WP File Manager

Name	Action
..
block.json	Edit
editor-rtl.css	Edit
editor-rtl.min.css	Edit
editor.css	Edit
editor.min.css	Edit
style-rtl.css	Edit
style-rtl.min.css	Edit
style.css	Edit
style.min.css	Edit
theme-rtl.css	Edit
theme-rtl.min.css	Edit
theme.css	Edit
theme.min.css	Edit

Editing: editor.min.css

.wp-block-audio{margin-left:0;margin-right:0;position:relative}.wp-block-audio.is-transient audio{opacity:.3}.wp-block-audio .components-spinner{left:50%;margin-left:-9px;margin-top:-9px;position:absolute;top:50%}