body{
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100vh;
    background-color: #39A7FF
}

.birthdayCard{
    position: relative;
    width: 450px;
    height: 650px;
    cursor: pointer;
    transform-style: preserve-3d;
    transform: perspective(2500px);
    transition: 1s;
}

.birthdayCard:hover{
    transform: perspective(2500px) rotate(3deg);
    box-shadow: inset 100px 20px 100px rgb(0, 0, 0,0.2), 0 10px 100px rgb(0,0 ,0,0.6);
}

.birthdayCard:hover .cardFront{
    transform: rotateY(-160deg);
}

.birthdayCard:hover .happy{
    visibility: hidden;
}

.cardFront{
    position: relative;
    background-color: aliceblue;
    width: 450px;
    height: 650px;
    overflow: hidden;
    transform-origin: left;
    box-shadow: inset 100px 20px 100px rgb(0, 0, 0,0.2), 30px 0px 50px rgb(0,0 ,0,0.4);
    transition: 0.8s;
    border:groove black 2px;
}
.happy{
    font-family: sans-serif;
    font-size: large;
    border-radius: 10px;
    text-align: center;
    margin: 30px;
    height: 500px;
    padding-top: 10px;
    background-image: linear-gradient(120deg, #ffd856 0%, #f98c6e 100%);
    transition: 0.1s;
    border:groove black 2px;
}
.happy h1{
    color: black;
}
.cardInside{
    position: absolute;
    background-color: aliceblue;
    width: 450px;
    height: 650px;
    z-index: -1;
    left: 0;
    top: 0;;
    box-shadow: inset 100px 20px 100px rgb(0, 0, 0,0.2);
    border: groove #333 2px ;
}

p{
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    margin : 40px;
    color: grey;
}

.name{
    position: absolute;
    left: 150px;
    top: 400px;
    color: #333;
}
.back{
    font-family: Verdana, Geneva, Tahoma, sans-serif;
    color: #333;
    text-align: center;
    margin: 30px;
    outline-color: #333;
}
.hbd{
    border: #333 solid ;
    border-radius: 10px;
    width: 340px;
    transform: translateX(20px);
}
.hbd h1{
    font-family: 'Lucida Sans', 'Lucida Sans Regular', 'Lucida Grande', 'Lucida Sans Unicode', Geneva, Verdana, sans-serif;
    font-size: 30px;
}