.simplescrollup__button {
    position: fixed;
    bottom: 3rem;
    right: 3rem;
    transition: 1s all;
    z-index: 10000;
}
.simplescrollup__button--show {
    transform: translateX(0);
}
.simplescrollup__button--hide {
    transform: translateX(100px);
}

/*
<a href="#up" duraction="1000" height-hide="100" easing="easeInOutQuad" class="simplescrollup__button simplescrollup__button--hide">Your text</a>

    duration: Time in milliseconds that it will take to go up above the page.
	
    height-hide: Distance in pixels from top at which button will be displayed.
	
    easing: You can change the animation scroll for any of this list. Probado y no cambia nada.
        linear
        easeInQuad
        easeOutQuad
        easeInOutQuad
        easeInCubic
        easeOutCubic
        easeInOutCubic
        easeInQuart
        easeOutQuart
        easeInOutQuart
        easeInQuint
        easeOutQuint
        easeInOutQuint

*/