Another item that needs to be addressed is wrapping in cells. You might imagine a table like this:

This is column 1 and 2 and 3 and 4
Here's data and more data and even more data

It's a small table, I gave it a width of only 200px; so certainly it starts wrapping things.
Since I want the table to have that small width, it has to wrap things, sure, but look at the headers of the columns 2 to 4. That doesn't look nice, huh? Okay, let's make those header-cells stop wrapping the text (but the first one should still wrap or our table will simply become big again.
I will add this code white-space:nowrap to a class and put that class on those 3 column headers. The opposite would simply be white-space:normal

table-layout:auto;
table-layout:fixed;