Convert Cart total/subtotal CSS colors to vars

[gregdaynes]

This is for issue #2251

Following up on the feedback for #1708, I've taken Martin's suggestion for a variable name, but opted for underscores to match the rest of the variable names.

I've also opted to not use $product_price_text_color for the text - It would make it default to black, which is not inline with the current style, as well is not a fitting name for the context. Instead I've created a new var $cart_total_text_color and assigned it white.

[kennyadsl]

Thanks, all choices makes sense to me. What about indenting that block of variables with values aligned as the rest of the file?

[tvdeyen]

LGTM.

I think indentation is alright and we should start to not do these things anymore. We don’t want diffs for a huge chunk of code just because we introduced a longer variable name. Rails recently stopped this in schema files as well.

[kennyadsl]

@tvdeyen I generally agree with not using extra spaces for indentation (I'm also in favor of commas in last element of arrays and hashes to preserve git history). In this case I'd go with being consistent with the rest of the file, since I can't see an easy solution for the current state of the file: I don't think we'll change that file so often to bring it into an ideal indentation state and probably it will be completely changed in the future instead.

Of course this is a non blocking comment and I'm perfectly fine with the current indentation. 👍