2. App.xaml を変更する
<ApplicationResources>
<ResourceDictionary>
<ResourceDictionaryMergedDictionaries>
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Controls.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Fonts.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Colors.xaml" />
<ResourceDictionary Source="pack://application:,,,/MahApps.Metro;component/Styles/Accents/BaseLight.xaml" />
<ResourceDictionary Source="pack://application:,,,/MaterialDesignThemes.Wpf;component/Themes/MaterialDesignTheme.Light.xaml" />
<ResourceDictionary Source="pack://application:,,,/MaterialDesignThemes.Wpf;component/Themes/MaterialDesignTheme.Defaults.xaml" />
<ResourceDictionary Source="pack://application:,,,/MaterialDesignColors;component/Themes/Recommended/Primary/MaterialDesignColor.DeepPurple.xaml" />
<ResourceDictionary Source="pack://application:,,,/MaterialDesignColors;component/Themes/Recommended/Accent/MaterialDesignColor.Lime.xaml" />
<ResourceDictionary Source="pack://application:,,,/MaterialDesignThemes.MahApps;component/Themes/MaterialDesignTheme.MahApps.Fonts.xaml" />
<ResourceDictionary Source="pack://application:,,,/MaterialDesignThemes.MahApps;component/Themes/MaterialDesignTheme.MahApps.Flyout.xaml" />
</ResourceDictionaryMergedDictionaries>
<SolidColorBrush xKey="HighlightBrush" Color="{DynamicResource Primary700}"/>
<SolidColorBrush xKey="AccentBaseColorBrush" Color="{DynamicResource Primary600}" />
<SolidColorBrush xKey="AccentColorBrush" Color="{DynamicResource Primary500}"/>
<SolidColorBrush xKey="AccentColorBrush2" Color="{DynamicResource Primary400}"/>
<SolidColorBrush xKey="AccentColorBrush3" Color="{DynamicResource Primary300}"/>
<SolidColorBrush xKey="AccentColorBrush4" Color="{DynamicResource Primary200}"/>
<SolidColorBrush xKey="WindowTitleColorBrush" Color="{DynamicResource Primary700}"/>
<SolidColorBrush xKey="AccentSelectedColorBrush" Color="{DynamicResource Primary500Foreground}"/>
<LinearGradientBrush xKey="ProgressBrush" EndPoint="0.001,0.5" StartPoint="1.002,0.5">
<GradientStop Color="{DynamicResource Primary700}" Offset="0"/>
<GradientStop Color="{DynamicResource Primary300}" Offset="1"/>
</LinearGradientBrush>
<SolidColorBrush xKey="CheckmarkFill" Color="{DynamicResource Primary500}"/>
<SolidColorBrush xKey="RightArrowFill" Color="{DynamicResource Primary500}"/>
<SolidColorBrush xKey="IdealForegroundColorBrush" Color="{DynamicResource Primary500Foreground}"/>
<SolidColorBrush xKey="IdealForegroundDisabledBrush" Color="{DynamicResource Primary500}" Opacity="0.4"/>
<SolidColorBrush xKey="MahApps.Metro.Brushes.ToggleSwitchButton.OnSwitchBrush.Win10" Color="{DynamicResource Primary500}" />
<SolidColorBrush xKey="MahApps.Metro.Brushes.ToggleSwitchButton.OnSwitchMouseOverBrush.Win10" Color="{DynamicResource Primary400}" />
<SolidColorBrush xKey="MahApps.Metro.Brushes.ToggleSwitchButton.ThumbIndicatorCheckedBrush.Win10" Color="{DynamicResource Primary500Foreground}" />
</ResourceDictionary>
</ApplicationResources>
3. MainWindow.xaml を変更する
<metroMetroWindow
...
xmlnsmetro="http://metro.mahapps.com/winfx/xaml/controls"
GlowBrush="{DynamicResource AccentColorBrush}"
BorderThickness="1"
Title="MainWindow" Height="200" Width="300">
<Grid>
<Button Content="Button" HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" Width="75"/>
</Grid>
</metroMetroWindow>