ONOS-4359: continued work on theming UI
- cleaned up application confirmation dialog.

Change-Id: I498ef3897f828611ed8677873bcfcbcc3b09e1cc
(cherry picked from commit cf4b9a3)
diff --git a/web/gui/src/main/webapp/app/fw/layer/dialog-theme.css b/web/gui/src/main/webapp/app/fw/layer/dialog-theme.css
index bda182e..213b7fa 100644
--- a/web/gui/src/main/webapp/app/fw/layer/dialog-theme.css
+++ b/web/gui/src/main/webapp/app/fw/layer/dialog-theme.css
@@ -18,15 +18,12 @@
  ONOS GUI -- Dialog Service (theme) -- CSS file
  */
 
-.light .dialog h2 {
-    color: black;
+.light .dialog .dialog-button {
+    background-color: #518ecc;
+    color: white;
 }
-.dark .dialog h2 {
-    color: #ddd;
-}
-
-.dialog .dialog-button {
-    /* color works for both light and dark themes */
-    background-color: #c55;
+.dark .dialog .dialog-button {
+    /* TODO: dark theme */
+    background-color: #518ecc;
     color: white;
 }