body {
  margin: 0;
  font-size: 32px;
}
canvas {
  width: 100vw;
  height: 100vh;
  display: block;
}

#menu-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  display: flex;
  flex-direction: row;
  justify-content: center;
  align-items: center;
  background: rgba(0, 0, 0, 0.35); /* dim background */
  color: white;
  font-family: sans-serif;
  gap: 1rem;
}

#menu-overlay.hidden {
  display: none;
}

#menu-center-content {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  color: white;
  gap: 1rem;
}

#menu-left-panel {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: flex-start;
  align-self: flex-end;
}

#menu-right-panel {
  display: flex;
  flex-direction: column;
  justify-content: flex-end;
  align-items: flex-end;
  align-self: flex-end;
}

div, input, button, select {
  font-size: inherit;
  font-family: inherit;
}

.spacer {
  padding-top: 0.75rem;
}

.panel {
  flex: 1; /* each panel takes equal space */
  padding: 1rem;
  /* border: 1px solid #ccc; */
}