Fix style regressions (#3062)

From #2327 - Elephant friend was overlapping with text, oversized in
single column layout

From #2021 - Centered layout goes against design principles, changes
UX for everybody who's already used to the current one

From #2271 - CPU/RAM overusage from keeping columns in DOM (fix #2648,
possibly also #2101)

app/javascript/styles/containers.scss

@@ -9,16 +9,6 @@
   }
 }
 
-.mastodon-column-container {
-  display: flex;
-  height: 100%;
-  width: 100%;
-
-  // 707568 - height 100% doesn't work on child of a flex item - chromium - Monorail
-  // https://bugs.chromium.org/p/chromium/issues/detail?id=707568
-  flex: 1 1 auto;
-}
-
 .logo-container {
   max-width: 400px;
   margin: 100px auto;