:root{--spinner-duration: .8s}@keyframes spin{to{transform:rotate(360deg)}}.spinner{animation:spin var(--spinner-duration) linear infinite;display:inline-block}:root{--bg-chalkboard: #ffffff;--bg-chalkboard-dark: #fafaf8;--bg-card: #ffffff;--bg-card-hover: #f4f3ef;--bg-page: #fafaf8;--bg: #f4f4f0;--bg-soft: #efefea;--bg-user-bubble: #eef2ff;--chalk: #1a1a1a;--chalk-dim: #5b5b5b;--chalk-muted: #8b8b8b;--text-primary: #1a1a1a;--text-secondary: #5b5b5b;--accent: #4f46e5;--accent-yellow: #eab308;--accent-orange: #f97316;--accent-red: #dc2626;--accent-green: #16a34a;--accent-blue: #2563eb;--accent-cyan: #0891b2;--border-chalk: #e8e8e6;--border-strong: #d0d0ce;--border-color: #e8e8e6;--shadow-chalk: 0 1px 2px rgba(0, 0, 0, .04), 0 4px 12px rgba(0, 0, 0, .05);--shadow-card: 0 1px 3px rgba(0, 0, 0, .04), 0 6px 20px rgba(0, 0, 0, .06);--radius: 16px;--radius-sm: 10px;--radius-lg: 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bounce{0%,80%,to{transform:translateY(0);opacity:.5}40%{transform:translateY(-4px);opacity:1}}.solve-right{flex:1;min-width:0;display:flex;flex-direction:column;background:var(--bg-page)}.solve-right-inner{display:flex;flex-direction:column;height:100%}.solve-r-header{display:flex;align-items:center;gap:10px;padding:12px 16px;border-bottom:1px solid var(--border-chalk);background:var(--bg-chalkboard-dark)}.solve-r-header .solve-back{background:transparent;border:none;color:var(--chalk);font-size:24px;padding:0 4px;cursor:pointer;line-height:1}.solve-r-title{flex:1;font-size:15px;font-weight:600}.solve-r-balance{font-size:13px;color:var(--accent-yellow);cursor:pointer;padding:4px 10px;background:#f2d16b1a;border-radius:14px}.solve-r-subjects{display:flex;align-items:center;gap:4px;padding:8px 12px;border-bottom:1px solid 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