.linear{
    width:15vw;
    height:2px;
    background-color:#e5e5e5;
    overflow:hidden;
    border:none;
    outline:none;
    margin:auto auto;
}
.alternate{
    width:10px;
    height:100vh;
    background-color:#017a10;
    border:none;
    outline:none;
    transition:all 0.5s;
	animation:preload 0.9s linear infinite alternate;
}
@keyframes preload { 
    0%{
        margin-left:0;
        width:50%;
    }
    25%{
        margin-left:25%;
        width:30%;
    }
    50%{
        margin-left:50%;
        width:80%;
    }
    75%{
        margin-right:25%;
        width:30%;
    }
    100%{
        margin-right:0;
        width:50%;
    }
}