Red box/color for @ when severely wounded

[PowerWyrm]

Sometimes I lose characters for not being paranoid about HPs, because there's no warning when you are low on health (except watching the HP bar after every turn). The "LOW HEALTH" indicator seems bugged or ill-adapted (sometimes it appears constantly when you have 800 HPs left at high level, sometimes it doesn't appear at all when you have 1 HP left...).
Perhaps an additional red warning on the @ would be helpful...

[Final Master]

Or how about letting the player set the %hp amount for the warning to pop?