:root {
  --b-color: orange;
  --c-color: white;
  --p-bottom: 30px;
  --p-right: 30px;
  --e-radius: 5px;
  --hb-color: red;
  --hc-color: yellow;
}

.scroll-to-top {
    bottom: var(--p-bottom);
    box-shadow: 0 0 10px rgba(0, 0, 0, .05);
    display: inline-block;
    height: 40px;
    line-height: 40px;
    opacity: 0;
    overflow: hidden;
    position: fixed;
    right: var(--p-right);
    text-align: center;
    -webkit-transition: opacity .3s 0s, visibility 0s .3s;
       -moz-transition: opacity .3s 0s, visibility 0s .3s;
            transition: opacity .3s 0s, visibility 0s .3s;
    vertical-align: middle;
    visibility: hidden;
    white-space: nowrap;
    width: 40px;
    background-color: var(--b-color);
    color: var(--c-color);
    -webkit-border-radius: var(--e-radius); 
    -moz-border-radius: var(--e-radius); 
    border-radius: var(--e-radius);
}
.scroll-to-top:hover {
    background-color: var(--hb-color);
    color: var(--hc-color);
}
.scroll-to-top.scroll-to-top-is-visible,
.scroll-to-top.scroll-to-top-fade-out,
.no-touch .scroll-to-top:hover {
    -webkit-transition: opacity .3s 0s, visibility 0s 0s;
       -moz-transition: opacity .3s 0s, visibility 0s 0s;
            transition: opacity .3s 0s, visibility 0s 0s;
}
.scroll-to-top.scroll-to-top-is-visible {
    opacity: 1;
    /* the button becomes visible */
    visibility: visible;
}
.scroll-to-top.scroll-to-top-fade-out {
    /* if the user keeps scrolling down, the button is out of focus and becomes less visible */
    opacity: .5;
}
.no-touch .scroll-to-top:hover {
    opacity: 1;
}

.tablet .scroll-to-top {
    bottom: 20px;
    right: 20px;
}

.phone .scroll-to-top {
    bottom: 40px;
    height: 40px;
    right: 10px;
    width: 40px;
}

.Size_fa-2x {
    height: 50px;
    width: 50px;    
    line-height: 60px;
}

.Size_fa-3x {
    height: 60px;
    width: 60px;
    line-height: 80px;
}

.Size_fa-4x {
    height: 70px;
    width: 70px;
    line-height: 100px;
}

.Size_fa-5x {
    height: 90px;
    width: 90px;
    line-height: 130px;
}

.scroll-to-top {
    
    
    
    
}