Custom view background using attrs causes crash

I've been experimenting with styles in Android recently (and blatantly failed) trying to use attrs in custom view background resources. So basically, I want to make the user set a custom theme if he or she wants to. I have a main fragment which hosts a (support) ViewPager. Each page in the ViewPager gets inflated with a custom view using a custom background. The view's background points to a style reference which is basically a color justified by the selected theme.

Attributes

<attr name="designBase400" format="reference" />
<attr name="designBase500" format="reference" />
<attr name="designBase700" format="reference" />

One of the few custom styles

<style name="Theme.ColorScheme.Turquoise" parent="AppTheme">
    <item name="designBase400">@color/design_base_400_turquoise</item>
    <item name="designBase500">@color/design_base_500_turquoise</item>
    <item name="designBase700">@color/design_base_700_turquoise</item>
</style>

<style name="AppTheme" parent="AppBaseTheme">
    <item name="windowActionBar">false</item>
    <item name="android:spinnerItemStyle">@style/SpinnerItem</item>
    <item name="android:spinnerDropDownItemStyle">@style/SpinnerItem.DropDownItem</item>
</style>

Corresponding colors

<color name="design_base_500_turquoise">#009688</color>
<color name="design_base_700_turquoise">#00796B</color>
<color name="design_base_400_turquoise">#26A69A</color>

Background resource

<shape xmlns:android="http://ift.tt/nIICcg" android:shape="oval">
    <solid android:color="?attr/designBase400" />
</shape>

The view using the background resource (only the important part)

<RelativeLayout
    android:id="@+id/view_entry_hour_container"
    android:layout_width="@dimen/entry_view_circle_dimen"
    android:layout_height="@dimen/entry_view_circle_dimen"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:layout_centerVertical="false"
    android:background="@drawable/background_circle" >

    <TextView
        android:id="@+id/view_entry_hour"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="false"
        android:layout_alignParentStart="false"
        android:layout_centerHorizontal="true"
        android:layout_centerInParent="true"
        android:layout_centerVertical="true"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:textColor="@android:color/white"
        android:textSize="@dimen/entry_view_hour_size"
        android:textStyle="bold" />

</RelativeLayout>

Now I have a sample theme set in the ApplicationManifest.xml (say @style/Theme.ColorScheme.Turquoise) and the application crashes immediately, raising an InflationException. The stack trace can be found here. I don't have the foggiest idea on what could have went wrong.