HandyControl/src/Shared/HandyControl_Shared/Themes/Styles/DateTimePicker.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:hc="clr-namespace:HandyControl.Controls">

    <Style BasedOn="{StaticResource DateTimePickerBaseStyle}" TargetType="hc:DateTimePicker"/>

    <Style x:Key="DateTimePicker.Small" BasedOn="{StaticResource DateTimePickerBaseStyle}" TargetType="hc:DateTimePicker">
        <Setter Property="MinHeight" Value="20"/>
        <Setter Property="Padding" Value="6,0"/>
    </Style>

    <Style x:Key="DateTimePickerExtend" BasedOn="{StaticResource DateTimePickerExtendBaseStyle}" TargetType="hc:DateTimePicker"/>

    <Style x:Key="DateTimePickerExtend.Small" BasedOn="{StaticResource DateTimePickerExtend}" TargetType="hc:DateTimePicker">
        <Setter Property="hc:InfoElement.MinContentHeight" Value="20"/>
        <Setter Property="hc:InfoElement.ContentHeight" Value="20"/>
        <Setter Property="hc:TitleElement.MarginOnTheLeft" Value="0,3,6,0"/>
        <Setter Property="hc:TitleElement.MarginOnTheTop" Value="6,0,0,1" />
        <Setter Property="Padding" Value="6,0"/>
        <Setter Property="MinHeight" Value="20" />
    </Style>

    <Style x:Key="DateTimePickerPlus" BasedOn="{StaticResource DateTimePickerPlusBaseStyle}" TargetType="hc:DateTimePicker"/>

    <Style x:Key="DateTimePickerPlus.Small" BasedOn="{StaticResource DateTimePickerPlus}" TargetType="hc:DateTimePicker">
        <Setter Property="hc:InfoElement.MinContentHeight" Value="20"/>
        <Setter Property="hc:InfoElement.ContentHeight" Value="20"/>
        <Setter Property="hc:TitleElement.MarginOnTheLeft" Value="0,3,6,0"/>
        <Setter Property="hc:TitleElement.MarginOnTheTop" Value="6,0,0,1" />
        <Setter Property="Padding" Value="6,0"/>
        <Setter Property="MinHeight" Value="20" />
    </Style>

</ResourceDictionary>