Add doctype html (i.e. html5) to the card template.
Rename the card templates.
Set the charset to utf-8 on the card.
Don’t do horizontal align.
Let the webkit worry about resizing images.
Vertical centering without tables as an option. Thanks to @hssm
Use inner div with margins and make margins smaller.
Checkbox to center vertically (old style) or not (everything at top, like desktop).
Semi-automatically remove a few trailing spaces.
Separate the chess and legacy ruby css into extra files.
Add CSS classes to identify android devices