I'm kind of getting to grips with CSS but what I need help with is this:- I've got a table, with a background image. the table has a number of cells.
I would like to get each cell transparent(maybe 50%) and on mouseover become transparent - so you see the image.
My problem is the syntax. any pointers.

This is the code I'm using

style="background-color: gray;(50%);"
onmouseover = "this.style.backgroundColor='transparent';"
onmouseout = "this.style.backgroundColor='gray';"

Now if I could get the gray color to be opaque or use an image[blurred version of the background image]

thanks in advance