Breaking Change: abs() Percentage
Sass has historically supported the abs() function. After CSS supported calculations in Values and Units Level 4, we had to workaround backwards-compatibility. However, for the abs() function we posses a compatibility problem supporting the % unit.
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.
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.
For this reason, we are deprecating the global abs() function with a percentage.
To preserve the current behavior, use math.abs() instead.