信息输入验证成功后，表单下方为什么会出现空白部分，如何去掉？
源代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<link rel="stylesheet" href="./libs/bootstrap.min.css">
<link rel="stylesheet" href="./libs/font-awesome.min.css">
<style>
.wrapper{
width: 240px;
margin: 20px auto;
}
.error{
color: #a30;
}
p.success{
color: #5bc648;
}
.input-check{
position: relative;
top: -30px;
left: 215px;
}
input.error{
border: 1px solid #a30;
}
</style>
<title>Document</title>
</head>
<body ng-app="myApp" ng-controller="SignUpController">
<div class="wrapper">
<h2>新用户注册</h2>
<form name="signUpForm" ng-submit="submitForm()" action="">
<div class="form-group" ng-class="{ 'success': signUpForm.username.$valid">
<label for="">用户名：</label>
<input type="text"
name="username"
class="form-control"
ng-model="userdata.username"
ng-minlength="4"
ng-maxlength="32"
required><!--用户名必须存在-->
<p class="fa fa-check input-check success" ng-if="signUpForm.username.$valid"></p>
<p class="error" ng-if="signUpForm.username.$error.required && signUpForm.username.$touched">用户名不能为空！</p>
<p class="error" ng-if="(signUpForm.username.$error.minlength ||
signUpForm.username.$error.maxlength) && signUpForm.username.$touched">用户名的长度应在4-32位之间！</p>
</div>
<div class="form-group" ng-class="{'success': signUpForm.password.$valid}">
<label for="">密码：</label>
<input type="password"
name="password"
class="form-control"
ng-model="userdata.password"
ng-minlength="8"
ng-maxlength="32"
required>
<p class="fa fa-check input-check success" ng-if="signUpForm.password.$valid"></p>
<p class="error" ng-if="signUpForm.password.$error.required && signUpForm.password.$touched">密码不能为空！</p>
<p class="error" ng-if="(signUpForm.password.$error.minlength ||
signUpForm.password.$error.maxlength) && signUpForm.password.$touched">密码长度应在8-32之间</p>
</div>
<div class="form-group">
<label for="">确认密码：</label>
<input type="password"
name="password2"
class="form-control"
ng-model="userdata.password2"
compare="userdata.password"
required>
<p class="fa fa-check input-check success" ng-if="signUpForm.password2.$valid"></p>
<p class="error" ng-if="signUpForm.password2.$error.compare && signUpForm.password2.$touched">两次密码输入不一致！</p>
</div>
<div class="form-group">
<button class="btn btn-primary">提交</button>
</div>
</form>
</div>
<script src="./libs/angular.min.js"></script>
<script src="./js/main.js"></script>
</body>
</html>
