CSS3 Transparency + Gradient

New syntax has been supported for a while by all modern browsers (starting from Chrome 26, Opera 12.1, IE 10 and Firefox 16): http://caniuse.com/#feat=css-gradients

background: linear-gradient(to bottom, rgba(0, 0, 0, 1), rgba(0, 0, 0, 0));

This renders a gradient, starting from solid black at the top, to fully transparent at the bottom.

Documentation on MDN.

This is some really cool stuff! I needed pretty much the same, but with horizontal gradient from white to transparent. And it is working just fine! Here ist my code:

.gradient{
        /* webkit example */
        background-image: -webkit-gradient(
          linear, right top, left top, from(rgba(255, 255, 255, 1.0)),
          to(rgba(255, 255, 255, 0))
        );

        /* mozilla example - FF3.6+ */
        background-image: -moz-linear-gradient(
          right center,
          rgba(255, 255, 255, 1.0) 20%, rgba(255, 255, 255, 0) 95%
        );

        /* IE 5.5 - 7 */
        filter: progid:DXImageTransform.Microsoft.gradient(
          gradientType=1, startColor=0, endColorStr=#FFFFFF
        );

        /* IE8 uses -ms-filter for whatever reason... */
        -ms-filter: progid:DXImageTransform.Microsoft.gradient(
          gradientType=1, startColor=0, endColoStr=#FFFFFF
        );
    }

Yes. You can use rgba in both webkit and moz gradient declarations:

/* webkit example */
background-image: -webkit-gradient(
  linear, left top, left bottom, from(rgba(50,50,50,0.8)),
  to(rgba(80,80,80,0.2)), color-stop(.5,#333333)
);

(src)

/* mozilla example - FF3.6+ */
background-image: -moz-linear-gradient(
  rgba(255, 255, 255, 0.7) 0%, rgba(255, 255, 255, 0) 95%
);

(src)

Apparently you can even do this in IE, using an odd "extended hex" syntax. The first pair (in the example 55) refers to the level of opacity:

/* approximately a 33% opacity on blue */
filter: progid:DXImageTransform.Microsoft.gradient(
  startColorstr=#550000FF, endColorstr=#550000FF
);

/* IE8 uses -ms-filter for whatever reason... */
-ms-filter: progid:DXImageTransform.Microsoft.gradient(
  startColorstr=#550000FF, endColorstr=#550000FF
);

(src)