style.css

#screen {
  height: 400px;
  width: 400px;
  outline: thin solid black;
}

.zero {
  display: inline-block;
  vertical-align: top;
  height: 20px;
  width: 20px;
  background-color: black;
}

.one {
  display: inline-block;
  vertical-align: top;
  height: 20px;
  width: 20px;
  background-color: blue;
}

.right {
  display: inline-block;
  vertical-align: top;
  height: 20px;
  background: url('./img/pacmanright.png');
  background-position: center;
  background-size: 20px 20px;
  width: 20px;
  background-color: black;
}
.left {
  display: inline-block;
  vertical-align: top;
  height: 20px;
  background: url('./img/pacmanleft.png');
  background-position: center;
  background-size: 20px 20px;
  width: 20px;
  background-color: black;
}
.up {
  display: inline-block;
  vertical-align: top;
  height: 20px;
  background: url('./img/pacmanup.png');
  background-position: center;
  background-size: 20px 20px;
  width: 20px;
  background-color: black;
}
.down {
  display: inline-block;
  vertical-align: top;
  height: 20px;
  background: url('./img/pacmandown.png');
  background-position: center;
  background-size: 20px 20px;
  width: 20px;
  background-color: black;
}