*,
*:before,
*:after {
    box-sizing: border-box;
    outline: none;
}

html {
    font-family: "Source Sans Pro", sans-serif;
    font-size: 16px;
    font-smooth: auto;
    font-weight: 300;
    line-height: 1.5;
    color: #444;
}

body {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 100%;
    height: 100vh;
    background: linear-gradient(45deg, #E91E63, #9C27B0);
}

code,
.card .line-numbers {
    font-family: "Lucida Console", Monaco, monospace;
    font-size: 14px;
}

.card {
    position: relative;
    width: 30rem;
    height: 15rem;
    perspective: 150rem;
}

.card-front,
.card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    margin: auto;
    border-radius: 5px;
    box-shadow: 0 1.5rem 4rem rgba(0, 0, 0, 0.4);
    transition: 0.9s cubic-bezier(0.25, 0.8, 0.25, 1);
    backface-visibility: hidden;
    overflow: hidden;
}

.card-front:before,
.card-front:after,
.card-back:before,
.card-back:after {
    position: absolute;
}

.card-front:before,
.card-back:before {
    top: -40px;
    right: -40px;
    content: "";
    width: 80px;
    height: 80px;
    background-color: rgba(255, 255, 255, 0.08);
    transform: rotate(45deg);
    z-index: 1;
}

.card-front:after,
.card-back:after {
    content: "+";
    top: 0;
    right: 10px;
    font-size: 24px;
    transform: rotate(45deg);
    z-index: 2;
}

.card-front {
    width: 100%;
    height: 100%;
    background: linear-gradient(45deg, #101010, #2c3e50);
}

.card-front:after {
    color: #212f3c;
}

.card-back {
    background: linear-gradient(-45deg, #101010, #2c3e50);
    transform: rotateX(180deg);
}

.card-back:after {
    color: #11181f;
}

.card:hover .card-front {
    transform: rotateX(-180deg);
}

.card:hover .card-back {
    transform: rotateX(0deg);
}

.card .line-numbers {
    position: absolute;
    top: 0;
    left: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100%;
    margin: 0;
    padding: 0 10px;
    background-color: rgba(255, 255, 255, 0.03);
    font-size: 13px;
}

.card .line-numbers>div {
    padding: 2.5px 0;
    opacity: 0.15;
}

.card code,
.card .line-numbers {
    color: whitesmoke;
}

.card .indent {
    padding-left: 30px;
}

.card .operator {
    color: #4dd0e1;
}

.card .string {
    color: #9ccc65;
}

.card .variable {
    color: #BA68C8;
}

.card .property {
    color: #ef5350;
}

.card .method {
    color: #29b6f6;
}

.card .function {
    color: #FDD835;
}

.card .boolean {
    color: #4dd0e1;
}