minor css fixes for old browsers

ensure no borders around image links and add fallback th solid color for old browsers that do not support gradients

dashboard/css/layout.css

@@ -10,6 +10,10 @@ h1 {
    font-size            : 25pt;
 }
 
+a img {
+   border: 0;
+}
+
 a.tip {
    text-decoration      : none;
 }
@@ -117,6 +121,7 @@ a.tip:hover span {
 .listingtable th {
    height               : 35px;
    text-align           : center;
+   background-color     : #D5EBF0;
    background-image     : -webkit-gradient(
       linear,
       left top,