[Glitch] Set max-width and max-height to gif video

Port c5c8f68031 to glitch-soc

Signed-off-by: Thibaut Girka <thib@sitedethib.com>

app/javascript/flavours/glitch/styles/components/media.scss

@@ -691,3 +691,10 @@
     }
   }
 }
+
+.gifv {
+  video {
+    max-width: 100vw;
+    max-height: 80vh;
+  }
+}