[Glitch] Fix emoji picker button scrolling with textarea content in single-column view (#2501)

Port bbea052935 to glitch-soc

Signed-off-by: Claire <claire.github-309c@sitedethib.com>

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

@@ -1240,6 +1240,7 @@ $ui-header-height: 55px;
   border-radius: 4px;
   transition: box-shadow 300ms linear;
   min-height: 0;
+  position: relative;
 
   &.active {
     transition: none;