fix(support-chat): simplify legacy h5 styles

internal/web/supportchat/handler_test.go

@@ -160,25 +160,37 @@ func TestSupportChatKeepsOlderMobileWebViewsCompatible(t *testing.T) {
 		}
 	}
 
+	forbiddenCSS := []string{
+		`color-mix(`,
+		`100svh`,
+		`100dvh`,
+		`inset:`,
+		`min(`,
+		`max(`,
+		`clamp(`,
+		`minmax(`,
+		`fit-content`,
+		`backdrop-filter`,
+		`place-items`,
+		`overflow-wrap: anywhere`,
+	}
+	for _, name := range []string{"assets/chat.css", "assets/demo.css"} {
+		stylesheet, readErr := assets.ReadFile(name)
+		if readErr != nil {
+			t.Fatalf("read support chat stylesheet %s: %v", name, readErr)
+		}
+		for _, forbidden := range forbiddenCSS {
+			if strings.Contains(string(stylesheet), forbidden) {
+				t.Fatalf("support chat stylesheet %s must not require newer mobile CSS %q", name, forbidden)
+			}
+		}
+	}
+
 	stylesheet, err := assets.ReadFile("assets/chat.css")
 	if err != nil {
 		t.Fatalf("read support chat stylesheet: %v", err)
 	}
 	css := string(stylesheet)
-	for _, forbidden := range []string{
-		`color-mix(`,
-		`height: 100dvh`,
-		`inset:`,
-		`width: min(`,
-		`top: max(`,
-		`backdrop-filter`,
-		`place-items`,
-		`overflow-wrap: anywhere`,
-	} {
-		if strings.Contains(css, forbidden) {
-			t.Fatalf("support chat stylesheet must not require newer mobile CSS %q", forbidden)
-		}
-	}
 	for _, marker := range []string{
 		`.message-row.mine .message-bubble { border-color: #2475fc;`,
 		`.send-button { width: 40px; height: 40px;`,