Basic fallbacks for IE

media/css/fallback.css

@@ -1,3 +1,54 @@
-.no-opacity .home #spark-content, .no-opacity .home #firefox-content {
+.no-opacity .home #spark-content, 
+.no-opacity .home #firefox-content,
+.no-opacity .spark #firefox-content,
+.no-opacity .spark #home,
+.no-opacity .firefox #spark-content,
+.no-opacity .firefox #home,
+.no-opacity .spark-1 #spark-2,
+.no-opacity .spark-1 #spark-3,
+.no-opacity .spark-2 #spark-1,
+.no-opacity .spark-2 #spark-3,
+.no-opacity .spark-3 #spark-1,
+.no-opacity .spark-3 #spark-2,
+.no-opacity .layer-1 #layer-2,
+.no-opacity .layer-1 #layer-3,
+.no-opacity .layer-1 #layer-4,
+.no-opacity .layer-2 #layer-1,
+.no-opacity .layer-2 #layer-3,
+.no-opacity .layer-2 #layer-4,
+.no-opacity .layer-3 #layer-1,
+.no-opacity .layer-3 #layer-2,
+.no-opacity .layer-3 #layer-4,
+.no-opacity .layer-4 #layer-1,
+.no-opacity .layer-4 #layer-2,
+.no-opacity .layer-4 #layer-3 {
     visibility:hidden;
 }
+
+.no-opacity .tooltip {
+    visibility:hidden;
+}
+
+.no-cssgradients #spark-button {
+    background:url('../img/fallbacks/yellow-bg.png') repeat-x 0 0;
+}
+
+.no-cssgradients #firefox-button {
+    background:url('../img/fallbacks/blue-bg.png') repeat-x 0 0;
+}
+
+.no-cssgradients #ff-download {
+    background:url('../img/fallbacks/green-bg.png') repeat-x 0 0;
+}
+
+.no-boxshadow #spark-button {
+    border-bottom:3px solid #ad9d35;
+}
+
+.no-boxshadow #firefox-button {
+    border-bottom:3px solid #346b88;
+}
+
+.no-boxshadow #ff-download {
+    border-bottom:3px solid #779c00;
+}

media/css/firefox-4.css

@@ -58,14 +58,20 @@
 }
 
 #layer-4 .block-3 .icon {
-    height:25px;
+    height:26px;
     width:25px;
     margin-right:10px;
-    background:#444;
     float:left;
     margin-top:-5px;
 }
 
+#layer-4 .block-3 ul:nth-child(1) li:nth-child(1) .icon {background:url('../img/sprites-firefox.png') no-repeat 0 -300px;}
+#layer-4 .block-3 ul:nth-child(1) li:nth-child(2) .icon {background:url('../img/sprites-firefox.png') no-repeat -25px -300px;}
+#layer-4 .block-3 ul:nth-child(1) li:nth-child(3) .icon {background:url('../img/sprites-firefox.png') no-repeat -50px -300px;}
+#layer-4 .block-3 ul:nth-child(2) li:nth-child(1) .icon {background:url('../img/sprites-firefox.png') no-repeat -75px -300px;}
+#layer-4 .block-3 ul:nth-child(2) li:nth-child(2) .icon {background:url('../img/sprites-firefox.png') no-repeat -100px -300px;}
+#layer-4 .block-3 ul:nth-child(2) li:nth-child(3) .icon {background:url('../img/sprites-firefox.png') no-repeat -125px -300px;}
+
 #layer-4 .block-4, #layer-4 .block-5 {
     margin-top:20px;
 }