Is CSS content property SEO friendly?

Question

Is CSS content property bad from SEO point of view, do search engines really scan the words which are injected using :before and :after selectors?

Take this example :

Mr.A uses CSS content property to embed the question tag in h1, so my question is do search engines scan that word in my h1 tag? am pretty much sure they don't.

Demo

<h1 class="CSS">Pure CSS Menu</h1>
<h1 class="HTML">Structure And Symantics</h1>

.CSS:before {
    content: 'CSS : ';
}

.HTML:before {
    content: 'HTML : ';
}

Answer 1

No, search engines do not care about what you put inside your css, js, alt tags, or even meta tags (keywords) as far as "positive" rankings go.

They will however try to detect if you are injecting spam, settings h1's with hidden keywords to display:none, setting a white background on white text, etc.

So ..anything not related to pure content, url & title can work against you, but never for you (some blackhats might not agree..).