First-child full-width in Flexbox : <p>How can I can set first-child in flexbox full-width and all of the other child set to <code>flex:1</code>(for split space)?</p>

<p>Like this:</p>

<p><a href="https://i.stack.imgur.com/bjGWl.png" rel="noreferrer"><img src="https://i.stack.imgur.com/bjGWl.png" alt="enter image description here"></a></p>
