button{
    outline: none;
    cursor: pointer;
    display: block;
    text-align: center;
    border: none;
    background-color: #647389;
    color: #FFF;
    padding: 0;
    width: 6em;
    height: 6em;
    font-family: sans-serif;
    font-size: 16px;
    font-weight: 700;
    line-height: 1.3;
    letter-spacing: .3em;
    text-transform: uppercase;
    box-shadow: 0 0 5px rgba(0,0,0,.4);
    transition: all .3s ease;           
}

button:focus,
button:hover{
    color: #89c3ec;
    box-shadow: 0 0 10px rgba(0,0,0,.7);
}