Limitations to external loaded css?

are there some limitations to the css that can be used in an externally loaded style sheet and externally loaded textfile? I’m using the kirupa tutorials: http://www.kirupa.com/developer/mx2004/cssfile.htm and I followed the first one first.

This is my style sheet:
.contenthead {
font-family: Helvetica, Arial, sans-serif;
font-size: 18px;
font-weight: bold;
color: 663300;
margin-left: 10px;
margin-top: 25px;
width: auto;
}
.contentmain {
font-family: Helvetica, Arial, sans-serif;
font-size: 10px;
color: #663300;
margin-left: 10px;
width: 415px;
text-align: justify;
}
.contentminihead {

font-family: Helvetica, Arial, sans-serif;
font-weight:bold;
font-size: 11px;
color: #663300;
margin-left: 10px;
width: 415px;
text-align: justify;

}

The “width” property doesnt seem to make a difference, or text-align. font-family and size and color seem to render ok, though.

Here’s the page itself:
http://idiaonline.com/websites/vjc/academy.html

Using MX2004.

Anyone know what to do?