body {
  background-position: center;
  background-color: #3A539B;
  font-size: 16px;
  margin: 0 auto;
  padding: 0px;
  font-family: "Microsoft YaHei",arial,sans-serif;
}

#download {
  position: absolute;
  top: 50%;
  left: 50%;
  margin-top: -180px;
  margin-left: -280px;
  width: 560px;
  padding: 40px;
  border-radius: 10px;
  background-color: #ecf0f1;
  opacity: 0.85;
  -webkit-box-shadow: 0px 0px 25px -1px rgba(0,0,0,0.75);
  -moz-box-shadow: 0px 0px 55px -10px rgba(0,0,0,0.75);
  box-shadow: 0px 0px 55px -10px rgba(0,0,0,0.75);
}

.text-center {
  text-align: center;
}

.active {
  list-style: 
}

a {
  color: #3A539B;
  text-decoration: none;
}

a:hover {
  color: #1E8BC3;
  text-decoration: underline;
}

@media screen and (max-width: 768px) {
  #download {
    top: 30%;
    left: 0;
    margin-top: 0px;
    margin-left: 0px;
    width: 100%;
    padding: 0px;
  }
}