.site-footer {
    width: 100%;
    height: 1.7rem;
    background: #222;
    color: #fff;
    text-align: center;
    padding: 0.3rem 0;
    position: fixed;
    left: 0;
    bottom: 0;
    z-index: 200;
    box-shadow: 0 -2px 8px rgba(0,0,0,0.08);
}

.site-footer ul {
  display: flex;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  
}

.site-footer ul li {
  list-style: none;
  margin: 0.5rem;
  line-height: 1.7rem;

}

.site-footer ul li a {
  margin: 0;
  padding: 0.3rem;
  width: 0.8rem;
  height: 0.8rem;
  background-color: #fff;
  text-align: center;
  line-height: 0.8rem;
  font-size: 0.6rem;
  display: block;
  border-radius: 50%;
  position: relative;
  overflow: hidden;
  border: 3px solid #fff;
  z-index: 1;
  box-shadow: -2px 2px 10px rgba(0, 0, 0, 0.15);
}

.site-footer ul li a .icon {
  position: relative;
  color: #262626;
  transition: .5s;
  z-index: 3;
}

.site-footer ul li a:hover .icon {
  color: #fff;
  transform: rotateY(360deg);
}

.site-footer ul li a:before {
  content: "";
  position: absolute;
  top: 100%;
  left: 0;
  width: 100%;
  height: 100%;
  background: black;
  transition: .5s;
  z-index: 2;
}

.site-footer ul li a:hover:before {
  top: 0;
}

.site-footer ul li:nth-child(2) a:before{
  background: #3b5999;
}

.site-footer ul li:nth-child(3) a:before{
  background: #7785cc;
}

.site-footer ul li:nth-child(4) a:before {
  background: #0077b5;
}

.site-footer ul li:nth-child(5) a:before {
  background: black;
}