Smarten up css on 20 page php form

I have a live multi page php form but it is in a table format.

I need the design and css brought up to date to make it much better looking and easier to use, particularly on tablet or smartphone.

It is necessarily from 12 up to 20 pages long with up to 10 input fields a page.

The php is fine and does not need to be touched. This is a css (and possibly js) job only.

attached is pdf print out. url of current form is on the bottom of each page