My first EPUB! Need advice on best practices

[fluoresce]

I've found a way to ensure that ADE doesn't scale the table images down too much. Quite simply, I am preventing it from splitting my ebook's content into columns using this bit of code:

body {
oeb-column-number: 1;
}

When ADE creates narrow columns, the table images are scaled down a lot, which makes them look unreadable. However, when I force a single wide column, the images aren't scaled down, so they look fine.

The problem now is that I get a CSS error when I try to validate on W3. It says that oeb-column-number doesn't exist!

Is this code safe to use?

[fluoresce]

I've decided not to use

oeb-column-number: 1;

It's not the right fix. I have to fix the images properly.