UWP 圆角TEXTBOX和PASSWORD框

最近在做一个UWP项目,登录的用户和密码框需要圆角的,由于UWP的TextBlock 和PasswordBox是没有CornerRadius属性的,于是我就使用了一个Border嵌套在最外层,设置其他CornerRadius="20"

<!--账号-->
                        <Border Background="#FFFFFF" CornerRadius="20">
                            <RelativePanel Margin="10,0,0,0" Padding="5">
                                <TextBlock  x:Name="tbNumber" Text="账号：" RelativePanel.AlignVerticalCenterWithPanel="True" />
                                <TextBox x:Name="txtUserName" FontSize="16"  RelativePanel.RightOf="tbNumber" PlaceholderText="请输入GW号/手机号"
                                         RelativePanel.AlignRightWithPanel="True" 
                                         RelativePanel.AlignHorizontalCenterWithPanel="True"
                                         RelativePanel.AlignVerticalCenterWithPanel="True"
                                         Margin="0,5,0,0" 
                                         BorderThickness="0"
                                         InputScope="NameOrPhoneNumber"/>
                            </RelativePanel>
                        </Border>
                        <!--密码-->
                        <Border Background="#FFFFFF" CornerRadius="20" Margin="0,20,0,0">
                            <RelativePanel Margin="10,0,0,0" Padding="5">
                                <TextBlock  x:Name="tbPwd" Text="密码：" RelativePanel.AlignVerticalCenterWithPanel="True" />
                                <PasswordBox x:Name="txtPwd" RelativePanel.RightOf="tbPwd" PlaceholderText="请输入密码"
                                             RelativePanel.AlignRightWithPanel="True" IsEnabled="True"
                                             BorderThickness="0" 
                                             RelativePanel.AlignHorizontalCenterWithPanel="True"
                                             RelativePanel.AlignVerticalCenterWithPanel="True"
                                             Margin="0,5,0,0"/>
                            </RelativePanel>
                        </Border>