How do I know it's quirk mode?

Is there a way to tell if it's quirk mode

[flashfan]

When browser renders a page, if there are problems, it may render it with quirk mode. How can I know if this happens? Thanks.

[bcolflesh]

If you use Firefox, the Web Developer extension shows Quirks mode on/off via a checkmark on the right:

[chrispederick.com...]

[dlefree]

The W3C validator should be able to help with determining whether or not a page is displaying in quirks mode (which is usually related to an invalid or missing Document Type Definition or DTD).

Check out the W3C site at W3C.org - it's a great resource.

[drhowarddrfine]

Or just make sure there is a proper doctype at the head by viewing the source.

[encyclo]

In Firefox, right-click on the page and select View Page Info. It will list the Render Mode as either Quirks Mode or Standards Compliance Mode.

[Dijkgraaf]

Like this thread is showing in Quirks Mode :)

[Robin_reala]

Favelet for IE courtesy of SuzyUK:

[webmasterworld.com ]

(where is Suzy anyway? Haven't seen her around in a while...)