diff --git a/skills/daybook-posting/SKILL.md b/skills/daybook-posting/SKILL.md
index 9edbb4d..51f4dc5 100644
--- a/skills/daybook-posting/SKILL.md
+++ b/skills/daybook-posting/SKILL.md
@@ -58,7 +58,8 @@ which is served verbatim — that's what it's for. Don't put scripts in the
 themed kinds expecting them to run; they won't.
 
 `--theme` (for `markdown`/`html_fragment` only) accepts `report` (default —
-serif, warm background), `tasks`, or `base` (minimal, no color styling).
+serif), `tasks`, or `base` (minimal sans-serif). They share the same
+off-white background and differ mainly in typography and width.
 `deck`/`html_full`/`json`/`csv` ignore `--theme` — each has its own fixed
 presentation.