How do I change the background opacity of a block?

How would I go about changing the background opacity of a content block? This is the current code I have in the CSS Editor:

#block-4e5265faf96ce435b6ce {
 border-style: double white 10px;
 background-color: black; opacity: .3;
 padding-top: 20px
}

Use RGBA to set the color, it supports alpha transparency as the 4th parameter:

block-4e5265faf96ce435b6ce {
 border-style: double;
 border-color: white;
 border-width: 10px;
 padding-top: 20px;
 background-color: #afafaf; /* fallback for old browsers */
 background-color: rgba(0, 0, 0, .3);
}

it worked. thank you!

Don't forget to mark answers as accepted so others can find them and more answers aren't offered etc.

If you need to change opacity of color of background, just use RGBA color as described here: CSS3: semi-transparent background color using RGBA

try this background on div

background: rgba(255,255,255,.5);

Full source : Transparent Div

Naimer

Make sure to grab your own block ID for this. You can remove the border style and stuff too if you don't want that.