W3Schools Tryit Editor

<!doctype html>
<html>

<body>
<h1>This heading will not be affected</h1>
<p>This paragraph will be red and center-aligned.</p>
<p>This paragraph will be red, center-aligned, and in a large font-size.</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_syntax_element_class2">(->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_syntax_element_class2" 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>