*{
margin: 0;
padding: 0;
box-sizing: border-box;
}
#controls:fullscreen {
  background-color: grey;
}
.header img {
width: 60px;
}

.pong-wrapper {
display: flex;
justify-content: center;
align-items: center;
margin-top: 20px;
margin-bottom: 20px;
background-color: black;
padding: 20px;
}

.buttons {
  display: flex;
  justify-content: space-around;
}
.buttons button {
  text-align: center;
  width: 24%;
}

#ping-pong {
width: 80%;
max-width: 680px;
border: 12px solid white;
}

#ping-pong:fullscreen {
  height: 80%;
  max-width: 5000px;
  width: 90%;
}

@media screen and (max-width: 480px) {
.header img {
width: 40px;
}
}