html, body {
  padding: 0;
  margin: 0;
  width: 100%;
  height: 100%;
}
:root {
  --control-panel-height: 1.5em;
  --background-color: #7eb9b9;
}
body {
  background-color: var(--background-color);
  overflow: hidden;
  position: relative;
}
label input[type="checkbox"] {
  margin-left: 1em;
  position: relative;
  top: 0.15em;
}
button:not(.Selected):hover {
  background-color: #ccc;
}