* { box-sizing: border-box; font-family: Arial, sans-serif; }

body {
  margin: 0;
  color: white;
  background: black;
  overflow: hidden;
}

header {
  position: relative;
  z-index: 2;
  padding: 10px;
  text-align: center;
  background: rgba(0,0,0,0.6);
}

input {
  padding: 8px;
  width: 60%;
  max-width: 400px;
}

button {
  padding: 8px 12px;
}

main {
  position: relative;
  z-index: 2;
  height: calc(100vh - 80px);
}

iframe {
  width: 100%;
  height: 100%;
  border: none;
}

canvas {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 0;
}