style.css

body{
    background: rgb(6,164,255);
    background: -moz-linear-gradient(top, rgb(6,164,255) 0%, rgb(35,136,203) 100%, rgb(0,0,0) 100%);
    background: -webkit-linear-gradient(top, rgb(6,164,255) 0%, rgb(35,136,203) 100%, rgb(0,0,0) 100%);
    background: linear-gradient(to bottom, rgb(6,164,255) 0%, rgb(35,136,203) 100%, rgb(0,0,0) 100%);
}
html{
    height: 100vh;
}
h1{
    text-align: center;
    font-family: 'Alfa Slab One', cursive;
    font-size: 50px;
    background: -webkit-linear-gradient(blue 0%, lightgrey 50%, #FFF 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}
.container {
    background-color: lightgrey;
    width: 253px;
    height: 253px;
    border: 2px solid green;
    padding: 1px;
    margin: 1px;
    margin-left: 40vw;
    background : transparent;
}
.case {
    background-color: rgba(20,20,20,0.2);
    width: 20px;
    height: 20px;
    border: 2px solid blue;
    padding: 25px;
    margin: 5px;
    float: left;
}
.case:hover {
    background-color: lightgrey;
    width: 20px;
    height: 20px;
    border: 2px solid blue;
    padding: 25px;
    margin: 5px;
    float: left;
}