The Open-backup-center button was rendering as the raw .btn-secondary
fallback (muted grey) because the amber-tinted theme override was
scoped only to .config-actions and .console-actions — .backup-title-
actions wasn't in the selector list. Result: same shape as Back-to-Apps,
totally different colour, looked off.
Add .backup-title-actions .btn-secondary to both override blocks (the
nebula-theme rule and the default themes.css fallback) so Open backup
center now matches Back-to-Apps and the Config Reset button: solid
amber in default themes, translucent amber under nebula.
Comment also reframed — these aren't "Back to Apps"-specific anymore;
they're "step away from this page" secondary actions as a family.
Signed-off-by: librelad <librelad@digitalangels.vip>