html {
  background: linear-gradient(to left, #56ab2f, #a8e063);
  font-family: 'Poppins', sans-serif;
  overflow: hidden;
  transition: background 1000ms;
}
game {
  display: block;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
}
game table {
  opacity: 1;
  transition: opacity 650ms ease;
}
game table.completed {
  opacity: 0;
}
game table td {
  width: 42px;
  height: 42px;
  opacity: 0.4;
  transition: all 175ms linear;
  line-height: 42px;
  text-align: center;
  font-size: 38px;
  color: rgba(0, 0, 0, 0);
}
game table td.walkable {
  background: black;
}
game table td.filled,
game table td.mover {
  background: gray;
  color: white;
}
#reset-button {
  display: inline-block;
  padding: 24px;
  text-decoration: none;
  font-size: 42px;
  transition: all 220ms ease;
  border-radius: 50%;
}
#reset-button,
#reset-button:visited {
  color: rgba(0, 0, 0, 0.6);
}
#reset-button:active {
  color: rgba(255, 255, 255, 0.6);
  background: rgba(255, 255, 255, 0.2);
}