.square_btn{
    position: relative;
    display: inline-block;
    font-weight: bold;
    padding: 0.25em 0.5em;
    text-decoration: none;
    color: #00BCD4;
    background: #ECECEC;
    transition: .4s;
  }

.square_btn:hover {
    background: #00bcd4;
    color: white;
}