[Glitch] Change onboarding prompt to use full width of banner in web UI

Port 1f141f656d to glitch-soc

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

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

@@ -985,7 +985,6 @@ $ui-header-height: 55px;
   border-radius: 8px;
   border: 1px solid $highlight-text-color;
   background: rgba($highlight-text-color, 0.15);
-  padding-inline-end: 45px;
   overflow: hidden;
 
   &__background-image {
@@ -1048,7 +1047,7 @@ $ui-header-height: 55px;
     position: absolute;
     inset-inline-end: 0;
     top: 0;
-    padding: 10px;
+    padding: 15px 10px;
 
     .icon-button {
       color: $highlight-text-color;