Hey @GraphiteGhost and @Robb M. the issue that GraphiteGhost is reporting is due to the usage of the size tag and breaking the What You See Is What You Get Editor.

Robb, does that signature appear correctly in the Edit Signature editor with the markup correctly displayed on your device? iOS? It's possible it could be browser or Windows specific but it looks to me to be universal.

As you can see in the editor, there's two lines missing and it's due to the size tags. Both of those lines have a specified size tag and so the editor is not displaying it correctly during edits.