Use css gradient over background image

I've been trying to use a linear gradient on top of my background image in order to get a fading effect on the bottom of my background from black to transparent but can't seem to be able to make it show.

I've read other cases here and examples but none of them are working for me. I can only see the gradient or the image but not both of them. Here's the link

Just click on the first logo, ignore that effect, what I'm trying is in the body in the whole site after that.

This is my css code:

body {
  background: url('http://www.skrenta.com/images/stackoverflow.jpg') no-repeat, -webkit-gradient(linear, left top, left bottom, from(rgba(0, 0, 0, 0.1)), to(rgba(0, 0, 0, 1)));
}

Ok, I solved it by adding the url for the background image at the end of the line.

Here's my working code:

.css {
  background: -moz-linear-gradient(top, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 59%, rgba(0, 0, 0, 0.65) 100%), url('https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png?v=c78bd457575a') no-repeat;
  background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, rgba(0, 0, 0, 0)), color-stop(59%, rgba(0, 0, 0, 0)), color-stop(100%, rgba(0, 0, 0, 0.65))), url('https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png?v=c78bd457575a') no-repeat;
  background: -webkit-linear-gradient(top, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 59%, rgba(0, 0, 0, 0.65) 100%), url('https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png?v=c78bd457575a') no-repeat;
  background: -o-linear-gradient(top, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 59%, rgba(0, 0, 0, 0.65) 100%), url('https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png?v=c78bd457575a') no-repeat;
  background: -ms-linear-gradient(top, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 59%, rgba(0, 0, 0, 0.65) 100%), url('https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png?v=c78bd457575a') no-repeat;
  background: linear-gradient(to bottom, rgba(0, 0, 0, 0) 0%, rgba(0, 0, 0, 0) 59%, rgba(0, 0, 0, 0.65) 100%), url('https://cdn.sstatic.net/Sites/stackoverflow/company/img/logos/so/so-icon.png?v=c78bd457575a') no-repeat;
  height: 200px;

}

<div class="css"></div>

body {
    margin: 0;
    padding: 0;
    background: url('img/background.jpg') repeat;
}

body:before {
    content: " ";
    width: 100%;
    height: 100%;
    position: absolute;
    z-index: -1;
    top: 0;
    left: 0;
    background: -webkit-radial-gradient(top center, ellipse cover, rgba(255,255,255,0.2) 0%,rgba(0,0,0,0.5) 100%);
}

PLEASE NOTE: This only using webkit so it will only work in webkit browsers.

try :

-moz-linear-gradient = (Firefox)
-ms-linear-gradient = (IE)
-o-linear-gradient = (Opera)
-webkit-linear-gradient = (Chrome & safari)

#multiple-background{
	box-sizing: border-box;
	width: 123px;
	height: 30px;
	font-size: 12pt;
	border-radius: 7px;		
	background: url("https://cdn0.iconfinder.com/data/icons/woocons1/Checkbox%20Full.png"), linear-gradient(to bottom, #4ac425, #4ac425);
	background-repeat: no-repeat, repeat;
	background-position: 5px center, 0px 0px;
    background-size: 18px 18px, 100% 100%;
	color: white;	
	border: 1px solid #e4f6df;
	box-shadow: .25px .25px .5px .5px black;
	padding: 3px 10px 0px 5px;
	text-align: right;
	}

<div id="multiple-background"> Completed </div>

The accepted answer works well. Just for completeness (and since I like it's shortness), I wanted to share how to to it with compass (SCSS/SASS):

body{
  $colorStart: rgba(0,0,0,0);
  $colorEnd: rgba(0,0,0,0.8);
  @include background-image(linear-gradient(to bottom, $colorStart, $colorEnd), url("bg.jpg"));
}