:root{
    --bg1:#f7f8fb;
    --bg2:#e9eef6;
    --ink:#0f172a;           /* deep slate */
    --muted:#94a3b8;         /* slate-400 */
    --accent:#3b82f6;        /* calm blue */
    --accent-2:#22c55e;      /* calm green */
    --shadow: 0 8px 24px rgba(15,23,42,.08);
}
*{box-sizing:border-box}
html,body{
    height:100%;
    margin:0;
    font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, "Helvetica Neue", Arial, "Noto Sans", "Apple Color Emoji","Segoe UI Emoji";
    color:var(--ink);
    background:
    radial-gradient(1200px 800px at 15% -10%, var(--bg2), transparent 60%),
    linear-gradient(180deg, var(--bg1), #fff 60%);
}
.app{
    min-height:100%;
    display:grid;
    grid-template-rows:auto 1fr auto;
}
.topbar{
    position:sticky;
    top:0;
    display:flex;
    align-items:center;
    gap:.75rem;
    padding:16px clamp(12px, 3vw, 28px);
    z-index:10;
}
.home{
    display:inline-flex;
    align-items:center;
    justify-content:center;
    width:40px;height:40px;
    border-radius:12px;
    text-decoration:none;
    font-size:20px;
    box-shadow:var(--shadow);
    background:#fff;
    border:1px solid rgba(15,23,42,.06);
    color:var(--ink);
    transition: transform .15s ease, box-shadow .15s ease, background .2s ease;
    user-select:none;
}
.home:active{ transform: scale(.98) }
.title{
    font-weight:600;
    letter-spacing:.2px;
    opacity:.8;
    font-size:clamp(14px, 1.5vw, 16px);
}
.stage{
    width:min(95vw, 1100px);
    margin: 0px auto 0px;
    background: linear-gradient(180deg, #ffffffc7, #ffffff);
    border:1px solid rgba(15,23,42,.06);
    border-radius:20px;
    box-shadow:var(--shadow);
    padding:clamp(8px, 1.5vw, 16px);
}
/* Keep aspect ratio via CSS, JS sets pixel density */
.canvas-wrap{
    position:relative;
    width:100%;
    aspect-ratio:16/9;
    border-radius:16px;
    overflow:hidden;
    box-shadow: inset 0 0 0 1px rgba(15,23,42,.06);
    background:
    radial-gradient(800px 500px at 80% -10%, #c7e1ff55, transparent 70%),
    linear-gradient(180deg, #f8fbff, #eef5ff);
}
canvas{
    width:100%;
    height:100%;
    display:block;
}
.hint{
    text-align:center;
    margin:8px 0 2px;
    font-size:12px;
    color:var(--muted);
    user-select:none;
}
@media (max-width:480px){
    .home{ width:36px; height:36px; font-size:18px; border-radius:10px }
}