#pc_door p{
  font-size: 90px;
  padding-top: 100px;
}
span.a{


}
span.b{


}
span.c{


}

div#st_button{
  position: absolute;
  top: 800px;
  left: 50%;
  display: block;
  width: 300px;
  height: 80px;
  border: 2px solid #000;
  border-radius: 20px;
  background: #000;
  color: #fff;
  font-size: 30px;
  transform: translateX(-50%);
  text-align: center;
}