:root { color-scheme: dark; }
* { box-sizing: border-box; }
html, body, main { margin: 0; width: 100%; height: 100%; }
body { background: #536676 url("poster.jpg") center / cover no-repeat; overflow: hidden; }
video { display: block; width: 100%; height: 100%; object-fit: cover; }
button {
  position: fixed; right: max(20px, env(safe-area-inset-right));
  bottom: max(20px, env(safe-area-inset-bottom)); padding: 10px 16px;
  border: 1px solid #ffffff80; border-radius: 24px;
  color: #fff; background: #15232bcc; font: 14px/1.4 system-ui, sans-serif;
  cursor: pointer;
}
button:hover { background: #15232b; }
button:focus-visible { outline: 3px solid white; outline-offset: 4px; }
[hidden] { display: none; }