Is your feature request related to a problem? Please describe.

Looking at an installation of 03 Aug 2019 nightly build Joomla_4.0.0-alpha11-dev-Development-Full_Package

In the admin editor (Codemirror) when editing index.php, for example, there are several editor buttons that run onto a second row. It looks rather messy, with the two rows touching each each other and a gap at the beginning of the second row:

Describe the solution you'd like

Tidy up the CSS. I have no idea where this code comes from, but using the Firefox inspector I can recommend the following changes end up in template.min.css and/or the html code:

Where the html is
<div id="subhead" class="subhead">
change the associated CSS from
.subhead { padding: 13px 0; }
to
.subhead { padding: 13px 0 5px 0; }

Then, where applicable to html code like this:
<button class="btn btn-primary" data-toggle="modal" data-target="[various options]">
change CSS from
.subhead .btn-toolbar > * { margin-left: .75rem; }
to:
.subhead .btn-toolbar > * { margin-right: .75rem; margin-bottom: .5rem; /* new code added */ }

After this, there is no longer any need for the first-child left margin CSS:
.subhead .btn-toolbar > :first-child { margin-left: 0; }

and,
EITHER add a new class to right-align the help button:
#toolbar-help { margin-right: 0; }
OR, change the html:
<joomla-toolbar-button id="toolbar-help" class="ml-auto"> to
<joomla-toolbar-button id="toolbar-help" class="ml-auto mr-0">

It will now all look like this:

Additional context

This could possibly apply to other areas of the Admin panel.