Agree with everything Liam said.
lowercase_filenames_with_underscores.jpg is the way to operate, it will save you headaches later!
It's much easier using shorthand for background related CSS:
background: #ff0000 (images/filename.jpg) no-repeat scroll left top;
that will set a red background (for no color replace
#ff0000 with just the word
transparent), then applies the
filename.jpg image on top without it repeating (or use
repeat,
repeat-x or
repeat-y),
scroll means when you scroll it moves up and down on/off the screen -
fixed would make it fixed (good for a page background) - finally
left and
top and position the image to the very left and very top of the container. Liam's 50% 50% is the same as replacing
left top with
center center. It doesn't make much difference if you use the words, percents or px/em, whatever is easiest for you.
If you already knew all that apologies if it sounds patronising
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