Do modern browsers care about the DOCTYPE?
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If you use deprecated attributes or tags `<center>`, `<font color="red">`, or `<td valign="top">` etc. in XHTML 1.0 Strict (no depr. attributes), modern browsers (I will use Chrome as an example) still take notice of and use them.

If you use HTML5 `<video>` on an XHTML 1.0 Strict DOCTYPE Chrome will still recognize it - it's not as if they'd program it to not. I tested the **worst** deprecated, capitalized, and unquoted attribute code I could write, along with HTML5 audio, with the XHTML 1.0 Strict DOCTYPE in Chrome and it rendered flawlessly.

Here's the code I tested, working flawlessly in Chrome (red bg, centered table, audio playing):

    <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
       "http://www.w3.org/TR/html4/strict.dtd">
    <html>
    <head>
    <title>Do browsers care about the DOCTYPE?</title>
    <meta http-equiv="Content-Type" content="text/html;charset=utf-8" >
    </head>
    <body bgcolor=#ff0000>
     <CENTER>
      <table cellpadding="0" cellspacing=0>
       <tr><td valign=top>test</td></tr>
      </table>
     </CENTER>
     and some HTML5 audio..
     <audio autoplay>
      <source src="http://www.duncannz.com/resources/sound/alarm.mp3" type="audio/mp3">fallback text</audio>
    </body>
    </html>
<br>
So my question: Do modern browsers (translation: browsers other than IE) pay *any* attention at all, or do *anything* differently, because of the DOCTYPE? Do they even bother to read and interpret it?