At Limesurvey 2.0 there will be an advanced export option which exports survey, template, token data and answer data as a ZIP file which can then be imported.
The according import could be extended to also replace question IDs at the CSS files when importing the template. This has to be an optional setting because usually you use one template for several surveys.

Another solution would be an CSS export/import feature which replaces IDs.

Both solutions seems good. And yes - I guess this should be optional.

I use this e.g. for some questions which have a e.g. a seven point answer scale. Then I user color gradients from green to red, as a visual aid to the respondent. (respondents give me really good feedback about this.)

Maybe this could be implemented as new custom questions types? This way I could e.g. create a specific question, save it as a new question type, with custom styling. Later I can choose this question type in new surveys...

What ever is the less hassle to implement :-)

There is no need to implement a search and replace for css

Each group and question should have the ability to add a custom class to it that would be carried through on import and would prevent the need for writing the same class many times

For example I just created a moderate survey. to get the survey to look right I had to hide javascript into the description of every group to add the required classes to the appropriate question

I then saved the survey and imported it to create a second copy that was because both surveys were very similar (different target audience)

I was stunned to find the questions renumbered. Why? questions should be referenced by surveyid-question they should not be unique per survey!

Now I have to go through each group and redo the javascript - bummer dude.

A simple additional field could be used to add a css class to each of the required questions and this would not have been a problem. in fact it could be just a named custom field which could be inserted into the group or question using {CUSTOM-FIELDNAME} that way it would be totally flexible

I am going to report it as a feature request.

BTW lesscss would not solve the issue. you still need to identify the question somehow

I like the idea of being able to add additional CSS classes to questions. This could easily be done by an additional question attribute.

This might be implemented at the next Limesurvey 2.1 version.