less-mode

Major Emacs mode for editing Less files. Inspired by scss-mode.

Installation

(require 'less-mode)
(add-to-list 'auto-mode-alist '("\\.less$" . less-mode))

If you use smart-compile:

(add-to-list 'smart-compile-alist '(less-mode . (less-compile)))

If you use Flymake, it will work automatically.