Pure css material button click

button.css

.btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate3d(-50%, -50%, 0);
    padding: 1em 2em;
    background-color: #3498db;
    border-radius: 3px;
    color: #fff;
    font-family: 'Roboto', sans-serif;
    cursor: pointer;
    overflow: hidden;
    box-shadow: 0 2px 0 #2980b9;
}

.btn:hover, .btn:focus {
    /*background-color: #27ae60;*/
}

.btn > * {
    position: relative;
}

.btn span {
    display: block;
    padding: 12px 24px;
}

.btn:before {
    content: "";

    position: absolute;
    top: 50%;
    left: 50%;

    display: block;
    width: 0;
    height: 100%;
    padding-top: 0;

    border-radius: 100%;

    background-color: rgba(236, 240, 241, .3);

    -webkit-transform: translate(-50%, -50%);
    -moz-transform: translate(-50%, -50%);
    -ms-transform: translate(-50%, -50%);
    -o-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
}

.btn:active:before {
    width: 120%;
    padding-top: 120%;
    transition: width .1s ease-out, padding-top .1s ease-out;
}