attempt to fix a visual problem in Dark theme

client/components/boards/boardColors.styl

@@ -15,7 +15,8 @@ setBoardColor(color)
   .is-selected .minicard
     border-left: 3px solid color
 
-  button[type=submit].primary, input[type=submit].primary
+  button[type=submit].primary, input[type=submit].primary,
+  .sidebar .sidebar-content .sidebar-btn
     background-color: darken(color, 20%)
 
   &.pop-over .pop-over-list li a:not(.disabled):hover,