Shaker/Avalonia/SukiUI/Theme/TextStyles.axaml

<Styles xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    
    <Styles.Resources>
        <FontFamily x:Key="DefaultFontFamily">avares://SukiUI/CustomFont#Quicksand</FontFamily>
        <FontWeight x:Key="DefaultDemiBold">DemiBold</FontWeight>
    </Styles.Resources>
    
    <Style Selector="TextBlock, TextBox, Button, RadioButton, DropDownButton">
        <Setter Property="TextBlock.FontFamily" Value="{DynamicResource DefaultFontFamily}"/>
    </Style>
	
</Styles>