:root{--bg:#050615;--panel:#0b1b2b;--accent:#6fb3ff;--muted:#bfcbd6}
html,body{height:100%;margin:0;font-family:Arial,Helvetica,sans-serif;background:var(--bg);color:#e8eef6}
#ui{position:relative;width:720px;max-width:94%;margin:18px auto}
canvas{display:block;border:4px solid #061222;background:linear-gradient(#051020,#071026);width:100%;height:auto}
/* background canvas sits behind the game canvas */
#bg{position:absolute;left:0;top:0;width:100%;height:100%;z-index:0;border-radius:8px;pointer-events:none}
canvas#game{position:relative;z-index:1}
#overlay{position:absolute;left:0;top:0;width:100%;height:100%;display:flex;flex-direction:column;align-items:center;justify-content:center;backdrop-filter:blur(2px);z-index:3}
.hidden{display:none}
.menu h1{font-size:38px;margin:0 0 12px}
#overlay.hidden{display:none}
.menu h1{font-size:38px;margin:0 0 12px}
.buttons{display:flex;flex-direction:column;gap:10px}
button{background:var(--panel);color:var(--muted);padding:12px 20px;border-radius:8px;border:1px solid rgba(255,255,255,0.04);cursor:pointer}
button:hover{background:#123247;color:#fff}
.hidden{display:none}
#shop,#highs{position:absolute;left:50%;top:50%;transform:translate(-50%,-50%);background:#081222;padding:16px;border-radius:10px;box-shadow:0 8px 32px rgba(0,0,0,0.6);width:420px}
#shop h2,#highs h2{margin:0 0 12px}
#shop-items{display:flex;flex-direction:column;gap:8px;margin-bottom:8px}
.shop-item{display:flex;justify-content:space-between;align-items:center;padding:8px;background:#071826;border-radius:6px}
.hud{position:absolute;left:10px;top:10px;color:var(--muted);font-size:14px}