CSS is cached, but I have never had an issue adjusting heights and such in it. Here is the correct procedure, and what in the heck are you saving them as if your just adjusting height and stuff.
1. Do not attempt to change heights for these items in templates/base/general.css as it will just be overruled by the templates/tmpl_{tmpl}/general.css file as that one has higher priority or even get overwritten by file specific, here's the order it will call css to build a page, we'll use the home page as an example.
Called 1st, lowest priority: templates/base/css/general.css
Called 2nd, 2nd lowest priority: templates/tmpl_{tmpl}/css/general.css
Called 3rd, 2nd highest priority: templates/base/css/index.css (Note, this has the page name on the css file)
Called 4th, highest priority: templates/tmpl_{tmpl}/css/index.css (This page will dominate all others, you can use it to create a page that will look and feel totally different than all others on your site, change colors, layout, blow apart width limitations and many other things, this is the funnest of all the files as it's the most pliable and has NO effect on any other pages on your site, only the page it refers to)
So, in your case, if you want to change the height of a block that is called site wide, you can then do it in templates/tmpl_{tmpl}/css/general.css You can pull/copy strings from any file and import them into the index.css file, profile_view.css and so on to control items page specific that are normally controlled by the general.css file.
**Quick note I forgot: Have you gone to Admin => Settings => Advanced and changed the template it's calling?