CSS中的背景图像不透明度（在Dreamweaver中工作）

Question

Working in Dreamweaver, I'm trying to get a background image that is the same on every page. I want it to be set and fill the whole page, have content scroll not the picture, and I need the picture to be a bit transparent, so the text will be easier to read. I have NO idea how to do opacity other than that this is what I have in my Style.css class.

body {
    overflow-x: hidden;
    width: 100%;
    background-image:
         url(/CuzbZDV%5B1%5D.jpg);
    background-repeat: no-repeat;
    background-position: top center;
    background-attachment: fixed;
}

Answer 1

Try with that:

body:before {
  position: fixed;
  z-index: -1;
  content: " ";
  top: 0; left: 0; right: 0; bottom: 0;
  background: url() no-repeat center center fixed;
  background-size: cover;
  opacity: .5;
  filter: alpha(opacity=50); /* IE8, I believe... */
}