styles.css

.smaller-image {
    width: 500px;
  }
.test-test {
  text-align: center;
}
.rot{color:#ff0000;}

.center{
  align: "middle";
}

#game{
    width: 500px;
    height: 200px;
    border: 1px solid black;
    margin: auto;
}

#character{
    width: 20px;
    height: 50px;
    background-color: red;
    position: relative;
    top: 150px; //game height - character height (200 - 50)
}

@keyframes jump{
    0%{top: 150px;}
    30%{top: 100px;}
    70%{top: 100px;}
    100%{top: 150px;}
}

.animate{
    animation: jump 300ms linear;
}

#block{
    width: 20px;
    height: 20px;
    background-color: blue;
    position: relative;
    top: 130px; //game height - character height - block height (200 - 50 - 20)
    left: 480px; //game width - block width (500 - 20)
    animation: block 1s infinite linear;
}

@keyframes block{
    0%{left: 500px} 
    100%{left: -20px}
}