:root{--bg:#0f172a;--bg-card:#1e293b;--bg-cell:#1e293b;--bg-cell-original:#334155;--bg-cell-selected:#1e3a5f;--bg-highlight:#1e293b;--bg-highlight-subtle:#1a2744;--bg-error:#ef444426;--bg-error-intense:#ef44444d;--bg-success:#22c55e26;--bg-hover:#2d3a52;--text-primary:#f1f5f9;--text-secondary:#94a3b8;--text-muted:#64748b;--text-original:#e2e8f0;--text-user:#60a5fa;--text-error:#ef4444;--text-success:#22c55e;--border:#334155;--border-thick:#64748b;--border-selected:#3b82f6;--border-error:#ef4444;--primary:#3b82f6;--primary-hover:#2563eb;--primary-active:#1d4ed8;--danger:#ef4444;--danger-hover:#dc2626;--success:#22c55e;--cell-size:clamp(2.2rem, 7vw, 3.2rem);--board-size:calc(var(--cell-size) * 9);--radius-sm:4px;--radius-md:8px;--radius-lg:12px;--shadow-card:0 4px 24px #0000004d;--transition:.15s ease}*,:before,:after{box-sizing:border-box;margin:0;padding:0}html{-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale}body{background:var(--bg);color:var(--text-primary);justify-content:center;align-items:flex-start;min-height:100dvh;padding:1rem;font-family:Inter,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;line-height:1.5;display:flex}#app{flex-direction:column;align-items:center;gap:1rem;width:100%;max-width:540px;padding-top:1.5rem;display:flex}.game-title{letter-spacing:.15em;text-transform:uppercase;color:var(--primary);-webkit-user-select:none;user-select:none;font-size:1.75rem;font-weight:700}.game-card{background:var(--bg-card);border-radius:var(--radius-lg);box-shadow:var(--shadow-card);flex-direction:column;align-items:center;gap:1rem;width:100%;padding:1.5rem;display:flex}.status-bar{justify-content:space-between;align-items:center;width:100%;padding:0 .25rem;display:flex}.status-item{color:var(--text-secondary);align-items:center;gap:.4rem;font-size:.875rem;font-weight:500;display:flex}.status-item .icon{opacity:.7;width:1rem;height:1rem}.status-item .value{font-variant-numeric:tabular-nums;color:var(--text-primary);min-width:2.5rem}.status-item .value--errors{color:var(--text-error)}.overlay{z-index:100;opacity:0;pointer-events:none;background:#0009;justify-content:center;align-items:center;transition:opacity .3s;display:flex;position:fixed;inset:0}.overlay--active{opacity:1;pointer-events:auto}.modal{background:var(--bg-card);border-radius:var(--radius-lg);text-align:center;width:90%;max-width:400px;box-shadow:var(--shadow-card);padding:2rem;transition:transform .3s;transform:translateY(1rem)scale(.95)}.overlay--active .modal{transform:translateY(0)scale(1)}.modal__title{margin-bottom:.5rem;font-size:1.25rem;font-weight:600}.modal__text{color:var(--text-secondary);margin-bottom:1.5rem;font-size:.9rem}.modal__text strong{color:var(--text-primary)}.modal__actions{flex-direction:column;gap:.5rem;display:flex}.difficulty-modal .modal__title{margin-bottom:1rem}@keyframes fadeIn{0%{opacity:0;transform:scale(.9)}to{opacity:1;transform:scale(1)}}@keyframes slideUp{0%{opacity:0;transform:translateY(1rem)}to{opacity:1;transform:translateY(0)}}@keyframes pulse{0%,to{transform:scale(1)}50%{transform:scale(1.05)}}.board-wrapper{width:var(--board-size);height:var(--board-size);flex-shrink:0;position:relative}.board{border:2px solid var(--border-thick);border-radius:var(--radius-sm);-webkit-user-select:none;user-select:none;background:var(--border);grid-template-rows:repeat(9,1fr);grid-template-columns:repeat(9,1fr);width:100%;height:100%;display:grid;overflow:hidden}.cell{font-size:calc(var(--cell-size) * .55);background:var(--bg-cell);cursor:pointer;transition:background var(--transition), color var(--transition);border:1px solid var(--border);outline:none;justify-content:center;align-items:center;font-weight:500;display:flex;position:relative}.cell:after{content:"";pointer-events:none;position:absolute;inset:0}.cell--original{color:var(--text-original);background:var(--bg-cell-original);cursor:default;font-weight:700}.cell--user{color:var(--text-user)}.cell--highlight{background:var(--bg-highlight)}.cell--highlight-subtle{background:var(--bg-highlight-subtle)}.cell--selected{box-shadow:inset 0 0 0 2px var(--border-selected);z-index:2;background:var(--bg-cell-selected)!important}.cell--error{background:var(--bg-error)!important;color:var(--text-error)!important}.cell--error:after{border:2px solid var(--border-error)}.cell--same-number{background:var(--bg-highlight)}.cell--border-right{border-right-width:2px;border-right-color:var(--border-thick)}.cell--border-bottom{border-bottom-width:2px;border-bottom-color:var(--border-thick)}.cell--anim-pop{animation:.2s cellPop}@keyframes cellPop{0%{transform:scale(.8)}50%{transform:scale(1.1)}to{transform:scale(1)}}@keyframes shake{0%,to{transform:translate(0)}20%{transform:translate(-3px)}40%{transform:translate(3px)}60%{transform:translate(-2px)}80%{transform:translate(2px)}}.cell--shake{animation:.3s shake}.controls{width:var(--board-size);flex-direction:column;gap:.75rem;display:flex}.numpad{grid-template-columns:repeat(10,1fr);gap:.35rem;display:grid}.numpad__btn{border:1px solid var(--border);border-radius:var(--radius-md);background:var(--bg-card);height:2.5rem;color:var(--text-primary);cursor:pointer;transition:background var(--transition), border-color var(--transition), transform var(--transition);justify-content:center;align-items:center;font-size:1rem;font-weight:600;display:flex}.numpad__btn:hover{background:var(--bg-hover);border-color:var(--primary)}.numpad__btn:active{transform:scale(.92)}.numpad__btn--erase{color:var(--text-error);letter-spacing:.05em;font-size:.75rem}.numpad__btn--disabled{opacity:.3;cursor:default;pointer-events:none}.numpad__btn--complete{border-color:var(--success);color:var(--success)}.action-buttons{grid-template-columns:repeat(3,1fr);gap:.5rem;display:grid}.btn{border-radius:var(--radius-md);cursor:pointer;transition:background var(--transition), transform var(--transition), opacity var(--transition);white-space:nowrap;border:none;justify-content:center;align-items:center;gap:.35rem;padding:.6rem .75rem;font-size:.8rem;font-weight:600;display:flex}.btn:active{transform:scale(.95)}.btn--primary{background:var(--primary);color:#fff}.btn--primary:hover{background:var(--primary-hover)}.btn--secondary{color:var(--text-secondary);border:1px solid var(--border);background:0 0}.btn--secondary:hover{background:var(--bg-hover);color:var(--text-primary)}.btn--danger{color:var(--text-error);border:1px solid var(--border);background:0 0}.btn--danger:hover{background:var(--bg-error-intense);border-color:var(--text-error)}.btn--success{background:var(--success);color:#fff}.btn--success:hover{background:#16a34a}.btn--ghost{color:var(--text-secondary);border:1px solid var(--border);background:0 0;width:100%}.btn--ghost:hover{background:var(--bg-hover);color:var(--text-primary)}@media (width<=560px){body{align-items:flex-start;padding:.5rem}#app{gap:.65rem;padding-top:.75rem}.game-title{font-size:1.25rem}.game-card{border-radius:var(--radius-md);gap:.65rem;padding:.75rem}:root{--cell-size:clamp(1.8rem, 10vw, 2.5rem)}.status-item{font-size:.75rem}.numpad{gap:.25rem}.numpad__btn{border-radius:var(--radius-sm);height:2.2rem;font-size:.85rem}.action-buttons{grid-template-columns:repeat(3,1fr);gap:.35rem}.btn{padding:.5rem;font-size:.7rem}.modal{padding:1.5rem}}@media (width<=380px){:root{--cell-size:clamp(1.5rem, 9vw, 2rem)}.cell{font-size:calc(var(--cell-size) * .5)}.game-card{padding:.5rem}.numpad__btn{height:1.8rem;font-size:.75rem}}@media (width>=768px){body{padding:2rem}#app{gap:1.25rem;padding-top:2rem}.game-card{padding:2rem}.numpad__btn:hover{background:var(--bg-hover);border-color:var(--primary)}}@media (hover:none){.numpad__btn:hover{background:var(--bg-card);border-color:var(--border)}.btn:hover{transform:none}}