Hey @nurkka I'd second what @wbmnfktr said and recommend switching to modern css as much as possible. Or course it always depends on the situation and use case, but in general I think modern CSS is much more powerful.
For example I've developed a website for a client where we have 3 different business units which have their own color (blue/green/yellow). This is called the "primary-color". Using css variables it is possible to switch colors easily across sections, so example.com/boats is blue example.com/outdorr is green and example.com/sunsails is yellow.
So all I do is adding this:
html {
--col-primary: #ff0000;
}
Then I can use var(--col-primary) in my css and all colors will be changed.
Using CSS variables instead of LESS has many benefits, for example:
It will work with only one CSS file. The color will be set in the HTML. Using LESS you can only set @col-primary to ONE value. That means you'd have to create main-blue.css, main-green.css and main-yellow.css
Using CSS variables it is even possible to set different colors for different sections on the page. For example on the frontpage we can show blog posts from all sections and depending on the section they belong to we can set a different color. But all cards will use the same CSS. All you have to do is this:
<h2>Blog posts boats</h2>
<div style='--col-primary: blue'> ... </div>
<h2>Blog posts outdoor</h2>
<div style='--col-primary: green'> ... </div>
<h2>Blog posts sunsails</h2>
<div style='--col-primary: yellow'> ... </div>
This is very powerful and not possible in LESS/SCSS.
I'm still using LESS for convenience, for example for RockPageBuilder it is still nice to have, because I can "namespace/scope" css via nesting, so that added css does not mess with global css defined somewhere else.