Provided the design spec padding value to the cells.

Author: ashok-kuvaraja

lib/main.dart

@@ -46,21 +46,21 @@ class _MyHomePageState extends State<MyHomePage> {
             GridTextColumn(
                 columnName: 'id',
                 label: Container(
-                    padding: EdgeInsets.all(16.0),
+                    padding: const EdgeInsets.symmetric(horizontal: 16.0),
                     alignment: Alignment.center,
                     child: Text(
                       'ID',
                     ))),
             GridTextColumn(
                 columnName: 'name',
                 label: Container(
-                    padding: EdgeInsets.all(8.0),
+                    padding: const EdgeInsets.symmetric(horizontal: 16.0),
                     alignment: Alignment.center,
                     child: Text('Name'))),
             GridTextColumn(
                 columnName: 'designation',
                 label: Container(
-                    padding: EdgeInsets.all(8.0),
+                    padding: const EdgeInsets.symmetric(horizontal: 16.0),
                     alignment: Alignment.center,
                     child: Text(
                       'Designation',
@@ -69,7 +69,7 @@ class _MyHomePageState extends State<MyHomePage> {
             GridTextColumn(
                 columnName: 'salary',
                 label: Container(
-                    padding: EdgeInsets.all(8.0),
+                    padding: const EdgeInsets.symmetric(horizontal: 16.0),
                     alignment: Alignment.center,
                     child: Text('Salary'))),
           ],
@@ -133,7 +133,7 @@ class EmployeeDataSource extends DataGridSource {
         cells: row.getCells().map<Widget>((e) {
       return Container(
         alignment: Alignment.center,
-        padding: EdgeInsets.all(8.0),
+        padding: const EdgeInsets.symmetric(horizontal: 16.0),
         child: Text(e.value.toString()),
       );
     }).toList());