diff --git a/layouts/partials/highlightgroup.html b/layouts/partials/highlightgroup.html
index 6208044..0957d8d 100644
--- a/layouts/partials/highlightgroup.html
+++ b/layouts/partials/highlightgroup.html
@@ -1 +1,9 @@
-{{ partial "group.html" (dict "url" .url "path" .path "comment" .comment "content" (highlight .code .language .opts)) }}
+{{- if eq .language "Agda" -}}
+{{- page.Scratch.Set "highlightGroupAttrs" (printf "data-agda-block") -}}
+{{- if (or .firstLine .lastLine) -}}
+{{- page.Scratch.Add "highlightGroupAttrs" (printf " data-agda-first-line=\"%v\" data-agda-last-line=\"%v\"" .firstLine .lastLine) -}}
+{{- end -}}
+{{- else -}}
+{{- page.Scratch.Set "highlightGroupAttrs" nil -}}
+{{- end -}}
+{{ partial "group.html" (dict "url" .url "path" .path "comment" .comment "content" (highlight .code .language .opts) "attrs" (page.Scratch.Get "highlightGroupAttrs")) }}