Revert (some of) "replace setup vr button with webvr/webxr info text"

This reverts parts of commit df876b1.

src/html/index.html

@@ -109,9 +109,9 @@ <h1>Konterball</h1>
 
   <div class="choose-vr-mode-screen">
     <div class="inner">
+      <div class="cardboard" id="cardboard"></div>
       <div class="tilt">
-        <p>We're updating WebVR to WebXR. In the meantime, <span id="tilt"><span class="before"></span><span class="main">check out this experiment in 360</span></span>.
-        </p>
+        <p><span id="tilt"><span class="before"></span><span class="main">Try it without a headset</span></span> or <a href="https://webvr.info/" target="_blank"><span class="before"></span><span class="main">get set up in VR.</span></a></p>
       </div>
     </div>
   </div>

src/javascripts/app.js

@@ -101,6 +101,7 @@ class PingPong {
       this.loadModeChooserAnimation(),
       this.loadingAnimation(),
     ]).then(() => {
+      this.setupVRButton();
       this.introAnimation();
     }).catch(e => {
       console.warn(e);