Change table color

[Gray Matter]

There are two things wrong with your conditional.

1) Since you're using it inside a post, you need $post instead of $userinfo.
2) You need to use the title of the option for the menu.

So your code should look like this:

<if condition="$post['field20'] == 'Female'">class="tgender_female"<else /> class="thead"</if>