Provided the design spec padding value to the cells.

Author: ashok-kuvaraja

lib/main.dart

@@ -46,22 +46,22 @@ 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',
               width: 110,
               label: Container(
-                  padding: EdgeInsets.all(8.0),
+                  padding: const EdgeInsets.symmetric(horizontal: 16.0),
                   alignment: Alignment.center,
                   child: Text(
                     'Designation',
@@ -70,7 +70,7 @@ 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'))),
         ],
@@ -163,7 +163,7 @@ 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());