Variables in .md are not displayed

[metamn]

I'm looking at https://github.com/hagenburger/livingstyleguide-example/blob/master/middleman-example/source/css/base/_grid.md where I see The layout is based on <var class="$columns-count"></var> Columns and I think this will display the number of columns.

However the text displayed in the browser is:
"The layout is based on Columns with width each and a gap of . Most elements can span or skip several columns."