OO-1581 fix IE11 bug in login bg carousel, add IE9 gradient to login bg

src/main/webapp/static/themes/light/modules/_dmz.scss

@@ -20,13 +20,36 @@ body.o_dmz {
 			$o-login-bg-gradient-to : top;
 		}
 		
-		/* bg without gradient, as fallback for ie < 10 */
+		/* Full screen background image */
 		background: url('#{$o-login-form-bg-img}');
-
-		background: linear-gradient(to $o-login-bg-gradient-to, $o-login-form-bg-gradient-steps...), url('#{$o-login-form-bg-img}');
-		background-size: cover, cover;
-		background-position: $o-login-form-bg-position-left $o-login-form-bg-position-top, $o-login-form-bg-position-left $o-login-form-bg-position-top;
+		background-size: cover;
+		background-position: $o-login-form-bg-position-left $o-login-form-bg-position-top;
 		background-repeat: no-repeat;
+		
+		/* overlay gradient to make login form better readable */
+		&:after {
+			content: " ";
+			position: absolute;
+			top: 0;
+			left: 0;
+			width: 100%;
+			height: 100%;
+			background: linear-gradient(to $o-login-bg-gradient-to, $o-login-form-bg-gradient-steps...);
+			background-size: cover;
+			background-position: $o-login-form-bg-position-left $o-login-form-bg-position-top;
+			background-repeat: no-repeat;
+		}
+						
+		/* IE 9 fallback for gradient */
+		@if $o-login-form-align == left {
+			filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffffff', endColorstr='#00ffffff',GradientType=1 );
+		}
+		@else if $o-login-form-align == right {
+			filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#00ffffff', endColorstr='#ffffff',GradientType=1 );
+		} 
+		@else if $o-login-form-align == center {
+			filter: progid:DXImageTransform.Microsoft.gradient( startColorstr='#ffffff', endColorstr='#00ffffff',GradientType=0 );
+		} 
 	}
 
 	#o_main_wrapper, #o_main_wrapper #o_main_container {