@import url(https://fonts.googleapis.com/css?family=Open+Sans:700,400);
.frame {
    position: absolute;
    top: 50%;
    left: 50%;
    width: 400px;
    height: 400px;
    margin-top: -200px;
    margin-left: -200px;
    border-radius: 2px;
    box-shadow: 1px 2px 10px 0px rgba(0, 0, 0, 0.3);
    overflow: hidden;
    background: #34495E;
    color: #fff;
    font-family: 'Open Sans', Helvetica, sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

.center {
    position: absolute;
    top: 50%;
    left: 50%;
    -webkit-transform: translate(-50%, -50%);
    transform: translate(-50%, -50%);
}

.hiddenKey {
    width: 220px;
    height: 50px;
    box-shadow: 2px 4px 8px 0 rgba(0, 0, 0, 0.3);
    -webkit-perspective: 250px;
    perspective: 250px;
}
.hiddenKey .inputWrapper {
    position: absolute;
    z-index: 2;
    -webkit-transform-style: preserve-3d;
    transform-style: preserve-3d;
    -webkit-transform-origin: 50% 0;
    transform-origin: 50% 0;
    -webkit-transition: all .5s ease-in-out;
    transition: all .5s ease-in-out;
}
.hiddenKey .inputWrapper.valid {
    -webkit-transform: rotateX(180deg);
    transform: rotateX(180deg);
}
.hiddenKey .inputWrapper.valid ~ .keyWrapper {
    box-shadow: 2px -50px 8px 0 rgba(0, 0, 0, 0.3);
}
.hiddenKey .inputWrapper .input {
    box-sizing: border-box;
    -webkit-appearance: none;
    -moz-appearance: none;
    appearance: none;
    border: none;
    border-radius: 0;
    outline: none;
    background: #fff;
    width: 220px;
    height: 50px;
    line-height: 20px;
    padding: 15px 0;
    font-size: 16px;
    color: #34495E;
    text-align: center;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    z-index: 2;
}
.hiddenKey .inputWrapper .backSide {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    font-weight: 700;
    color: #34495E;
    text-align: center;
    line-height: 50px;
    background: #fff;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    -webkit-transform: rotateX(-180deg);
    transform: rotateX(-180deg);
}
.hiddenKey .keyWrapper {
    width: 220px;
    height: 50px;
    background: #64C760;
    color: #fff;
    font-size: 16px;
    line-height: 50px;
    text-align: center;
    -webkit-transition: all .5s ease-in-out;
    transition: all .5s ease-in-out;
    box-shadow: 2px 0px 8px 0 rgba(0, 0, 0, 0);
}