Nicell, center the PlayerStatusHealthBonusImage in the health element (spectatortournamentguihealth), which should be taking up the full width of the playerpanel_kv
To lower from the outside pin an element to the side of the bonus image (pin_to_sibling) so it 'covers' up the background, darkening it and making it look like an actual healthbar.
If you have the correct offset (centered bonus image) you can move 1 half of the player panel off screen for each side so you get only on side visible.
More here in Jarateking's post about the health bars.
For the ThinBorder: ClientScheme.res?