fix(support-chat): simplify legacy mobile styles

internal/web/supportchat/handler_test.go

@@ -165,15 +165,30 @@ func TestSupportChatKeepsOlderMobileWebViewsCompatible(t *testing.T) {
 		t.Fatalf("read support chat stylesheet: %v", err)
 	}
 	css := string(stylesheet)
-	for _, fallback := range []string{
-		`background: linear-gradient(145deg, #3c80fb, #4c66ea);`,
-		`background: linear-gradient(135deg, #397ffb, #5368ed);`,
-		`background: #eaf2ff;`,
-		`top: 0; right: 0; bottom: 0; left: 0; inset: 0;`,
-		`width: 100%; max-width: 360px; width: min(100%, 360px);`,
+	for _, forbidden := range []string{
+		`color-mix(`,
+		`height: 100dvh`,
+		`inset:`,
+		`width: min(`,
+		`top: max(`,
+		`backdrop-filter`,
+		`place-items`,
+		`overflow-wrap: anywhere`,
 	} {
-		if !strings.Contains(css, fallback) {
-			t.Fatalf("support chat stylesheet does not contain older mobile fallback %q", fallback)
+		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;`,
+		`color: #fff; background: #2475fc;`,
+		`background: #eaf2ff;`,
+		`top: 0; right: 0; bottom: 0; left: 0;`,
+		`width: 100%; max-width: 360px;`,
+	} {
+		if !strings.Contains(css, marker) {
+			t.Fatalf("support chat stylesheet does not contain basic mobile CSS %q", marker)
 		}
 	}
 }