Allow adding multiple space-separated classes for openClass

lib/src/index.js

@@ -56,9 +56,10 @@ const MicroModal = (() => {
     }
 
     showModal (event = null) {
+      const openClass = this.config.openClass.split(' ')
       this.activeElement = document.activeElement
       this.modal.setAttribute('aria-hidden', 'false')
-      this.modal.classList.add(this.config.openClass)
+      this.modal.classList.add(...openClass)
       this.scrollBehaviour('disable')
       this.addEventListeners()
 
@@ -85,14 +86,14 @@ const MicroModal = (() => {
       }
       this.config.onClose(this.modal, this.activeElement, event)
 
+      let openClass = this.config.openClass.split(' ') // <- old school ftw
       if (this.config.awaitCloseAnimation) {
-        let openClass = this.config.openClass // <- old school ftw
         this.modal.addEventListener('animationend', function handler () {
-          modal.classList.remove(openClass)
+          modal.classList.remove(...openClass)
           modal.removeEventListener('animationend', handler, false)
         }, false)
       } else {
-        modal.classList.remove(this.config.openClass)
+        modal.classList.remove(...openClass)
       }
     }