:root{color-scheme:dark;--bg: #0b1120;--surface: #131c31;--surface-elevated: #1e293b;--border: #334155;--fg: #e2e8f0;--fg-strong: #f8fafc;--muted: #94a3b8;--faint: #64748b;--accent: #38bdf8;--accent-strong: #0284c7;--gold: #f59e0b;--success-bg: rgba(16, 185, 129, .16);--success-border: rgba(52, 211, 153, .45);--success-text: #6ee7b7;--error-bg: rgba(239, 68, 68, .18);--error-border: rgba(248, 113, 113, .45);--error-text: #fca5a5;--hint-bg: rgba(56, 189, 248, .14);--hint-border: rgba(56, 189, 248, .45);--focus: #38bdf8;--font-sans: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif}:root[data-theme=light]{color-scheme:light;--bg: #f1f5f9;--surface: #ffffff;--surface-elevated: #e2e8f0;--border: #cbd5e1;--fg: #1e293b;--fg-strong: #0f172a;--muted: #475569;--faint: #64748b;--accent: #0284c7;--accent-strong: #0369a1;--gold: #d97706;--success-bg: rgba(16, 185, 129, .15);--success-border: rgba(5, 150, 105, .4);--success-text: #047857;--error-bg: rgba(239, 68, 68, .14);--error-border: rgba(220, 38, 38, .4);--error-text: #b91c1c;--hint-bg: rgba(2, 132, 199, .12);--hint-border: rgba(2, 132, 199, .4);--focus: #0284c7}*,*:before,*:after{box-sizing:border-box;margin:0}html,body{height:100%;overscroll-behavior:none}body{background:var(--bg);color:var(--fg);font-family:var(--font-sans);line-height:1.4;-webkit-font-smoothing:antialiased;user-select:none;-webkit-user-select:none}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}.app-shell{height:100dvh;max-width:680px;margin:0 auto;display:flex;flex-direction:column;padding:env(safe-area-inset-top,0px) env(safe-area-inset-right,0px) env(safe-area-inset-bottom,0px) env(safe-area-inset-left,0px)}.topbar{display:flex;align-items:center;justify-content:space-between;gap:.5rem;padding:.55rem .75rem;border-bottom:1px solid var(--border);background:var(--surface);flex-shrink:0}.brand-group{display:flex;align-items:center;gap:.55rem;min-width:0}.brand-title{display:flex;align-items:center;gap:.35rem}.brand-icon{font-size:1.15rem}.brand-title h1{font-size:1.1rem;font-weight:700;letter-spacing:-.01em;color:var(--fg-strong)}.preset-select{appearance:none;background-color:var(--surface-elevated);color:var(--fg-strong);border:1px solid var(--border);border-radius:.45rem;padding:.35rem 1.65rem .35rem .55rem;font:inherit;font-size:.85rem;font-weight:600;cursor:pointer;background-image:linear-gradient(45deg,transparent 50%,var(--muted) 50%),linear-gradient(135deg,var(--muted) 50%,transparent 50%);background-position:calc(100% - 12px) 52%,calc(100% - 7px) 52%;background-size:5px 5px,5px 5px;background-repeat:no-repeat}.header-actions{display:flex;align-items:center;gap:.4rem;flex-shrink:0}.timer-pill{font-variant-numeric:tabular-nums;font-size:.85rem;font-weight:600;color:var(--muted);padding:.25rem .45rem;border-radius:.375rem;background:var(--bg)}.btn{appearance:none;border:1px solid var(--border);background:var(--surface-elevated);color:var(--fg-strong);font:inherit;font-size:.85rem;font-weight:600;padding:.38rem .7rem;border-radius:.45rem;cursor:pointer;display:inline-flex;align-items:center;justify-content:center;gap:.3rem;transition:background-color .12s ease,border-color .12s ease,transform .06s ease;touch-action:manipulation}.btn:active{transform:scale(.97)}.btn-primary{background:var(--accent-strong);border-color:var(--accent);color:#fff}.btn-secondary{background:var(--surface-elevated);color:var(--fg-strong)}.btn-danger{background:#ef444429;border-color:#ef444473;color:var(--error-text)}.btn-icon{width:2rem;height:2rem;padding:0;font-weight:700}.status-banner{display:flex;align-items:center;justify-content:space-between;gap:.5rem;min-height:2.3rem;padding:.35rem .75rem;font-size:.82rem;color:var(--muted);background:var(--surface);border-bottom:1px solid var(--border);flex-shrink:0}.status-banner.is-solved{background:var(--success-bg);border-bottom-color:var(--success-border);color:var(--success-text);font-weight:600}.status-banner.is-error{background:var(--error-bg);border-bottom-color:var(--error-border);color:var(--error-text)}.status-banner.is-hint{background:var(--hint-bg);border-bottom-color:var(--hint-border);color:var(--fg-strong)}.banner-action-btn{appearance:none;border:1px solid currentColor;background:#ffffff1f;color:inherit;font:inherit;font-size:.78rem;font-weight:700;padding:.22rem .6rem;border-radius:.375rem;cursor:pointer;white-space:nowrap;flex-shrink:0}.board-stage{flex:1 1 auto;min-height:0;display:flex;align-items:flex-end;justify-content:center;padding:.25rem .25rem .5rem;overflow:hidden;position:relative}#board-canvas{display:block;touch-action:none;border-radius:.5rem;outline:none;cursor:pointer}#board-canvas:focus-visible{box-shadow:0 0 0 2px var(--focus)}.controls-dock{flex-shrink:0;background:var(--surface);border-top:1px solid var(--border);padding:.5rem .65rem .35rem;display:flex;flex-direction:column;gap:.45rem}.tool-switcher{display:grid;grid-template-columns:repeat(4,1fr);gap:.35rem;background:var(--bg);padding:.25rem;border-radius:.55rem;border:1px solid var(--border)}.tool-btn{appearance:none;border:1px solid transparent;background:transparent;color:var(--muted);font:inherit;font-size:.78rem;font-weight:600;padding:.42rem .25rem;border-radius:.4rem;cursor:pointer;display:flex;align-items:center;justify-content:center;gap:.3rem;touch-action:manipulation;transition:background-color .12s ease,color .12s ease}.tool-btn.active{background:var(--surface-elevated);border-color:var(--accent);color:var(--fg-strong);box-shadow:0 1px 3px #00000040}.tool-symbol{font-size:.95rem;line-height:1}.action-bar{display:grid;grid-template-columns:repeat(4,1fr);gap:.35rem}.action-btn{appearance:none;border:1px solid var(--border);background:var(--surface-elevated);color:var(--fg-strong);font:inherit;font-size:.8rem;font-weight:600;padding:.45rem .35rem;border-radius:.45rem;cursor:pointer;display:flex;align-items:center;justify-content:center;gap:.28rem;touch-action:manipulation}.action-btn:disabled{opacity:.4;cursor:default}.action-btn:not(:disabled):active{transform:scale(.97)}.app-footer{flex-shrink:0;padding:.25rem .75rem .35rem;background:var(--surface);display:flex;justify-content:center}.app-footer nav{display:flex;align-items:center;gap:.4rem;font-size:.75rem;color:var(--faint)}.seed-pill{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;color:var(--muted)}.legal-button{appearance:none;background:none;border:0;padding:.15rem .4rem;border-radius:.25rem;color:inherit;font:inherit;cursor:pointer}.legal-button:hover{background:#94a3b826;color:var(--fg)}.link{color:var(--accent);text-decoration:underline}dialog{margin:auto;width:min(34rem,calc(100vw - 1.5rem));max-height:86dvh;overflow-y:auto;padding:0;border:1px solid var(--border);border-radius:.75rem;background:var(--surface);color:var(--fg);box-shadow:0 25px 50px -12px #000000a6;user-select:text;-webkit-user-select:text}dialog::backdrop{background:#020617b8;-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px)}.dialog-body{padding:1.25rem;font-size:.92rem}.dialog-body header{display:flex;align-items:center;justify-content:space-between;gap:1rem;margin-bottom:.85rem}.dialog-body h2{font-size:1.2rem;font-weight:700;color:var(--fg-strong)}.dialog-body h3{margin:1rem 0 .4rem;font-size:.98rem;font-weight:700;color:var(--fg-strong)}.dialog-body p{margin-top:.5rem}.dialog-list{padding-left:1.2rem;display:flex;flex-direction:column;gap:.45rem}.dialog-credit{margin-top:1rem;font-size:.82rem;color:var(--muted)}.menu-stack{display:flex;flex-direction:column;gap:.85rem}.menu-row{display:flex;align-items:center;justify-content:space-between;padding:.55rem .75rem;background:var(--bg);border:1px solid var(--border);border-radius:.5rem}.seed-code{font-family:ui-monospace,SFMono-Regular,Menlo,Monaco,Consolas,monospace;font-size:.88rem;color:var(--accent)}.menu-actions-grid{display:grid;grid-template-columns:1fr 1fr;gap:.5rem}@media(max-width:400px){.brand-title h1{font-size:.98rem}.tool-label{font-size:.72rem}.menu-actions-grid{grid-template-columns:1fr}}