More IE fixes. Using important to override blocky related CSS.

theme/style.less

@@ -45,8 +45,8 @@
 *******************************/
 
 .blocklyTreeRow {
-    border-bottom: 1px solid #ecf0f1;
-    margin-bottom: 0px;
+    border-bottom: 1px solid #ecf0f1 !important;
+    margin-bottom: 0px !important;
 }
 
 /* Blockly toolbox font size same as the page font */
@@ -60,7 +60,7 @@
 }
 
 .blocklyFlyoutBackground {
-    fill: #525A67;
+    fill: #525A67 !important;
 }
 
 /* Remove shadow around blockly blocks */
@@ -84,6 +84,10 @@
     background: #ecf0f1;
 }
 
+.monacoFlyout {
+    background: rgba(82, 90, 103, 0.8);
+}
+
 
 /* Mobile */
 @media only screen and (max-width: @largestMobileScreen) {