Fix offset inside iframe body caused by Gin Toolbar
>>> [!note] Migrated issue
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<!-- Migrated from issue #3559956. -->
Reported by: [norman.lol](https://www.drupal.org/user/2482808)
Related to !145 !148
>>>
<h3 id="summary-problem-motivation">Problem/Motivation</h3>
<p>The new default vertical toolbar from Gin Toolbar adds an undesired offset to the top of the frontend editing sidebar.</p>
<p>Removing the <code>.gin--navigation</code> class from the body inside the iframe resolves this issue.</p>
<p><img src="https://www.drupal.org/files/issues/2025-11-26/Screenshot%202025-11-26%20at%2000.53.52.png" alt="Screenshot of undesired spacing offset"></p>
<h4 id="summary-steps-reproduce">Steps to reproduce</h4>
<h3 id="summary-proposed-resolution">Proposed resolution</h3>
<p>Skip or override <code>gin_toolbar_preprocess_html</code> where this class gets added.</p>
<h3 id="summary-remaining-tasks">Remaining tasks</h3>
<h3 id="summary-ui-changes">User interface changes</h3>
<h3 id="summary-api-changes">API changes</h3>
<h3 id="summary-data-model-changes">Data model changes</h3>
issue