fully hide header buttons if topic is visible (#7203)

fully hide header buttons if topic is visible (#7203)

diff --git a/app/assets/stylesheets/mobile/header.scss b/app/assets/stylesheets/mobile/header.scss
index f72f142..a812836 100644
--- a/app/assets/stylesheets/mobile/header.scss
+++ b/app/assets/stylesheets/mobile/header.scss
@@ -54,6 +54,9 @@
   .extra-info-wrapper + .panel {
     flex: 0;
     min-width: 0;
+    .header-buttons {
+      display: none;
+    }
   }
   // Fade in header avatar + icons if topic title is not visible in mobile header
   .panel {

GitHub sha: 533fb001