CSS Gradient not working on Internet Explorer 8 & 9

Question

background: #f85032;
/* Old Browsers */
background: -moz-linear-gradient(left, #f85032 0%, #f16f5c 50%, #f6290c 51%, #f02f17 71%, #e73827 100%);
/* FF3.6+ */
background: -webkit-gradient(left top, right top, color-stop(0%, #f85032), color-stop(50%, #f16f5c), color-stop(51%, #f6290c), color-stop(71%, #f02f17), color-stop(100%, #e73827));
/* Chrome,Safari4+  */
background: -webkit-linear-gradient(left, #f85032 0%, #f16f5c 50%, #f6290c 51%, #f02f17 71%, #e73827 100%);
/* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(left, #f85032 0%, #f16f5c 50%, #f6290c 51%, #f02f17 71%, #e73827 100%);
/* Opera 11.10+ */
background: -ms-linear-gradient(left, #f85032 0%, #f16f5c 50%, #f6290c 51%, #f02f17 71%, #e73827 100%);
/* IE 10+ */
background: linear-gradient(to right, #f85032 0%, #f16f5c 50%, #f6290c 51%, #f02f17 71%, #e73827 100%);
/* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#f85032', endColorstr='#e73827', GradientType=1 );
/* IE6-9 */

Answer 1

I presume you generated the code from: http://www.colorzilla.com/gradient-editor/.

I believe you missed the SVG part for IE9, below is the complete CSS needed:

background: rgb(248,80,50); /* Old browsers */
/* IE9 SVG, needs conditional override of 'filter' to 'none' */
background: url(data:image/svg+xml;base64,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);
background: -moz-linear-gradient(left,  rgba(248,80,50,1) 0%, rgba(241,111,92,1) 50%, rgba(246,41,12,1) 51%, rgba(240,47,23,1) 71%, rgba(231,56,39,1) 100%); /* FF3.6+ */
background: -webkit-gradient(linear, left top, right top, color-stop(0%,rgba(248,80,50,1)), color-stop(50%,rgba(241,111,92,1)), color-stop(51%,rgba(246,41,12,1)), color-stop(71%,rgba(240,47,23,1)), color-stop(100%,rgba(231,56,39,1))); /* Chrome,Safari4+ */
background: -webkit-linear-gradient(left,  rgba(248,80,50,1) 0%,rgba(241,111,92,1) 50%,rgba(246,41,12,1) 51%,rgba(240,47,23,1) 71%,rgba(231,56,39,1) 100%); /* Chrome10+,Safari5.1+ */
background: -o-linear-gradient(left,  rgba(248,80,50,1) 0%,rgba(241,111,92,1) 50%,rgba(246,41,12,1) 51%,rgba(240,47,23,1) 71%,rgba(231,56,39,1) 100%); /* Opera 11.10+ */
background: -ms-linear-gradient(left,  rgba(248,80,50,1) 0%,rgba(241,111,92,1) 50%,rgba(246,41,12,1) 51%,rgba(240,47,23,1) 71%,rgba(231,56,39,1) 100%); /* IE10+ */
background: linear-gradient(to right,  rgba(248,80,50,1) 0%,rgba(241,111,92,1) 50%,rgba(246,41,12,1) 51%,rgba(240,47,23,1) 71%,rgba(231,56,39,1) 100%); /* W3C */
filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#f85032', endColorstr='#e73827',GradientType=1 ); /* IE6-8 */

It states on the site about Internet Explorer Support:

Support for full multi-stop gradients with IE9 (using SVG). Add a "gradient" class to all your elements that have a gradient, and add the following override to your HTML to complete the IE9 support:

<!--[if gte IE 9]>
  <style type="text/css">
    .gradient {
       filter: none;
    }
  </style>
<![endif]-->

AFAIK Internet Explorer 8 or below doesn't support multi stop gradients.

Example: http://jsbin.com/cager/2/

Answer 2

I think your parameters are in the wrong order (but I don't have an IE 8 or 9 version to hand to test it. Try:

-ms-filter: progid:DXImageTransform.Microsoft.gradient(GradientType=1, startColorstr=#f85032, endColorstr=#e73827 );