Hover et delay en CSS

<div class="container">
  <div class="btn">Bouton hover</div>
  <div class="content">
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  </div>
</div>
.container .content{
  display:none;
  background:#300;
  padding: 50px;
  color:#FFF;
}
 
.container .btn{
  background:#F00;
  color:#FFF;
  padding: 10px 20px; 
  display:inline-block;
}
 
.container .btn:hover + .content{
  display: table; 
  -webkit-animation: hover 1s ease-in-out; 
  animation: hover 1s ease-in-out;
}
 
 
@-webkit-keyframes hover {
    0% {
        opacity: 0;
        filter: alpha(opacity = 0);
    }
    70% {
        opacity: 0;
        filter: alpha(opacity = 0);
    }
    100% {
        opacity: 1;
        filter: alpha(opacity = 100);
    }
}
@keyframes hover {
    0% {
        opacity: 0;
        filter: alpha(opacity = 0);
    }
    70% {
        opacity: 0;
        filter: alpha(opacity = 0);
    }
    100% {
        opacity: 1;
        filter: alpha(opacity = 100);
    }
}