later Animation

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css-

body {
  background: #323641;
}

.letter-image {
  position: absolute;
  top: 50%;
  left: 50%;
  width: 200px;
  height: 200px;
  -webkit-transform: translate(-50%, -50%);
  -moz-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
  cursor: pointer;
}

.animated-mail {
  position: absolute;
  height: 150px;
  width: 200px;
  -webkit-transition: .4s;
  -moz-transition: .4s;
  transition: .4s;
  
  .body {
    position: absolute;
    bottom: 0;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 0 0 100px 200px;
    border-color: transparent transparent #e95f55 transparent;
    z-index: 2;
  }
  
  .top-fold {
    position: absolute;
    top: 50px;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 50px 100px 0 100px;
    -webkit-transform-origin: 50% 0%;
    -webkit-transition: transform .4s .4s, z-index .2s .4s;
    -moz-transform-origin: 50% 0%;
    -moz-transition: transform .4s .4s, z-index .2s .4s;
    transform-origin: 50% 0%;
    transition: transform .4s .4s, z-index .2s .4s;
    border-color: #cf4a43 transparent transparent transparent;
    z-index: 2;
  }
  
  .back-fold {
    position: absolute;
    bottom: 0;
    width: 200px;
    height: 100px;
    background: #cf4a43;
    z-index: 0;
  }
  
  .left-fold {
    position: absolute;
    bottom: 0;
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 50px 0 50px 100px;
    border-color: transparent transparent transparent #e15349;
    z-index: 2;
  }
  
  .letter {
    left: 20px;
    bottom: 0px;
    position: absolute;
    width: 160px;
    height: 60px;
    background: white;
    z-index: 1;
    overflow: hidden;
    -webkit-transition: .4s .2s;
    -moz-transition: .4s .2s;
    transition: .4s .2s;
    
    .letter-border {
      height: 10px;
      width: 100%;
      background: repeating-linear-gradient(
        -45deg,
        #cb5a5e,
        #cb5a5e 8px,
        transparent 8px,
        transparent 18px
      );
    }
    
    .letter-title {
      margin-top: 10px;
      margin-left: 5px;
      height: 10px;
      width: 40%;
      background: #cb5a5e;
    }
    .letter-context {
      margin-top: 10px;
      margin-left: 5px;
      height: 10px;
      width: 20%;
      background: #cb5a5e;
    }
    
    .letter-stamp {
      margin-top: 30px;
      margin-left: 120px;
      border-radius: 100%;
      height: 30px;
      width: 30px;
      background: #cb5a5e;
      opacity: 0.3;
    }
  }
}

.shadow {
  position: absolute;
  top: 200px;
  left: 50%;
  width: 400px;
  height: 30px;
  transition: .4s;
  transform: translateX(-50%);
  -webkit-transition: .4s;
  -webkit-transform: translateX(-50%);
  -moz-transition: .4s;
  -moz-transform: translateX(-50%);
  
  border-radius: 100%;
  background: radial-gradient(rgba(0,0,0,0.5), rgba(0,0,0,0.0), rgba(0,0,0,0.0));
}

  .letter-image:hover {
    .animated-mail {
      transform: translateY(50px);
      -webkit-transform: translateY(50px);
      -moz-transform: translateY(50px);
    }
    
    .animated-mail .top-fold {
      transition: transform .4s, z-index .2s;
      transform: rotateX(180deg);
      -webkit-transition: transform .4s, z-index .2s;
      -webkit-transform: rotateX(180deg);
      -moz-transition: transform .4s, z-index .2s;
      -moz-transform: rotateX(180deg);
      z-index: 0;
    }
    
    .animated-mail .letter {
      height: 180px;
    }
    
    .shadow {
      width: 250px;
    }
  }

---------------------------------------------------------
html-

<div class="letter-image">
  <div class="animated-mail">
    <div class="back-fold"></div>
    <div class="letter">
      <div class="letter-border"></div>
      <div class="letter-title"></div>
      <div class="letter-context"></div>
      <div class="letter-stamp">
        <div class="letter-stamp-inner"></div>
      </div>
    </div>
    <div class="top-fold"></div>
    <div class="body"></div>
    <div class="left-fold"></div>
  </div>
  <div class="shadow"></div>
</div>