Flex Example

HTML

<div class="container">
    <div>Div 1</div>
    <div>Div 2</div>
    <div>Div 3</div>
    <div>Div 4</div>
</div>

CSS

.container {
   border: 1px solid green;
   padding: 20px;
   display: flex;
   flex-direction: column;
}

.container > div {
    border: 1px solid black;
    background: #ddd;
    padding: 20px;
    margin:10px;
    flex: 1;
    overflow: hidden;
    resize: vertical;
}