.flip-box {
    perspective: 1000;
    -webkit-perspective: 1000;
    position: relative;
    width: 100%;
    height: 100%;
}
.flip-box .b {
    position: relative;
    width: 100%;
    height: 100%;
    will-change: transform;
    transition: all .5s ease-in-out;
    cursor: pointer;
    transform-style: preserve-3d;
}
.flip-box .b1, .flip-box .b2 {
    border: 1px solid #e2e2e2;
    border-radius: 10px;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    overflow: hidden;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    position: absolute;
    padding: 1.5rem;
}
.flip-box .b1 {
    background-color: #fff;
    display: -ms-flexbox;
    display: flex;
    -ms-flex-direction: column;
    flex-direction: column;
    -ms-flex-pack: justify;
    justify-content: space-between;
}
.flip-box .b1 .num {
    margin: 0;
    margin-top: auto;
    margin-left: auto;
    font-weight: 700;
    font-size: 30px;
    line-height: 30px;
    color: #003761;
}
.flip-box .b2 {
    background-color: #003761;
    color: #fff;
    transform: rotateY(180deg);
    overflow-y: auto;
}
.flip-box .b:hover {
    transform: rotateY(180deg);
}