App.axaml

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="TransitLab.App"
             xmlns:local="using:TransitLab"
             xmlns:converters="using:TransitLab.Converters"
             RequestedThemeVariant="Dark">

    <Application.DataTemplates>
        <local:ViewLocator/>
    </Application.DataTemplates>

    <Application.Resources>
        <ResourceDictionary>
            <!-- ── Converters ─────────────────────────────────────────────── -->
            <converters:StatusBrushConverter x:Key="StatusBrushConverter"/>

            <!-- ── Nord colour palette ─────────────────────────────────────── -->
            <SolidColorBrush x:Key="BrushBg"      Color="#2e3440"/>
            <SolidColorBrush x:Key="BrushBg2"     Color="#3b4252"/>
            <SolidColorBrush x:Key="BrushField"   Color="#434c5e"/>
            <SolidColorBrush x:Key="BrushFg"      Color="#eceff4"/>
            <SolidColorBrush x:Key="BrushAccent"  Color="#88c0d0"/>
            <SolidColorBrush x:Key="BrushHint"    Color="#8892a0"/>
            <SolidColorBrush x:Key="BrushBtn"     Color="#5e81ac"/>
            <SolidColorBrush x:Key="BrushBtnHov"  Color="#81a1c1"/>
            <SolidColorBrush x:Key="BrushSep"     Color="#4c566a"/>
            <SolidColorBrush x:Key="BrushWarn"    Color="#ebcb8b"/>
            <SolidColorBrush x:Key="BrushOk"      Color="#a3be8c"/>
            <SolidColorBrush x:Key="BrushErr"     Color="#bf616a"/>
        </ResourceDictionary>
    </Application.Resources>

    <Application.Styles>
        <FluentTheme/>
        <StyleInclude Source="avares://Avalonia.Controls.DataGrid/Themes/Fluent.xaml"/>

        <!-- ── Window background ──────────────────────────────────────────── -->
        <Style Selector="Window">
            <Setter Property="Background" Value="{StaticResource BrushBg}"/>
            <Setter Property="FontFamily" Value="Arial"/>
        </Style>

        <!-- ── TextBlock classes ──────────────────────────────────────────── -->
        <Style Selector="TextBlock">
            <Setter Property="Foreground" Value="{StaticResource BrushFg}"/>
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="20"/>
        </Style>
        <Style Selector="TextBlock.title">
            <Setter Property="FontSize"   Value="26"/>
            <Setter Property="FontWeight" Value="Bold"/>
        </Style>
        <Style Selector="TextBlock.h2">
            <Setter Property="FontSize"   Value="20"/>
            <Setter Property="FontWeight" Value="Bold"/>
            <Setter Property="Foreground" Value="{StaticResource BrushAccent}"/>
        </Style>
        <Style Selector="TextBlock.hint">
            <Setter Property="FontSize"   Value="17"/>
            <Setter Property="FontStyle"  Value="Italic"/>
            <Setter Property="Foreground" Value="{StaticResource BrushHint}"/>
        </Style>
        <Style Selector="TextBlock.warn">
            <Setter Property="FontSize"   Value="17"/>
            <Setter Property="Foreground" Value="{StaticResource BrushWarn}"/>
        </Style>
        <Style Selector="TextBlock.ok">
            <Setter Property="FontSize"   Value="17"/>
            <Setter Property="Foreground" Value="{StaticResource BrushOk}"/>
        </Style>
        <Style Selector="TextBlock.err">
            <Setter Property="FontSize"   Value="17"/>
            <Setter Property="Foreground" Value="{StaticResource BrushErr}"/>
        </Style>

        <!-- ── Input controls ─────────────────────────────────────────────── -->
        <Style Selector="TextBox">
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="20"/>
        </Style>
        <Style Selector="ComboBox">
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="20"/>
        </Style>
        <Style Selector="NumericUpDown">
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="20"/>
        </Style>
        <Style Selector="CheckBox">
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="20"/>
        </Style>

        <!-- ── Toolbar buttons ────────────────────────────────────────────── -->
        <Style Selector="Button.toolbar">
            <Setter Property="Background"  Value="{StaticResource BrushBtn}"/>
            <Setter Property="Foreground"  Value="{StaticResource BrushFg}"/>
            <Setter Property="FontFamily"  Value="Arial"/>
            <Setter Property="FontSize"    Value="18"/>
            <Setter Property="FontWeight"  Value="Bold"/>
            <Setter Property="Padding"     Value="12,6"/>
            <Setter Property="CornerRadius" Value="4"/>
        </Style>
        <Style Selector="Button.toolbar:pointerover /template/ ContentPresenter">
            <Setter Property="Background" Value="{StaticResource BrushBtnHov}"/>
        </Style>

        <!-- ── Primary action button (Save &amp; Run) ─────────────────────── -->
        <Style Selector="Button.primary">
            <Setter Property="Background"  Value="{StaticResource BrushAccent}"/>
            <Setter Property="Foreground"  Value="{StaticResource BrushBg}"/>
            <Setter Property="FontFamily"  Value="Arial"/>
            <Setter Property="FontSize"    Value="18"/>
            <Setter Property="FontWeight"  Value="Bold"/>
            <Setter Property="Padding"     Value="14,6"/>
            <Setter Property="CornerRadius" Value="4"/>
        </Style>
        <Style Selector="Button.primary:pointerover /template/ ContentPresenter">
            <Setter Property="Background" Value="{StaticResource BrushBtnHov}"/>
        </Style>

        <!-- ── NumericUpDown spinner: decrease on left, increase on right ─────── -->
        <Style Selector="NumericUpDown /template/ ButtonSpinner /template/ RepeatButton#PART_IncreaseButton">
            <Setter Property="Grid.Column" Value="1"/>
        </Style>
        <Style Selector="NumericUpDown /template/ ButtonSpinner /template/ RepeatButton#PART_DecreaseButton">
            <Setter Property="Grid.Column" Value="0"/>
        </Style>

        <!-- ── Menu bar ───────────────────────────────────────────────────── -->
        <Style Selector="MenuItem">
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="30"/>
        </Style>

        <!-- ── TabControl / TabItem ───────────────────────────────────────── -->
        <Style Selector="TabControl">
            <Setter Property="Background" Value="{StaticResource BrushBg}"/>
            <Setter Property="Padding"    Value="10,4,10,0"/>
        </Style>
        <Style Selector="TabItem">
            <Setter Property="FontFamily" Value="Arial"/>
            <Setter Property="FontSize"   Value="20"/>
            <Setter Property="Foreground" Value="{StaticResource BrushHint}"/>
            <Setter Property="Padding"    Value="12,6"/>
        </Style>
        <Style Selector="TabItem:selected">
            <Setter Property="Foreground" Value="{StaticResource BrushAccent}"/>
        </Style>
    </Application.Styles>

</Application>