Fix <video> positioning for the MediaSource-based rendering

remoting/webapp/main.css

Index: remoting/webapp/main.css
diff --git a/remoting/webapp/main.css b/remoting/webapp/main.css
index 2e16fbbed0b3ab4749b41849394e12158514c218..ccc5236b72e0d200fe90971dce8368637fc3263e 100644
--- a/remoting/webapp/main.css
+++ b/remoting/webapp/main.css
@@ -722,6 +722,10 @@ html.apps-v2.scrollable {
   height: 100%
 }
 
+.vertically-centered-inner {
+  width: 100%;
+}
+
 .horizontally-centered::before,
 .horizontally-centered::after,
 .vertically-centered::before,
@@ -745,7 +749,6 @@ html.apps-v2.scrollable {
 /* video-container needs relative position so that mediasource-video-output can
  * be positioned relative to the parent with position:absolute. */
 #video-container {
-  width: 100%;
   position: relative;
 }