After closing a site banner in Confluence, the sidebar is not readjusted to the top

Issue Summary

This is reproducible on Data Center: (yes) / (no)

Steps to Reproduce

1. Add a close-able site-wide banner, for example, as documented in here
   1. Go to Confluence Admin
   2. Click 'Custom HTML' in the 'Look and Feel' section of the left-hand panel.
   3. Click 'Edit'.
   4. Add the following code to the 'At beginning of the BODY' textbox.

      <div class="aui-message closeable">
          <p class="title">
              <strong>Lorem Ipsum</strong>
          </p>
          <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Orci nulla pellentesque dignissim enim. Fames ac turpis egestas integer eget aliquet nibh. Maecenas sed enim ut sem viverra aliquet eget sit. Quis risus sed vulputate odio ut enim. Leo vel orci porta non pulvinar neque laoreet suspendisse. Eu tincidunt tortor aliquam nulla facilisi cras fermentum. Consequat id porta nibh venenatis. Pharetra convallis posuere morbi leo urna molestie at elementum. Dignissim cras tincidunt lobortis feugiat vivamus.Lorem sed risus ultricies tristique. Pulvinar pellentesque habitant morbi tristique senectus et. Vehicula ipsum a arcu cursus vitae. Nunc consequat interdum varius sit amet mattis. Eget velit aliquet sagittis id consectetur purus ut. Volutpat maecenas volutpat blandit aliquam etiam erat velit scelerisque. Ipsum a arcu cursus vitae congue mauris. Aliquet risus feugiat in ante metus dictum at tempor commodo. Turpis egestas pretium aenean pharetra magna ac placerat vestibulum lectus. Urna molestie at elementum eu. In vitae turpis massa sed elementum. Integer vitae justo eget magna fermentum iaculis eu non diam.Quis vel eros donec ac odio tempor orci. Pulvinar mattis nunc sed blandit libero. Sit amet justo donec enim diam vulputate ut pharetra sit. Pellentesque habitant morbi tristique senectus et. Odio facilisis mauris sit amet massa vitae tortor. Sed id semper risus in hendrerit gravida. Ultrices dui sapien eget mi proin sed libero enim. Urna nunc id cursus metus aliquam eleifend mi. Vel risus commodo viverra maecenas accumsan. Pretium vulputate sapien nec sagittis aliquam malesuada bibendum. Sit amet cursus sit amet dictum sit amet. Ac turpis egestas sed tempus. Blandit turpis cursus in hac habitasse platea dictumst quisque sagittis. Pellentesque elit eget gravida cum sociis natoque penatibus. At augue eget arcu dictum varius duis at. Risus quis varius quam quisque id diam vel quam. Libero volutpat sed cras ornare arcu. Tempor commodo ullamcorper a lacus vestibulum sed arcu non. Netus et malesuada fames ac turpis.</p>
      </div> 

   5. Click 'Save'.
2. Browse to any page under one of your Confluence spaces. 
3. Close the banner

Expected Results

The banner is closed and the sidebar goes to the top of the page. 

Actual Results

The banner is closed, but the sidebar remains placed as before (when the banner was visible) and the spacing between the top bar and the beginning of the sidebar remains empty.

Workaround

Currently there is no known workaround for this behavior.
However, the issue disappears when the user scrolls in the page and the sidebar position is recalculated.