Update jira-dark-gray.user.css (#21)

fixes #18

Author: aalvarado

jira-dark-gray.user.css

@@ -1,7 +1,7 @@
 /* ==UserStyle==
 @name         Jira Dark Gray
 @namespace    github.com/aalvarado
-@version      1.7.0
+@version      1.8.0
 @license      BSD
 @preprocessor default
 
@@ -113,6 +113,11 @@ regexp(".*.atlassian.net/secure.*") {
     .adg3 .ghx-column .ghx-parent-group {
         background-color: #555;
     }
+    
+    /* subtask parent task label */
+    .adg3 .ghx-key {
+        color: #ddd;
+    }
 
     /***
      * Left-hand Nav
@@ -639,8 +644,6 @@ regexp(".*.atlassian.net/secure.*") {
         margin-top: 5px;
     }
 
-
-    
     .css-b6ncbb:hover,
     button:hover{
         background-color: #555 !important;