What does the code: .\31 u\24 mean?

Question

css

What does the code: .\31 u\24 mean? And how is it created?
Compiled via SASS, if so, how?

Answer 1

This is simple escaping, escaping special characters. or invalid characters.
In CSS, a class can only start with the characters "az, _, -"
But in html, you can write anything.
So you can do this

.\31 {}
.\@md-3

<div class="31"></div>
<div class="@md-3"></div>

This has nothing to do with sass. pure css.

Answer 2

<a href=\x22#\x22 id=\x22
----------------
Maybe like a replacement?

Answer 3

This is unicode.
i.e.
More details here https://mathiasbynens.be/notes/css-escapes