:root{--g:30px;--ink:#1e3a5f;--grid-c:#c3d4e3;--paper:#fdfaf3;--accent:#1d4ed8;--danger:#dc2626;--light:#f1f5f9;--border:#e2e8f0}*{box-sizing:border-box;margin:0;padding:0}.ops-wrapper{background:var(--light);min-height:100vh;padding-bottom:4rem;font-family:Segoe UI,system-ui,sans-serif}.ops-topbar{justify-content:space-between;align-items:center;max-width:1280px;margin:0 auto;padding:1.5rem 5% 1rem;display:flex}.btn-back{color:#0f172a;border:1px solid var(--border);background:#fff;border-radius:99px;align-items:center;gap:.5rem;padding:.6rem 1.2rem;font-size:.9rem;font-weight:600;text-decoration:none;transition:all .2s;display:inline-flex;box-shadow:0 2px 4px #0000000a}.btn-back:hover{background:#f8fafc;transform:translateY(-1px)}.ops-header{text-align:center;max-width:1280px;margin:0 auto;padding:0 5% 2rem}.ops-header h1{color:var(--ink);letter-spacing:-.02em;margin-bottom:.5rem;font-size:2.4rem;font-weight:800}.ops-header p{color:#64748b;max-width:640px;margin:0 auto;font-size:1.05rem}.controls-panel{max-width:1280px;margin:0 auto 2rem;padding:0 5%}.ctrl-card{border:1px solid var(--border);background:#fff;border-radius:16px;padding:1.75rem 2rem;box-shadow:0 4px 12px #0000000a}.ctrl-grid{grid-template-columns:repeat(auto-fit,minmax(180px,1fr));gap:1.1rem;margin-bottom:1.5rem;display:grid}.ctrl-group{flex-direction:column;gap:.4rem;display:flex}.ctrl-group label{text-transform:uppercase;letter-spacing:.06em;color:#64748b;font-size:.75rem;font-weight:700}.ctrl-group select,.ctrl-group input{border:1px solid var(--border);color:#0f172a;background:#f8fafc;border-radius:8px;outline:none;padding:.55rem .85rem;font-size:.9rem;transition:border-color .2s}.ctrl-group select:focus,.ctrl-group input:focus{border-color:var(--accent);background:#fff}.toggle-row{flex-wrap:wrap;align-items:center;gap:.75rem;margin-bottom:.8rem;display:flex}.toggle-label{color:#374151;font-size:.9rem;font-weight:600}.toggle-sub{color:#64748b;font-size:.78rem}.t-switch{flex-shrink:0;width:48px;height:26px;position:relative}.t-switch input{opacity:0;width:0;height:0}.t-slider{cursor:pointer;background:#cbd5e1;border-radius:99px;transition:all .3s;position:absolute;inset:0}.t-slider:before{content:"";background:#fff;border-radius:50%;width:20px;height:20px;transition:all .3s;position:absolute;top:3px;left:3px}.t-switch input:checked+.t-slider{background:var(--accent)}.t-switch input:checked+.t-slider:before{transform:translate(22px)}.action-row{border-top:1px solid var(--border);flex-wrap:wrap;align-items:center;gap:1rem;padding-top:1.2rem;display:flex}.btn-primary{background:var(--accent);color:#fff;cursor:pointer;border:none;border-radius:10px;align-items:center;gap:.5rem;padding:.7rem 1.6rem;font-size:.95rem;font-weight:700;transition:all .2s;display:inline-flex;box-shadow:0 4px 12px #1d4ed840}.btn-primary:hover{background:#1e40af;transform:translateY(-1px)}.btn-print{color:#15803d;cursor:pointer;background:#f0fdf4;border:1px solid #86efac;border-radius:10px;align-items:center;gap:.5rem;padding:.7rem 1.4rem;font-size:.95rem;font-weight:700;transition:all .2s;display:inline-flex}.btn-print:hover{background:#dcfce7}.print-tip{color:#94a3b8;margin-left:auto;font-size:.78rem}.worksheet-area{max-width:1280px;margin:0 auto;padding:0 5%}#worksheet{background:var(--paper);background-image:linear-gradient(var(--grid-c) 1px, transparent 1px), linear-gradient(90deg, var(--grid-c) 1px, transparent 1px);background-size:var(--g) var(--g);border:1px solid #d1d5db;border-radius:12px;min-height:500px;padding:30px;overflow-x:auto;box-shadow:0 8px 24px #00000014}.sheet-hdr{border-bottom:2px solid var(--ink);box-sizing:border-box;justify-content:space-between;align-items:flex-end;height:60px;margin-bottom:30px;padding-bottom:12px;display:flex}.sheet-title{color:var(--ink);text-transform:uppercase;letter-spacing:.08em;font-size:.95rem;font-weight:800}.sheet-meta{flex-wrap:wrap;gap:20px;display:flex}.meta-f{color:#374151;border-bottom:1.5px solid #374151;min-width:100px;padding-bottom:2px;font-size:.85rem}.meta-l{color:#64748b;margin-bottom:2px;font-size:.73rem;display:block}.ops-grid{flex-direction:column;gap:60px;display:flex}.ws-empty{color:#94a3b8;text-align:center;flex-direction:column;justify-content:center;align-items:center;gap:1rem;min-height:420px;display:flex}.ws-empty .icon{font-size:3.5rem}.ws-empty p{font-size:1.05rem;font-weight:500}.op-block{min-height:60px;color:var(--ink);flex-wrap:nowrap;justify-content:flex-start;align-items:center;font-family:Courier New,Courier,monospace;font-size:1.6rem;font-weight:700;display:flex;position:relative}.op-num{color:#94a3b8;font-family:sans-serif;font-size:.7rem;font-weight:700;position:absolute;top:-20px;left:-25px}.f-term{align-items:center;height:60px;margin:0 6px;display:flex}.f-whole{color:var(--ink);margin-right:4px;font-size:1.8rem}.f-frac{flex-direction:column;justify-content:center;align-items:center;min-width:25px;height:60px;display:flex}.f-num,.f-den{justify-content:center;width:100%;height:30px;padding:0 4px;display:flex}.f-num{border-bottom:2px solid var(--ink);align-items:flex-end;padding-bottom:2px}.f-den{align-items:flex-start;padding-top:2px}.f-op{color:var(--ink);margin:0 6px;font-size:1.6rem}.f-paren{margin:0 2px;font-size:3.5rem;font-weight:200;line-height:.8;transform:translateY(-3px)}.f-exp{align-self:flex-start;margin-top:-6px;margin-left:2px;font-size:1.2rem}.f-root-wrap{align-items:stretch;margin:0 4px;display:flex}.f-root-svg{width:18px;color:var(--ink);flex-shrink:0;margin-top:6px;margin-right:-1px}.f-radicand{border-top:2px solid var(--ink);margin-top:6px;padding-top:4px;padding-left:2px;padding-right:6px}.f-ans{color:var(--danger);flex-wrap:wrap;align-items:center;display:flex}.f-ans .f-whole,.f-ans .f-num,.f-ans .f-den,.f-ans .f-op,.f-ans .f-paren,.f-ans .f-exp,.f-ans .f-root-svg{color:var(--danger)}.f-ans .f-num,.f-ans .f-radicand{border-color:var(--danger)}#worksheet.hide-answers .f-ans{visibility:hidden}@media (width<=720px){#worksheet{padding:24px 14px}.ctrl-grid{grid-template-columns:1fr 1fr}.print-tip{display:none}.op-block{margin-left:20px}}@media (width<=480px){.ctrl-grid{grid-template-columns:1fr}.ops-header h1{font-size:1.8rem}}@media 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