Problem with DIV content

[CRASH_OVERRIDE]

This is kinda hard to describe, but I have a div block, with a bunch of text in it. The div is set at 100% height, and is contained by another div. The problem is that the text doesnt stay inside the div, but it continues down past it. Is there a css way arouund this?
The markup:

<div id="mainCol">
<div id="mainCol_contContainer">
<div id="mainCol_cont">CONTENT<br />a<br />a<br />a<br />a<br />a... <!-- and so on... -->
</div>
</div>
</div>

the CSS:

#mainCol { width:600px; height:100%;float:right; }
#mainCol_contContainer {
height:100%;
padding-left:5px;
padding-right:5px;
padding-bottom:5px;
background-color:#858F9B; }
#mainCol_cont {
background-color:#DAE0E6;
height:100%;
color:#333333; }

That problem is only in Mozilla.

There's also a minor problem in IE, where the left column doesnt measure up with the right one. The below link should help solve that.

Thanks in advance. :confused:

[CRASH_OVERRIDE]

This should help:
www.bgvc.net/spink

[pardicity3]

I am not anywhere near positive but your problem in Mozilla might be your use of an underscore (_) in your class name? Refer to this post for more:

http://www.codingforums.com/showthread.php?s=&threadid=13328

[CRASH_OVERRIDE]

Thats not the problem... underscores have always worked fine for me. It has to be a formatting problem.