Forcing image alt text with CSS solution

I started thinking on ways to force the image 'alt' text when images are not visible and this is what I have come up with:

img[alt] {
color:#202020 !important;

It worked for me in Thunderbird for Mac.
Any improvements? I'm very curious to see how this works for Windows & Linux users.

I tweeted this to the CM and the awesome Ros Hodgekiss replied. :-)


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