Formatting table colour is messing up Javascript

I've setup a table to calculate cells but i'm having trouble with formatting the colors within the table. When I make certain changes, the table calculations stop working. I've uploaded some examples:

www.fluxcreative.co.uk/first.html

In this example, the lines numbered 2-6 total at the bottom when checked as they should do.

but after changing the code for line 1 (so the row changes color when checked), the line has stopped adding to the totals

Line 1 is almost formatted correctly but you'll notice it is white when the page loads, turquoise when checked then reverts to light purple. The light purple is the color it should be before the box is checked but because the line colors alternate, I don't wanna change the BG color of the whole table. So i've added some code to set odd numbered rows to dark and even numbers to light, so line 1 now works how it should do color-wise (see below).

www.fluxcreative.co.uk/second.html

But now, all lines have stopped adding up!!! I've put this together from snippets on google but I don't really understand CSS well enough to work this out. Color and functionality are both very important for this site but I can't get them working together. Can someone please tell me where i'm going wrong? Thanks guys, Dren