Improve things for #5115

Grey backgrounds are fundamentally problematic when trying to display colored texts. This commit improves perceived contrast, but compromises are made to not change the style of the skins too much.

Classic coal:
- Make the background slightly less transparent and slightly darker
- Make the neutral list blue darker and the red lighter

Cartoon coal:
- Make the neutral list blue darker, the neutral red lighter, the focused blue slightly darker and the focused red darker

data/skins/cartoon-coal/stkskin.xml

@@ -269,10 +269,10 @@ Here you can configure advanced theming rules for this skin
 <color type="emphasis_text" state="focused" r="255" g="226" b="56" />
 
 <!-- Color used for red/blue items in list (e.g. player team color in networking) -->
-<color type="list_blue" state="neutral" r="0" g="0" b="180" />
-<color type="list_blue" state="focused" r="0" g="0" b="255" />
-<color type="list_red" state="neutral" r="255" g="0" b="0" />
-<color type="list_red" state="focused" r="255" g="0" b="0" />
+<color type="list_blue" state="neutral" r="0" g="0" b="90" />
+<color type="list_blue" state="focused" r="0" g="0" b="225" />
+<color type="list_red" state="neutral" r="255" g="30" b="30" />
+<color type="list_red" state="focused" r="145" g="0" b="0" />
 
 <!-- Color used to fade out background when a dialog is shown -->
 <color type="dialog_background" state="neutral" a="120" r="0" g="0" b="0" />

data/skins/classic-coal/stkskin.xml

@@ -254,10 +254,10 @@ Here you can configure advanced theming rules for this skin
 <color type="emphasis_text" state="focused" r="255" g="226" b="56" />
 
 <!-- Color used for red/blue items in list (e.g. player team color in networking) -->
-<color type="list_blue" state="neutral" r="0" g="0" b="180" />
-<color type="list_blue" state="focused" r="0" g="0" b="255" />
-<color type="list_red" state="neutral" r="255" g="0" b="0" />
-<color type="list_red" state="focused" r="255" g="0" b="0" />
+<color type="list_blue" state="neutral" r="0" g="0" b="115" />
+<color type="list_blue" state="focused" r="45" g="45" b="255" />
+<color type="list_red" state="neutral" r="255" g="30" b="30" />
+<color type="list_red" state="focused" r="255" g="30" b="30" />
 
 <!-- Color used to fade out background when a dialog is shown -->
 <color type="dialog_background" state="neutral" a="120" r="0" g="0" b="0" />