.pos-a{
    position: absolute;
}

.pos-a-top{
    position: absolute;
    top:0;
    left:0;
}

.pos-a-bottom{
    position: absolute;
    bottom:0;
    left:0;
}


.pos-f{
    position: fixed;
}

.pos-f-top{
    position: fixed;
    top:0;
    left:0;
}

.pos-f-bottom{
    position: fixed;
    bottom:0;
    left:0;
}


.pos-r{
    position: relative;
}

.pos-s{
    position: sticky;
}


.pos-s-top{
    position: sticky;
    top:0;
    left:0;
}

.pos-s-bottom{
    position: sticky;
    bottom:0;
    left:0;
}