Fixed gradient background with css

html {
  height: 100%;
  /* fallback */
  background-color: #1a82f7;
  background: url(images/linear_bg_2.png);
  background-repeat: repeat-x;

  /* Safari 4-5, Chrome 1-9 */
  background: -webkit-gradient(linear, 0% 0%, 0% 100%, from(#1a82f7), to(#2F2727));

  /* Safari 5.1, Chrome 10+ */
  background: -webkit-linear-gradient(top, #2F2727, #1a82f7);

  /* Firefox 3.6+ */
  background: -moz-linear-gradient(top, #2F2727, #1a82f7);

  /* IE 10 */
  background: -ms-linear-gradient(top, #2F2727, #1a82f7);

  /* Opera 11.10+ */
  background: -o-linear-gradient(top, #2F2727, #1a82f7);
}

http://css-tricks.com/examples/CSS3Gradient/
http://css-tricks.com/css3-gradients/

Depending on what browsers you support, you may or may not want an image fallback. If not, you might want to include the filter and -ms-filter syntax instead to allow for IE 6-8. Even without this or an image it will fallback to the background-color

If you wish to do this using CSS3 gradients, try using the background-attachment property

For example, if you are applying your gradients to #background, then add this after the CSS gradient.

background-attachment: fixed;

Note: You must add background-attachment after the background properties.

Your entire code might look like this:

#background {
  background: #1e5799;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%,#1e5799), color-stop(100%,#7db9e8));
  background: -webkit-linear-gradient(top,  #1e5799 0%, #7db9e8 100%);
  background:    -moz-linear-gradient(top,  #1e5799 0%, #7db9e8 100%);
  background:     -ms-linear-gradient(top,  #1e5799 0%, #7db9e8 100%);
  background:      -o-linear-gradient(top,  #1e5799 0%, #7db9e8 100%);
  background:         linear-gradient(to bottom, #1e5799 0%, #7db9e8 100%);
  filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#1e5799', endColorstr='#7db9e8',GradientType=0 );
  background-attachment: fixed;
}