AlarmWindow.xaml

<Window
    x:Class="AlarmApp.AlarmWindow"
    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:local="clr-namespace:AlarmApp"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    Title="Alarm!!!"
    Width="300"
    Height="170"
    mc:Ignorable="d">
    <Window.Style>
        <Style BasedOn="{StaticResource {x:Type Window}}" TargetType="{x:Type Window}" />
    </Window.Style>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="20" />
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="20" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="30" />
            <RowDefinition Height="*" />
            <RowDefinition Height="30" />
        </Grid.RowDefinitions>
        <TextBlock
            Grid.Column="1"
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            Text="Your alarm is ready!!!" />
    </Grid>
</Window>