Hello
Need assessment for Form validation tasks.
Codepen:
Welcome back, @VladimirK
I really like how you did additional work to create a great styling. 
Here are my comments:
<samp> is generally used for output of a computer program. I think a good way to show the tel number hint would be using the placeholder attribute. Modern screen readers also read out the placeholder attribute as far as I know.^ and $ aren’t necessary.[A-Za-z0-9]+
[-. ] as the separator. (I recommend putting the dash at the start or end. This avoids using it accidentally as range operator)Have a nice weekend,
Michael
@mikoMK, thank you! About <samp>. I guided from this article about dark side of placeholder attribute.
Thanks for the article. That was a very interesting read.
It seems there are a lot of reasonable arguments speaking against the placeholder attribute. Therefore I think Eric’s (and your) approach is a good solution to this. I’m still a bit unsure about the use of <samp> but I also don’t know of a better fitting tag and it’s probably better than using a generic <span> with some styling.
Thanks again and stay safe.