Move <main> and .sidebar markup out of PHP and into LESS

It's always bothered me that (1) these PHP functions add markup and (2) that they specifically add *Bootstrap* markup to HTML elements.

Why not move them into LESS?
It's funny, I actually always use two spaces in my PHP but somehow got in the habit long ago of using tabs in my CSS.

Can you point me to the coding standard you prefer? Curious too because the [WordPress PHP coding standards](http://make.wordpress.org/core/handbook/coding-standards/php/) are rather dreadful imho.