DEPRECATION WARNING: Using / for division is deprecated

[philwilliammee]

Sass currently treats / as a division operation in some contexts and a separator in others. This makes it difficult for Sass users to tell what any given / will mean, and makes it hard to work with new CSS features that use / as a separator.

more info
https://sass-lang.com/documentation/breaking-changes/slash-div

for example replace

padding-left: ($grid-gutter-width / 2);

with

padding-left: math.div($grid-gutter-width, 2);