Scrap the over-engineered version. Start from irssi's default theme
(already dark-safe) and apply rainbow only where it actually earns
its keep:
- line_start: the leading '-!-' on non-message lines gets a full
R-Y-G-C-B-M dash sequence instead of blue-blue.
- sb_act_msg: drop the %W (white) on statusbar activity — on a dark
terminal this was the one stark-white glyph. Re-colour the whole
activity band as a rainbow escalation: %G (quiet) -> %Y (chatter)
-> %R (hilight), so urgency tracks the colour.
- sb_act_sep: comma separator drops to %K (dark grey) so the rainbow
entries stand apart.
Everything else stays untouched from default.theme. No invented
24-bit escapes, no format overrides.