mirror of
https://github.com/danog/sass-site.git
synced 2024-12-12 09:29:58 +01:00
53 lines
2.9 KiB
Markdown
53 lines
2.9 KiB
Markdown
---
|
|
title: Sass and Browser Compatibility
|
|
author: Natalie Weizenbaum
|
|
date: 2017-02-10 17:46:00 -8
|
|
---
|
|
|
|
One of the core design principles of Sass has always been to **understand CSS as
|
|
little as possible**. As a CSS preprocessor of course we have to understand the
|
|
syntax of CSS, but as much as we can we try to avoid caring about the
|
|
*semantics*—the meaning behind the styles. This means that Sass has no idea
|
|
which properties are valid, which HTML elements actually exist, or even to a
|
|
large extent what the syntax of most @-rules is.
|
|
|
|
We get a lot of benefit from this. The less built-in knowledge Sass has about
|
|
CSS, the less likely it is to work poorly with new CSS features. Imagine having
|
|
to file a feature request every time you want to use a new CSS property—that
|
|
would suck! Instead, older versions of Sass will happily keep working unless the
|
|
actual *syntax* changes, which is much rarer.
|
|
|
|
Because of this decoupling, we've never needed to worry much about browser
|
|
compatibility. Sass just passes whatever CSS its given on through. It's up to
|
|
the user to determine what works where, which gives them a lot of flexibility
|
|
and gives us designers one fewer tough decision to make.
|
|
|
|
But despite this general policy, there are always a few cases where CSS
|
|
knowledge turns out to be necessary. A big one is `@extend`, which needs to know
|
|
a lot about the meaning of selectors to properly unify them and weed out
|
|
duplicates. Property values sometimes require semantic knowledge as well—we have
|
|
to know how to interpret colors, for example.
|
|
|
|
One of those cases has leapt up to bite us. Long ago, we made the decision to
|
|
always emit transparent colors as the keyword `transparent`, because it was
|
|
supported on IE6 through 8 and the alternative `rgba()` syntax was not. But it
|
|
turns out that the opposite is true for more recent versions: in IE10, `:hover`
|
|
styles aren't triggered for elements with `background-color: transparent` but
|
|
they are with `background-color: rgba(0, 0, 0, 0)`. Thanks, IE!
|
|
|
|
So we were faced with a dilemma. Keep the existing behavior which was compatible
|
|
with old outdated browsers that no one uses, or choose a new behavior that works
|
|
better with modern browsers? The choice was pretty clear: we decided to always
|
|
emit `rgba(0, 0, 0, 0)`.
|
|
|
|
In addition, we wanted to come up with a general rule to guide us in determining
|
|
which browsers we were willing to consider outdated, and which we would continue
|
|
to support (whatever that meant for the behavior in question). We decided that
|
|
if a change would negatively affect less than 2% of the global market share of
|
|
browsers according to [StatCounter GlobalStats](http://gs.statcounter.com/), we
|
|
were willing to make it.
|
|
|
|
This limit isn't set in stone. We reserve the right to change it in the future,
|
|
and to make individual decisions that may affect more browsers. But this is the
|
|
general guideline we're paying attention to, and we wanted you all to know.
|