MainWindow.xaml

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp1"
        xmlns:materialDesign="http://materialdesigninxaml.net/winfx/xaml/themes" x:Class="WpfApp1.MainWindow"
        mc:Ignorable="d"
        Title="Stars" Height="450" Width="800">

    <Grid x:Name="窗口主体" Background="White">
        <Button Margin="670,40,46,360" Content="开始" Click="Button_Click" Background="#FF2AEA00" BorderBrush="#FF2AEA00"/>
        <materialDesign:TimePicker HorizontalAlignment="Left" Margin="761,106,0,0" VerticalAlignment="Top"/>
        <TextBox HorizontalAlignment="Left" Margin="59,41,0,0" Text="TextBox" TextWrapping="Wrap" VerticalAlignment="Top" Width="556" Height="32"/>
    </Grid>

</Window>