I think plugin is the only way unless I make manual offsets for each resolution (like I did for 2 already). Which is super hacky/tacky/wacky. I want to avoid hours of pixel peeping and also confusion of overwriting files for the player.
Right now even if I make the buttons be sized "center" horizontally, there is no way to offset them. So I can only have 1 button be in absolute center, when I need to do 2.
Shifting from pixel values to percentages is the way to fix this.
There has to be a fairly straightforward method of hooking these GUI elements and having them respond to commands like "10% from left side of $fullscreen_res" etc.
Or, you know, just add CSS3 support.
Edit: But yes please put together HQ base\textures add-on pack that someone can just drop-in.
Edit2: Added your mars sky to v1.1