.btn{
 text-align:center;
 margin:0 auto;
}
.btn-square {
  display: inline-block;
  padding: 0.5em 1em;
  text-decoration: none;
  background:#FF4500;/*????*/
  color: #FFF;
  border-bottom: solid 4px #800000;
  border-radius: 3px;
}
.btn-square:active {
  /*?????????*/
  -webkit-transform: translateY(4px);
  transform: translateY(4px);/*????*/
  border-bottom: none;/*????*/
}

.btn-circle-border-simple4:hover {
  background: #CD5C5C;
}

.btn-circle-border-simple1 {
  display: inline-block;
  text-decoration: none;
  color: #9933FF;
  width: 100px;
  height: 100px;
  line-height: 100px;
  border-radius: 50%;
  border: solid 2px #9933FF;
  text-align: center;
  overflow: hidden;
  font-weight: bold;
  transition: .4s;
}

.btn-circle-border-simple1:hover {
  background: #CC99FF;
}

.btn-circle-border-simple2 {
  display: inline-block;
  text-decoration: none;
  color: #003366;
  width: 100px;
  height: 100px;
  line-height: 100px;
  border-radius: 50%;
  border: solid 2px #003366;
  text-align: center;
  overflow: hidden;
  font-weight: bold;
  transition: .4s;
}

.btn-circle-border-simple2:hover {
  background:#3399FF ;
}

.btn-circle-border-simple3 {
  display: inline-block;
  text-decoration: none;
  color:#00CC00 ;
  width: 100px;
  height: 100px;
  line-height: 100px;
  border-radius: 50%;
  border: solid 2px #00CC00;
  text-align: center;
  overflow: hidden;
  font-weight: bold;
  transition: .4s;
}

.btn-circle-border-simple3:hover {
  background: #66FF66;
}

.btn-circle-border-simple4 {
  display: inline-block;
  text-decoration: none;
  color:#8B0000 ;
  width: 100px;
  height: 100px;
  line-height: 100px;
  border-radius: 50%;
  border: solid 2px #8B0000;
  text-align: center;
  overflow: hidden;
  font-weight: bold;
  transition: .4s;
}

.btn-circle-border-simple4:hover {
  background: #CD5C5C;
}