Used theme spacing

Signed-off-by: Deepak Bhardwaj <deepak.bhardwaj@outlook.com>

plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.tsx

@@ -29,7 +29,7 @@ import {
   getEntityRelations,
   useEntity,
 } from '@backstage/plugin-catalog-react';
-import { Box, makeStyles, Typography } from '@material-ui/core';
+import { Box, makeStyles, Typography, useTheme } from '@material-ui/core';
 import ZoomOutMap from '@material-ui/icons/ZoomOutMap';
 import React from 'react';
 import { useAsync } from 'react-use';
@@ -151,6 +151,7 @@ function RenderNode(props: DependencyGraphTypes.RenderNodeProps<any>) {
  */
 export function SystemDiagramCard() {
   const { entity } = useEntity();
+  const theme = useTheme();
   const currentSystemName = entity.metadata.name;
   const currentSystemNode = stringifyEntityRef(entity);
   const systemNodes = new Array<{ id: string; kind: string; name: string }>();
@@ -262,8 +263,8 @@ export function SystemDiagramCard() {
         nodeMargin={10}
         direction={DependencyGraphTypes.Direction.BOTTOM_TOP}
         renderNode={RenderNode}
-        paddingX={50}
-        paddingY={50}
+        paddingX={theme.spacing(4)}
+        paddingY={theme.spacing(4)}
       />
       <Box m={1} />
       <Typography