* {
    margin: 0;
    padding: 0;
}
body {
    width: 100vw;
    height: 100vh;
    position: relative;
    display: flex;
    justify-content: center;
    align-items: center;
    background-color: #d9afd9;
background-image: linear-gradient(0deg, #d9afd9 0%, #97d9e1 100%);
}

.card {
    width: 700px;
    height: 300px;
    background-color: #f5efe6;
    color: #334756;
    box-shadow: 0px 0px 22px 5px rgb(237, 237, 237);
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    font-size: 2.5em;
    font-family: '楷体';
    position: relative;
    /* 使盒子具备透视效果 */
    transform-style: preserve-3d;
    transform: perspective(900px) rotateX(23deg);
}
.card::before,
.card::after {
    content: '';
    width: 50%;
    height: 100%;
    color: #b7c4cf;
    font-size: 40px;
    position: absolute;
    font-family: '华文行楷';

}
.card::before {
    content: '写给宝宝的';
    left: 0;
    top: 0;
    display: flex;
    justify-content: flex-end;
    align-items: center;
    transition: 2s;
    transform-origin: left;
}
.card::after {
    content: '第一封书信';
    right: 0;
    top: 0;
    display: flex;
    justify-content: flex-start;
    align-items: center;
    transform-origin: right;
    transition: 2s;

}

.card:hover::before {
    transform: rotateY(-180deg);
}
.card:hover::after {
    transform: rotateY(180deg);
}
.content {
    opacity: 0;
    transition: 2s;
}
.card:hover .content {
    opacity: 1;
}
/* 心动效果 */
@keyframes change {
    30% {
      transform: rotate(45deg) scale(1.1) translateX(-70%);
    }
    40% {
      transform: rotate(45deg) scale(1.3) translateX(-70%);
    }
    45% {
      transform: rotate(45deg) scale(0.9) translateX(-70%);
    }
    50% {
      transform: rotate(45deg) scale(0.5) translateX(-70%);
    }
    70% {
      transform: rotate(45deg) scale(1) translateX(-70%);
    }
    80% {
      transform: rotate(45deg) scale(1.5) translateX(-70%);
    }
    90% {
      transform: rotate(45deg) scale(0.7) translateX(-70%);
    }
    95% {
      transform: rotate(45deg) scale(1.5) translateX(-70%);
    }
    100% {
      transform: rotate(45deg) scale(1.1) translateX(-70%);
    }
  } 
  .heart {
    position: absolute;
    right: 0;
    bottom: 0;
    width: 50px;
    height: 50px;
    /* pink yyds */
    background-color: pink;
    /* 往右下脚偏一些 */
    transform: rotate(45deg) translateX(-70%);
    /* 给这个爱心绑定动画 */
    /* 动画的名字 */
    animation-name: change;
    /* 动画持续时间 */
    animation-duration: 2.7s;
    /* 无限次播放动画 永远对你心动 */
    animation-iteration-count: infinite;
    cursor: pointer;


  }
/* 画爱心桃 */
.heart::before {
    content: '';
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: pink;
    position: absolute;
    transform: translateX(-25px);

}
.heart::after {
    content: '';
    width: 50px;
    height: 50px;
    border-radius: 50%;
    background-color: pink;
    position: absolute;
    transform: translateY(-25px);
}
/* 中间的字体样式有点丑  调一下 */
.text {
    color: #7D6E83;
    margin-top: 45px;
    font-family: '华文行楷';
}
.textTwo {
    color: #7D6E83;
    font-weight: bold;
    font-size: 25px;
    margin-top: 30px;
}
/* 神秘的box */
#box {
    position: absolute;
    left: 0;
    top: 0;
    z-index: -200;
    opacity: 0;
    color: #009dff;
    padding-left: 5vw;
    padding-right: 5vw;
    padding-top: 13vh;
    width: 90vw;
    height: 87vh;
    text-align: center;
    background-image: url(222.jpg);
    overflow: hidden;
    background-size: cover;
    font-size: 25px;
    font-family: '华文行楷';
    transition: opacity 7s;
}