Applying CSS styles only to certain elements

Question

I have an existing website with lots of old pages and forms laid out with tables which I am trying to gradually transition to CSS. I want to use the Twitter Bootstrap stylesheets - particularly the styles for forms - but only on sections of pages where I have explicitly requested them. For example, I might surround the whole form in a div like so:

<div class="bootstrap">  <!-- everything in here should have the Bootstrap CSS applied -->  <form>    <p><label for="text_input">Label</label><input type="text" id="text_input" /></p>  </form> </div> 

I want all other forms to remain the same as they are now, because I won't be able to change them all at the same time. Is there a simple way to do this? I could go through every single style in the Bootstrap CSS and add a parent selector (e.g. 'p' would become 'div.bootstrap p'), but that would take a long time and it would be easy to miss styles.

Edit: If such a thing isn't possible, is there a free tool which can extract all the styles from a file, add a prefix and then save them back again?

Answer 1

For Bootstrap 3, it's easier if you use less:

Download the Bootstrap source code and make a style.less file like this:

.bootstrap {     @import "/path-to-bootstrap-less.less";     @import "/path-to-bootstrap-responsive-less.less"; } 

Finally, you have to compile the less file; there are many alternatives

https://github.com/cloudhead/less.js/wiki/Command-Line-use-of-LESS https://github.com/cloudhead/less.js/wiki/GUI-compilers-that-use-LESS.js

Or use npm to install less then compile the style.less file to style.css:

npm install -g less lessc style.less style.css