*{box-sizing:border-box}
html,body{height:100%;margin:0;background:#0e1014;color:#e6e6e6;font-family:system-ui,Segoe UI,Roboto,Arial}
#game{width:100vw;height:100vh}
button.install-btn{position:fixed;right:16px;bottom:16px;padding:10px 14px;border:0;border-radius:12px;font-weight:600;color:#0e1014;background:#9ef01a;cursor:pointer;box-shadow:0 8px 24px rgba(0,0,0,.3)}
button.install-btn[hidden]{display:none}