[sinaluna]

Is there a way to prevent users from going over the pixel height limit altogether? Like, preventing them from saving the sig if it exceeds that limit.

Short Answer: not really.

Problem is that the sig height can display different in different browsers, various default text sizes, etc. The actual height is determined when the sig is rendered in the browser. Even if you could get that information back from the browser to the server, or limit it with a client-side script, it is not guaranteed to be the same height in other's browsers.

For instance, a user could shrink their default text size to the smallest setting and save their really long sig under those settings. Everyone with normal text size would have a much larger sig displayed. Hope that makes sense.