How To Small Size On Tap Tabbar Underline Using Flutter App

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  MyHomePageState createState() {
    return new MyHomePageState();
  }
}

class MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return DefaultTabController(
      length: 2,
      child: Scaffold(
        appBar: AppBar(
          backgroundColor: Colors.amber[700],
          title: Text("Small Size On Tap Tabbar"),
          bottom: TabBar(
            indicator: UnderlineTabIndicator(
              insets: EdgeInsets.fromLTRB(70.0, 0.0, 70.0, 40.0),
            ),
            tabs: <Widget>[
              Tab(text: "First Tab",),
              Tab(text: "Second Tab",),
            ],
          ),
        ),
        body: TabBarView(
          children: <Widget>[
            Center(
              child: Text("First Tab",),
            ),
            Center(
              child: Text("Second Tab"),
            ),
          ],
        ),
      ),
    );
  }
}