How can I make a background transparent using css?

How开发者_运维百科 can I add a background image to an element and make it transparent?

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CSS doesn't provide a way to add translucency to just a background image.

You can use the opacity property to make the entire element (content and children included) translucent.

You can use rgba() colour values to make a plain background translucent.

If you want a translucent background image, your best bet is to edit the image itself (and save it in a format that supports translucency, such as PNG).

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Did you mean the alpha() and opacity() property?
Take a look here http://www.w3schools.com/css/css_image_transparency.asp