button{
    outline: none;
    position: relative;
    cursor: pointer;
    display: block;
    text-align: center;
    border: 5px solid #ff7b7b;
    border-radius: 50%;
    box-shadow: 0 0 3px rgba(0,0,0,.8);
    padding: 0;
    width: 100px;
    height: 100px;
    color: #FFF;
    background-color: #df4545;
    font-family: sans-serif;
    font-size: 16px;
    font-weight: 700;
    line-height: 1;
    transition: all .3s ease;
}

button:focus,
button:hover{
    background-color: #ed4f4f; 
    box-shadow: 0 0 10px rgba(0,0,0,.5);
}