Expandable Modal Screen from Quick Action

Modal.cmp

<aura:component implements="force:lightningQuickAction" >
    <aura:attribute name="size" type="string" />
    <aura:html tag="style">
        .slds-modal__container {
            min-width: {!v.size};
        }
    </aura:html>      
    <lightning:button variant="brand" label="Make it big!" title="Make it big!" onclick="{! c.handleBiggly }"/>
    <lightning:button variant="brand" label="Make it tiny!" title="Make it tiny!" onclick="{! c.handleSmally }"/>
</aura:component>

ModalController.js

({
	handleBiggly : function(component, event, helper) {
		component.set("v.size", "90vw");
	},
    handleSmally : function(component, event, helper) {
		component.set("v.size", "30vw");
	}
})