Drupal multisite: Same theme, different colors
Well, I found out something that is quite useful:

Instead of trying to import the color.less file in each 'basic' theme css file, I do it the other way around: I import all the basic theme css files in colors.less, like this:

@basis: blue;
@donker: black;
@licht: pink;

@import "../all/themes/Theme/css/basic.less";


Then I had to remove all the stylesheet definitions in the .info file and changed the template function to:

$css = drupal_add_css(conf_path() . '/colors.less', array('group' =&gt; CSS_THEME, 'weight' =&gt; 115, 'browsers' =&gt; array('IE' =&gt; 1, '!IE' =&gt; 1), 'preprocess' =&gt; FALSE));


No hassle with php, and it works, is cached when I want it, and fast!