SASS language violation

[galaxy4public]

responsive-tools/src/_breakpoints.scss

Line 36 in cc4937e

@if (str-slice($query, 0, 2) == '>=') {

On the above line the call to str-slice uses 0 as the index argument, while the language specification explicitly says that index starts at 1: http://sass-lang.com/documentation/Sass/Script/Functions.html#str_slice-instance_method

Note that unlike some languages, the first character in a Sass string is number 1, the second number 2, and so forth.

All SASS/SCSS compilers I tried locally are refusing to work with this file complaining about the index.