Use progress event instead of canplay to adjust for iOS

Author: thekid

src/main/handlebars/layout.handlebars

@@ -330,7 +330,7 @@
         scale: 0;
       }
 
-      &.loading::after {
+      &.loading::after, &:buffering::after {
         content: url('/static/loading.svg');
       }
     }

src/main/js/lightbox.js

@@ -64,7 +64,7 @@ class Lightbox {
 
       // Simulate :playing pseudo-class
       const $video = $display.querySelector('video');
-      $video.addEventListener('canplay', e => $display.classList.remove('loading'));
+      $video.addEventListener('progress', e => $display.classList.remove('loading'));
       $video.addEventListener('play', e => $display.classList.add('playing'));
       $video.addEventListener('pause', e => $display.classList.remove('playing'));
       $video.addEventListener('ended', e => $display.classList.remove('playing'));