Theming

ModernUi resolves every colour, font and metric from resource keys injected into the window when you call ModernUi.Apply (or construct a ModernWindow). Your own XAML can reference the same keys with {DynamicResource ...}.

Theme

Theme selects the built-in palette:

ModernUi.Apply(window, Theme.Light); // or Theme.Dark

Palette

ThemePalette is the single source of truth for colours. Each property maps to a Brush.* key:

Property	Light / Dark	Key	Use
`Background`	`#f5f5f5#3b4453`	`Brush.Background`	Window base
`Panel`	`#d9d9d9#4b5463`	`Brush.Panel`	Cards / surfaces
`Control`	`#ffffff#2c3340`	`Brush.Control`	Input field background
`Foreground`	`#1e1e1e#f5f5f5`	`Brush.Foreground`	Primary text
`ForegroundMuted`	`#6a6a6a#c8c8c8`	`Brush.ForegroundMuted`	Secondary text
`Border`	`#c0c0c0#2c3340`	`Brush.Border`	Dividers / outlines
`Accent`	`#0696d7#0696d7`	`Brush.Accent`	Primary buttons, focus
`AccentMuted`	`#f2f2f2#3a7292`	`Brush.AccentMuted`	Subtle hover background
`Error`	`#ec4a41#ec4a41`	`Brush.Error`	Destructive / error
`Success`	`#3fb950#3fb950`	`Brush.Success`	Positive status (optional, has a default)
`Warning`	`#d29922#d29922`	`Brush.Warning`	Caution status (optional, has a default)

Each colour is also exposed as a raw Color.* key (for gradient stops and animations). Success and Warning are optional record members with library defaults - toasts, the warning dialog icon and the BadgeSuccess / BadgeWarning styles all follow them.

Custom accent

Copy a default palette and override only what you need:

ThemePalette palette = ThemePalette.Dark with
{
    Accent = (Color)ColorConverter.ConvertFromString("#FF8A00"),
};

ModernUi.Apply(window, Theme.Dark, palette);

Full custom palette

To re-skin completely, build a ThemePalette from scratch - every property is required, so the compiler makes sure you set all nine colours. Pass it to ModernUi.Apply (or a ModernWindow constructor, or ModernMessageBox / ModernToast).

using System.Windows.Media;

static Color Hex(string hex) => (Color)ColorConverter.ConvertFromString(hex)!;

// A "Tokyo Night" palette - nothing to do with the Inventor defaults.
var palette = new ThemePalette
{
    Background      = Hex("#1a1b26"), // window base
    Panel           = Hex("#24283b"), // cards / surfaces
    Control         = Hex("#1f2335"), // input backgrounds
    Foreground      = Hex("#c0caf5"), // primary text
    ForegroundMuted = Hex("#565f89"), // secondary text
    Border          = Hex("#2f334d"), // dividers / outlines
    Accent          = Hex("#7aa2f7"), // primary buttons, focus
    AccentMuted     = Hex("#3d59a1"), // hover / selection
    Error           = Hex("#f7768e"), // destructive / error
};

// The Theme argument only picks a default palette, so it is ignored once you pass your own -
// use either value.
ModernUi.Apply(window, Theme.Dark, palette);

The same controls, rendered under that palette:

Font

FontOptions sets the family and base size, exposed as Font.* keys (Font.Family, Font.Size.Normal, Font.Size.Small, Font.Size.Title).

// From Inventor's UI font (points are converted to DIPs):
FontOptions font = FontOptions.FromInventor(app.GeneralOptions.TextAppearance, app.GeneralOptions.TextSize);

// Or the Windows system font:
FontOptions fallback = FontOptions.Default;

ModernUi.Apply(window, Theme.Dark, font: font);

Design tokens

Non-colour metrics are static keys you can reuse for consistent spacing and corners:

Key	Type	Value
`Radius.Control`	CornerRadius	4
`Radius.Card`	CornerRadius	6
`Size.ControlHeight`	double	30
`Size.ControlHeightLarge`	double	35
`Padding.Control`	Thickness	10,6
`Padding.Card`	Thickness	16
`Margin.Stack`	Thickness	0,0,0,8

<Border Background="{DynamicResource Brush.Panel}"
        CornerRadius="{DynamicResource Radius.Card}"
        Padding="{DynamicResource Padding.Card}">
  <TextBlock Foreground="{DynamicResource Brush.Foreground}" Text="Themed surface" />
</Border>

Switch theme at runtime

ModernUi.SetTheme re-colours an already-themed window live (all styles use DynamicResource, so no reload is needed):

ModernUi.SetTheme(window, Theme.Light);