Google says that "Hiding text or links in your content can cause your site to be perceived as untrustworthy since it presents information to search engines differently than to visitors. [...]

Hidden links are links that are intended to be crawled by Googlebot, but are unreadable to humans. [...]

If your site is perceived to contain hidden text and links that are deceptive in intent, your site may be removed from the Google index, and will not appear in search results pages."

So this is how my website www.neoteccomputer.com
would look if I used HTML to hide it: Neotec Computer
The SEO value drops dramatically when you convert this.