AngularJS ng-自封闭输入标签的有效问题？

Question

这是我在遵循官方文档中提供的角度js文档时编写的代码。

<div ng-controller="ExampleController">
    <form novalidate class="css-form">
        Name: <input type="text" ng-model="user.name" required><br>
        Email: <input type="email" ng-model="user.email" required><br>
        Gender: <input type="radio" ng-model="user.gender" value="male">Male
        <input type="radio" ng-model="user.gender" value="Female">Female <br>
        <input type="button" ng-click="reset()" value="Reset">
        <input type="submit" ng-click="update(user)" value="Save">
    </form>
    <pre>user = {{ user | json }}</pre>
    <pre>master = {{ master | json }}</pre>
</div>

这不起作用（更改模糊输入的颜色）。如何运作，

<div ng-controller="ExampleController">
    <form novalidate class="css-form">
        Name: <input type="text" ng-model="user.name" required /><br>
        Email: <input type="email" ng-model="user.email" required /><br>
        Gender: <input type="radio" ng-model="user.gender" value="male">Male
        <input type="radio" ng-model="user.gender" value="Female">Female <br>
        <input type="button" ng-click="reset()" value="Reset">
        <input type="submit" ng-click="update(user)" value="Save">
    </form>
    <pre>user = {{ user | json }}</pre>
    <pre>master = {{ master | json }}</pre>
</div>

我不明白原因。有人知道这个的原因吗？