Nilo Velez

System Fonts enqueues a stylesheet that lets you use the native font on each operating system and defines a system-ui css @font-face that you can use on the customizer, your theme’s settings or your own code.
<h4>Usage example</h4>
The Twenty Seventeen theme uses this css selector for the body text:
<pre><code>body, button, input, select, textarea {
 font-family: "Libre Franklin", "Helvetica Neue", helvetica, arial, sans-serif;
}
</code></pre>
We are going to replace it with the default system font. 
In you WordPress site, go to <code>Appearance > Customize > Additional CSS</code> and paste this code
<pre><code>body, button, input, select, textarea {
 font-family: system-ui;
}
</code></pre>
Appart from them font-family, there are other font-properties available:
<ul>
<li>font-style: normal or italic;</li>
<li>font-weight: 300 (light), 400 (regular), 500 (medium), 700 (bold);</li>
</ul>
For example this is the code make an element’s text semibold and cursive:
<pre><code>#my-element {
 font-family: system-ui;
 font-weight: 500;
 font-style: italic;
}
</code></pre>

System Fonts

Enqueues a stylesheet that lets you use the native font on each operating system.

Kostas Vrouvas

This plugin adds the WordPress menu from the admin sidebar under the {site-name} menu on the front-end WordPress toolbar.
Feedback is much appreciated.

Front-end Toolbar

This plugin adds all WordPress pages from the admin sidebar under the "site-name" menu on the front-end.

System Fonts vs Front-end Toolbar