Open Twitter's website and change the window size, you'll notice that layout changes responsively. Let's do something similar in this problem, suppose…

9. multi-column text

7. a row

8. Twitter's website layout

<pre class="shiki github-dark shaku"><code>.container { height: 150px; display: flex; justify-content: center;}.left { background-color: #eee; flex:0 0 40px; height: 150px; line-height: 150px; text-align: center;}.middle { background-color: #ddd; flex: 1 1; max-width: 240px; height: 150px; line-height: 150px; text-align: center;}.right { background-color: #eee; display: none; height: 150px; line-height: 150px; text-align: center;}@media (min-width:420px){ .right{ display: block; flex: 0 0 120px; }}@media(min-width:460px){ .left{ flex: 0 0 80px; }}</code></pre>