Compress Craft Control Panel CSS and JS per environment
I don't think there's anything built into Craft. What I do is

{% if craft.config.devMode %}
  &lt;link rel="stylesheet" href="{{craft.config.environmentVariables['assetURL']}}css/style.css"&gt;
{% else %}
  &lt;link rel="stylesheet" href="{{craft.config.environmentVariables['assetURL']}}css/style.min.css"&gt;
{% endif %}


I use devMode to control whether or not I want the minified css, and I use grunt's cssmin task to build my minified css.