diff --git a/web/src/lib/components/ui/ButtonGroup.svelte b/web/src/lib/components/ui/ButtonGroup.svelte
index 6b7a19791..16804216a 100644
--- a/web/src/lib/components/ui/ButtonGroup.svelte
+++ b/web/src/lib/components/ui/ButtonGroup.svelte
@@ -13,6 +13,12 @@
 					"[&>*:first-child]:-ml-px [&>*:last-child]:-mr-px",
 					"[&>*:not(:first-child)]:-ml-px [&>*:not(:first-child)]:[--btn-radius-l:0px]",
 					"[&>*:not(:last-child)]:[--btn-radius-r:0px]",
+					// a Dropdown keeps its trigger one level down, and the radius vars only
+					// inherit that far — Button re-declares them on itself, so the wrapper's
+					// value loses. reach the nested trigger directly.
+					"[&>*>button]:border-y-0",
+					"[&>*:not(:first-child)>button]:[--btn-radius-l:0px]",
+					"[&>*:not(:last-child)>button]:[--btn-radius-r:0px]",
 					// children overlap by 1px so adjacent borders collapse into a single seam, which
 					// also means a child's fill paints into its neighbour's border column. ghost
 					// segments have a transparent border and nothing to repaint there, so every