diff --git a/packages/grafana-ui/src/components/uPlot/plugins/TooltipPlugin.tsx b/packages/grafana-ui/src/components/uPlot/plugins/TooltipPlugin.tsx
index a9ee42efb33..0bcf7ae53ad 100644
--- a/packages/grafana-ui/src/components/uPlot/plugins/TooltipPlugin.tsx
+++ b/packages/grafana-ui/src/components/uPlot/plugins/TooltipPlugin.tsx
@@ -327,7 +327,7 @@ export function positionTooltip(u: uPlot, bbox: DOMRect) {
 }
 
 const getStyles = (theme: GrafanaTheme2) => ({
-  tooltipWrapper: css`
-    z-index: ${theme.zIndex.portal + 1} !important;
-  `,
+  tooltipWrapper: css({
+    'z-index': theme.zIndex.portal + 1 + ' !important',
+  }),
 });