[Glitch] Highlight border when focusing poll-form footer

Port eb551c480d to glitch-soc

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

app/javascript/flavours/glitch/styles/polls.scss

@@ -185,6 +185,10 @@
     select {
       width: 100%;
       flex: 1 1 50%;
+
+      &:focus {
+        border-color: $highlight-text-color;
+      }
     }
   }