Update the Litmus theme

Author: xyproto

Diff for: v2/themes.go

@@ -419,7 +419,7 @@ func NewLitmusTheme() Theme {
 		HTMLColor:                   vt100.Black,
 		CommentColor:                vt100.DarkGray,
 		BoldColor:                   vt100.Red,
-		ItalicsColor:                vt100.Gray,
+		ItalicsColor:                vt100.DarkGray,
 		StrikeColor:                 vt100.DarkGray,
 		TableColor:                  vt100.Black,
 		CheckboxColor:               vt100.Black,
@@ -442,7 +442,7 @@ func NewLitmusTheme() Theme {
 		DebugOutputBackground:       vt100.BackgroundGray,
 		DebugInstructionsForeground: vt100.Red,
 		DebugInstructionsBackground: vt100.BackgroundMagenta,
-		BoxUpperEdge:                vt100.Gray,
+		BoxUpperEdge:                vt100.DarkGray,
 		JumpToLetterColor:           vt100.LightRed,
 		NanoHelpForeground:          vt100.Black,
 		NanoHelpBackground:          vt100.BackgroundGray,