重大变化：abs() 百分比
Sass 历来支持 abs() 函数。CSS 支持第 4 级值和单位计算后，我们必须解决向后兼容性问题。然而，对于 abs() 功能，我们在支持 % 单元时存在兼容性问题。
Sass 中的 abs() 全局函数支持 % 单元作为输入，并且会在解析 % 值之前解析 abs() 函数。例如，如果输入是 abs(10%)，则函数将返回 10%。因此，如果 10% 的值代表 -50px，则该函数将返回 -50px。
¥The abs() global function in Sass supported the % unit as an input and would
resolve the abs() function before resolving the % value. For instance, if
the input was abs(10%) the function will return 10%. As a result, if the
value of 10% represented -50px the function would return -50px.
但是，CSS abs() abs 函数将在解析该函数之前解析 %。因此，如果 10% 的值代表 -50px，则 abs(10%) 将返回 -10%，在浏览器中将返回 50px。
¥However, the CSS abs() abs function will resolve the % before resolving the
function. Therefore if the value of 10% represented -50px, abs(10%) would
return -10% which in the browser would be 50px.
出于这个原因，我们不推荐使用带有百分比的全局 abs()函数。要保留当前行为，请改用 math.abs()。
¥For this reason, we are deprecating the global abs() function with a percentage.
To preserve the current behavior, use math.abs() instead.
Can I Silence the Warnings?Can I Silence the Warnings? permalink
Sass provides a powerful suite of options for managing which deprecation warnings you see and when.
Terse and Verbose ModeTerse and Verbose Mode permalink
By default, Sass runs in terse mode, where it will only print each type of deprecation warning five times before it silences additional warnings. This helps ensure that users know when they need to be aware of an upcoming breaking change without creating an overwhelming amount of console noise.
If you run Sass in verbose mode instead, it will print every deprecation
warning it encounters. This can be useful for tracking the remaining work to be
done when fixing deprecations. You can enable verbose mode using
the --verbose flag on the command line, or
the verbose option in the JavaScript API.
⚠️ Heads up!
When running from the JS API, Sass doesn’t share any information across
compilations, so by default it’ll print five warnings for each stylesheet
that’s compiled. However, you can fix this by writing (or asking the author of
your favorite framework’s Sass plugin to write) a custom Logger that only
prints five errors per deprecation and can be shared across multiple compilations.
Silencing Deprecations in DependenciesSilencing Deprecations in Dependencies permalink
Sometimes, your dependencies have deprecation warnings that you can’t do
anything about. You can silence deprecation warnings from dependencies while
still printing them for your app using
the --quiet-deps flag on the command line, or
the quietDeps option in the JavaScript API.
For the purposes of this flag, a "dependency" is any stylesheet that’s not just a series of relative loads from the entrypoint stylesheet. This means anything that comes from a load path, and most stylesheets loaded through custom importers.
Silencing Specific DeprecationsSilencing Specific Deprecations permalink
If you know that one particular deprecation isn’t a problem for you, you can
silence warnings for that specific deprecation using
the --silence-deprecation flag on the command line, or
the silenceDeprecations option in the JavaScript API.