Get value of attribute in CSS

Issue

I have this HTML code:

<div data-width="70"></div>

I want to set it's width in CSS equal to the value of data-width attribute, e.g. something like this:

div {
    width: [data-width];
}

I saw this was done somewhere, but I can't remember it. Thanks.

Solution

This is what I was looking for:

https://developer.mozilla.org/en-US/docs/Web/CSS/attr

The problem is that at this time of writing it's not supported even by some of the major browsers (in my case Chrome):

Answered By - Amar Syla