apex:slds tag works in Lightning Experience where as it is not working in Napili Community.This visualforce page is added as action button.
<apex:page standardController="Account">
<apex:slds/>
<apex:pageBlock >
<apex:pageblockSection columns="2">
<apex:outputField value="{!Account.Name}"/>
<apex:outputField value="{!Account.Type}"/>
<apex:outputField value="{!Account.BillingStreet}"/>
<apex:outputField value="{!Account.BillingCity}"/>
<apex:outputField value="{!Account.BillingState}"/>
</apex:pageblockSection>
</apex:pageBlock>
</apex:page>