What's the term for not just being wrong, but the exact opposite of right?

I'd like to concisely (ideally, in one word) express my opinion that the styling on the "Removed permissions" and "Added permissions" text in the picture below is not just wrong, but the exact opposite of right:

For purposes of a short subject line in a bug report, I'd like to say that "permission changes are presented wrongly", but rather than wrongly, I'd like to use for emphasis a word that has additional connotations of being inverted, swapped (though swapped is perhaps wrong, because it implies that the items were once styled the other way- but they've always been like this). I'd prefer to stay away from words like 'moronic' - I want to be polite.

(for the curious, the styling is correct from the point of a computerised diff, where green typically denotes additions and red deletions - but wrong from the point of view of user-experience and security, because the most dangerous items are styled with green, and the least dangerous with red, opposite to conventional warning design)

You could say these were antithetical to or the antithesis of the correct thing, meaning that whatever the right thing is, what you see is diametrically opposed to that:

antithesis n
2. the direct opposite (usually followed by of or to):
Her behavior was the very antithesis of cowardly.

_{Source: dictionary.reference.com}

In your case, you might say

The styling of the permissions text is the antithesis of good UX design.

You could say "That answer is the "polar opposite" of what I'm looking for!"

backwards

'3. in the reverse of usual order or direction¹

'2. Done or arranged in a manner or order that is opposite to previous occurrence or normal use.²

The styles used for the Removed and Added permission labels are backwards.

^{1_{Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003}
2_{American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.}}

"Dead wrong" seems like an appropriate modifier to "wrong" to emphasize your point.

Diametrically opposed, where diametric in particular, as per dictionary.com:

adjective:

1. of, relating to, or along a diameter. .

2. in direct opposition; being at opposite extremes; complete: diametrical opposites; a diametrical difference.