Transparent background for Facebook "like" button

I need the background for the Facebook "like" button to be transparent.

I've achieved this one time but I don't remember how I did it.

allowTransparency="true" in the iframe version of the button does开发者_StackOverflow中文版n't work either.

Any ideas?

allowTransparency="true" with iframe version should work, I have used it recently without any problem like this:

<iframe src="//www.facebook.com/plugins/like.php?app_id=242000359180192&amp;href=www.facebook.com%2Fbevagus&amp;send=false&amp;layout=button_count&amp;width=180&amp;show_faces=true&amp;action=like&amp;colorscheme=dark&amp;font&amp;height=21&amp;locale=cs_CZ" scrolling="no" frameborder="0" style="border:none; overflow:hidden; width:180px; height:21px;" allowTransparency="true"></iframe>