items:start;gap:16px}.sidebar{position:sticky;top:22px;transform:none;width:100%;height:calc(100vh - 58px);border:1px solid var(--border);border-radius:var(--radius-lg);padding:14px}.sidebar-backdrop{display:none}.topbar{grid-template-columns:minmax(0,1fr) auto;gap:14px}.topbar-info{min-width:0}.topbar h1{font-size:30px;line-height:1.15}.topbar p{white-space:normal;overflow:visible;text-overflow:clip;font-size:14px}}@media (max-width: 959px){.desktop-actions,.menu-close{display:none}.topbar{grid-template-columns:minmax(0,1fr)}.topbar p{white-space:normal;overflow:visible;text-overflow:clip}}@keyframes rise-in{0%{opacity:0;transform:translateY(6px)}to{opacity:1;transform:translateY(0)}}