So what's 'new' about this

[Yoshihama]

There are already a lot of systems that do things like CSS variable,
functions, etc., with SASS probably the most widespread. What's new
and different about Closure Style Sheets? Or is the wheel being
reinvented yet again (with the obligatory cross-system
incompatibilities that will make switching hard)?

[Objelean Alex]

I'm also curious why closure stylesheet library didn't reuse the LESS or SASS syntax, since it is already well known and widespread.

[Michael Bolin]

What's new/distinct about Closure Stylesheets as compared to LESS/SASS
(AFAICT from reading their docs):

* Linting
* RTL Flipping
* Renaming

Admittedly, LESS/SASS could add support for these features. Perhaps
they will -- if so, I would also consider that a win.

As to the other points, I think that you may be misinterpreting the
perspective from which this code was open-sourced:

It's not as if Google decided they should release a LESS/SASS
competitor and decided to go and build one last month. Take a look at
the copyrights -- some of these files date back to 2005/2006. (You
don't see quite so many of the earlier copyrights because there was a
first version of GSS that was used for awhile, but has gradually been
replaced with the current version, so the old version was kept out of
this release so that the external release is cleaner and more
coherent.) That means that this project was started over five years
ago, and like other Closure Tools, was developed directly in response
to the needs of Google projects. Originally, I believe the goal was
mainly CSS minification, but later projects, such as themes in Gmail
(http://gmailblog.blogspot.com/2008/11/spice-up-your-inbox-with-colors-
and.html) shifted the demands of Closure Stylesheets.

So in response to your comments:
* The wheel isn't being reinvented: it's just that Google's version of
the wheel is only being released now, but was invented awhile ago.
* I believe that Google's version didn't reuse the LESS or SASS syntax
because it wasn't around/dominant in 2005/2006. Also, I believe that
GSS tries harder to obey the grammar of CSS (though I think that
@mixin is an exception). The ways that functions/variables appear to
work in LESS/SASS seem to be a bigger deviation from standard CSS.

I hope that answers your questions,
Michael

[Kyaw]

To me, GSS provide coherent build process among JS and CSS files,
especially class naming.