HTMLify

body{
    height: 100vh;
}
.start-btn{
    margin-top: -100px;
    margin-bottom: 10px;
    width: 80%;
    padding: 10px;
    font-size: 22px;
}
img{
    width: 100%;
    height: 100%;
}
.container, .row, .col-md-3{
    display: flex;
    justify-content: center;
    align-items: center;
}
.container{
    height: 100%;
    flex-direction: column;
}
.row{
    width: 100%;
}
.col-md-3{
    color: aliceblue;
    height: 450px;
    font-size: 80px;
    background-color: rgb(129, 137, 193);
    margin: 15px;
}
.col-md-3:hover{
    border: 5px solid rgb(93, 103, 184);
}

@keyframes swap1 {
    100%{
        transform:translate(-310px, 0px);
    }
}
@keyframes swap2 {
    100%{
        transform:translate(310px, 0px);
    }
}
@keyframes swap3 {
    100%{
        transform:translate(-620px, 0px);
    }
}
@keyframes swap4 {
    100%{
        transform:translate(620px, 0px);
    }
}