App.xaml

<Application x:Class="CourseSelectionSystem.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:CourseSelectionSystem">

    <Application.Resources>
        <Style x:Key="MenuListBoxItemStyle" TargetType="ListBoxItem">
            <Setter Property="Background" Value="Transparent"/>
            <Setter Property="BorderThickness" Value="0"/>
            <Setter Property="Margin" Value="0,2"/>
            <Setter Property="IsSelected" Value="False"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ListBoxItem">
                        <Border Name="Border" 
                        Padding="0" 
                        Background="{TemplateBinding Background}">
                            <ContentPresenter HorizontalAlignment="Stretch"/>
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter TargetName="Border" Property="Background" Value="#34495E"/>
                            </Trigger>
                            <Trigger Property="IsSelected" Value="True">
                                <Setter TargetName="Border" Property="Background" Value="#3498DB"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>
                </Setter.Value>
            </Setter>
        </Style>
        <local:MultiValueConverter x:Key="MultiValueConverter"/>
    </Application.Resources>
</Application>