SO 29093295

HTML

<div class="inbox">
    <div class="message">
      Message 1
     </div>
     <div class="message">
      Message 2
     </div>
     <div class="message">
      Message 3
     </div>
     <div class="message">
      Message 4
     </div> <div class="message">
      Message 5
     </div> <div class="message">
      Message 6
     </div> <div class="message">
      Message 7 - last message
     </div>
    
</div>

CSS

.inbox {
    border: 1px solid black;
    padding: 10px;
}

.message {
    height: 10px;
    border: 1px solid red;
    overflow: hidden;
}

.message:first-child {
    height: 100px;   
}

.message:last-child {
    height: 100px;   
}
}