W3Schools Tryit Editor

<!doctype html>
<html>

<body>
<h2>Grid of Boxes</h2>
<p>Float boxes side by side:</p>
<div>
 <div>
 <p>Some text inside the box.</p>
 </div>
 <div>
 <p>Some text inside the box.</p>
 </div>
 <div>
 <p>Some text inside the box.</p>
 </div>
</div>
<p><strong>Note:</strong> Here, we use the clearfix hack to take care of the layout flow. 
We also use the box-sizing property to make sure that the box doesn't break due to extra padding. Try to remove this code to see the effect.</p>
</div><div class="naked_ctrl">
<form action="/index.cgi/contrast" method="get" name="gate">
<p><a href="http://altstyle.alfasado.net">AltStyle</a> によって変換されたページ <a href="https://www.w3schools.com/css/tryit.asp?filename=trycss_float_boxes">(->オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://www.w3schools.com/css/tryit.asp?filename=trycss_float_boxes" size="22" /></label> <label>モード: <select name="naked_post_mode">
<option value="default">デフォルト</option>
<option value="speech">音声ブラウザ</option>
<option value="ruby">ルビ付き</option>
<option value="contrast" selected="selected">配色反転</option>
<option value="larger-text">文字拡大</option>
<option value="mobile">モバイル</option>
</select>
<input type="submit" value="表示" />
</p>
</form>
</div>		
</body>
</html>