I heard that styling
<strong> tag with css (for example to make in in normal font weight) could lead to penalties in ranking.
I am wondering if I can css styles
<abbr> tag without be penalized in SEO (Google)?
Styling any tag in an attempt to manipulate SEO performance is a bad thing.
Styling any tag so it looks nice on your page is not a bad thing.
Basically, the rule is - if you are putting keywords in
<h1> (or even
<abbr>) tags and then reducing the visual emphasis of these through CSS, and then using other words in whatever takes the place of these tags in the actual design of your site, then you're running the risk of being penalised by search engines.