How to dynamically constrain amount of Text/Content in a DIV


Can anyone recommend how best to how to dynamically constrain amount of
Text/Content in a DIV area that can vary in size??

That is, say you have:
(a) a content (DIV) area on your view that can expand/contract depending
upon browser size (i.e. when someone is re-sizing the browser window)
(b) dynamic text/content that is to be displayed, based upon user input

e.g. image a defined area/size for several user comments for example.
can create their own comments, but you only want them to be able to take
a given amount of screen resource, and then perhaps have a “…more”
link at
the bottom if they go over.

How can I best setup this in Rails? e.g.
(1) How to setup the layout/CSS so that if more text / content is
present in
the DIV area that can be displayed that the DIV area doesn’t expand due
the extra content the user put forward, and/or
(2) How to calculate how much text/content can fit in the current size
the DIV (noting browser re-sizing) so that you get the chance to put the
“…more” link at the bottom?

Any other suggestions welcome that address what I’m trying to do are
welcome, which is really offering a area for display of user feedback
each piece of feedback has a maximum area it can take on the main screen
only, and also that browser re-sizing is possible.