.box {
 position:relative;
 
 width: 149px; 
 float:left;
 height:20px;
}
.appear{
    background:lightgray;
    position:absolute;
    height:145px;
    width:300px;
    display:none;
    z-index:9999;
    transition:all 0.3s ease;
    -moz-transition:all 0.3s ease;
    -o-transition:all 0.3s ease;
    -webkit-transition:all 0.3s ease;
}

.box:hover .appear {
    
   
    left:0;
   
}