Website linking is definitely allowed here, even encouraged, since it gives me a chance to see your work, and better answer questions.
That said, the best and easiest way to do partial transparency in the browser is with a partially transparent image, rather than doing CSS tricks (which are still pretty wonky).
If you want, use
this image as your background image (it's a partially transparent grey image we use in another template).
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It's all in the reflexes.