You can do that without tables. Tables are for tabular information, not layout .

I think a maximum pixel size for signatures would be reasonable, and doesn't have to be subjective. Signature size could be measured with the web browser set at 'Normal' text size, which performs no additional scaling and should theoretically look the same across all modern standards-compliant browsers. Since lines of text don't always match up perfectly with pixel counts, the maximum could be approximate.