Moving to EPUB. A Basic EPUB question not specific to Sigil.
Alink and Vlink are not formatted properly to be coded in the tag. IMHO those codes belong in the stylesheet.
Tab interval .5 INCHES
for 2 reasons
1) a absolute value that won't re-flow
2) small screen users. 4 tabs and your work is in the next county
Test your work on something other
that an Apple or color screen (test on a few common, different problematic
(read here at MR and you will figure which seem to cause more