W3Schools Tryit Editor

<!doctype html>
<html>

<body>
<h1>The gap Property with grid</h1>
<p>Use the <em>gap</em> property to specify the size of the gap between the rows and the columns.</p>
<p>This grid has a 20px gap between the rows, and a 50px gap between the columns:</p>
<div id="grid-container">
 <div>1</div>
 <div>2</div>
 <div>3</div> 
 <div>4</div>
 <div>5</div>
 <div>6</div>
 <div>7</div> 
 <div>8</div> 
</div>
</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/cssref/tryit.php?filename=trycss_gap2">(->オリジナル)</a>
/ <label>アドレス: <input type="text" name="naked_post_url" value="https://www.w3schools.com/cssref/tryit.php?filename=trycss_gap2" 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>