Line-height of text in wp-admin

This is the CSS you will need:

* {
  line-height: 1.6;
}

You could add this at “Customize” -> “Additional CSS” but notice that this will affect all elements because of the “*”. You can see more selectors here, for example if you only want it to affect the content of posts, you would do:

.entry-content {
  line-height: 1.6;
}

You can add “!important” to ignore the css hierarchy like so:

.entry-content {
  line-height: 1.6 !important;
}

You can see the ids and classes of certain elements by using the element inspector of your browser e.g. “f12” on firefox, clicking on the button shown in the image below and then clicking on the element of the page you are interested in.

If you are only interested in the wp-admin page, you could use the hook below in your plugin code:

add_action( 'admin_head', 'asd_set_custom_line_height' );
function asd_set_custom_line_height(){
    echo "
    <style type="text/css">
    * {
        line-height: 1.6;
    }
    </style>
    ";
}