*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  background: radial-gradient(900px 520px at 30% 15%, rgba(125, 211, 252, .55), transparent 55%),
              radial-gradient(700px 420px at 70% 20%, rgba(34, 197, 94, .25), transparent 60%),
              linear-gradient(180deg, #ffffff, #f5f7fb);
  color:#111827;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial;
}
.ui{
  position: fixed;
  top: 14px;
  left: 14px;
  z-index: 10;
}
.ui-card{
  background: rgba(255,255,255,.72);
  border: 1px solid rgba(15, 23, 42, .10);
  border-radius: 12px;
  box-shadow: 0 10px 28px rgba(0,0,0,.10);
  backdrop-filter: blur(8px);
  padding: 8px;
  display: flex;
  gap: 8px;
}
.ui-btn{
  appearance: none;
  border: 1px solid rgba(15, 23, 42, .16);
  background: rgba(255,255,255,.85);
  color: #111827;
  font-weight: 700;
  padding: 8px 10px;
  border-radius: 10px;
  cursor: pointer;
}
.ui-btn:hover{
  background: #ffffff;
}
.ui-btn:active{
  transform: translateY(1px);
}
.page{
  height:100%;
  display:flex;
  align-items:center;
  justify-content:center;
  padding:28px 14px;
}
canvas#game{
  width:min(100%, 1200px);
  height:auto;
  display:block;
  background: rgba(255,255,255,.55);
  border-radius: 14px;
  box-shadow: 0 16px 45px rgba(0,0,0,.12);
}