Math in breakpoint-max mixin no longer working in newer version of Sass

[jmcgaha]

After recently upgrading to gulp-sass 3.2.1 which uses node-sass 4.8.3, the math to subtract 1px no longer works leaving me things like:

max-width(48em - 0.0625em) in the processed CSS which does not work in the browser.

As a workaround I had to remove the px to em conversion for that 1px and for each breakpoint size.
Could be related to #28, but I tried some of the suggested methods and it still wasn't working.

tentcss/src/02_tools/_breakpoints.scss

Line 20 in bac3d00

$val: #{map-get($breakpoints, $breakpoint)} - em(1px);

[ulinaaron]

Thanks @jmcgaha! I'll take a look at this and see if I can get a refactor for the current version of Tent.