W3C & CSS Validation

I’m trying to validate my blog, and i’ve detected a bunch of CSS validation failures from this plugin.

You can see it trying to validate my page about iPhone (in Spanish).

As i can see, lot of errors comes from filter (a fix for older iE versions, but there’s more errors. Can you upload a fixed version?

And, also, it’s the plugin still mantained?

https://www.ads-software.com/plugins/follow-button-for-feedburner/