.sub-stack{
    background:#910c3e;position:absolute;top:0;left:0;width:100%;height:70px;
}
.site-login,.site-signup{
    text-wrap: nowrap;
    padding: 30px;
    background: white;
    /* add width bassed on screen */
    width: 100%;
    border-radius: 20px 20px 0px 0px;
    margin: 0;
    height: calc(100vh - 50px) !important;
    display: block;
    position: absolute;
    margin-top: 50px;

}
input{
    width: 300px;
}
.site-login a{
    text-decoration: none;
}
.site-signup a{
    text-decoration: none;
}
@media screen and (max-width: 768px){
    .site-login,.site-signup{
        padding: 20px !important;
        width: 100%;

    }

}