How do I extend multiple interfaces in aura:application. 

I want to use ltng:out and force:slds in the same app and expose the app on a public website. As a workaround I downloaded the slds class into static resource referenced through ltng: require for now

When I try to save this code in developer console:

    <aura:application extends="force:slds,ltng:outApp" access="GLOBAL">
        <aura:dependency resource="c:casesearch"/>
    </aura:application>


I get the following error:

[![enter image description here][1]][1]



  [1]: https://i.sstatic.net/DInBw.jpg