hiratatsuya

CSS and JS Enqueuer plugin will enable to enqueue external CSS and JS, and edit it. 
You can customize the web site at only the dashboard.

CSS and JS Enqueuer

CSS and JS Enqueuer plugin will enable to enqueue  external CSS and JS, and edit it.

arickards

tinyWYM Editor was created to help inexperienced WordPress users create cleaner, more semantic markup, and to avoid some of the pitfalls of WordPress’s standard WYSIWYG editor. It does this by labelling and highlighting all HTML elements in the editor, creating a visual representation of the HTML being generated.
tinyWYM Editor also gives more experience users all the control and flexibility of the text editor without having to leave the visual editor. Create and edit any HTML element, add attributes, and wrap or unwrap elements all from the visual editor.
See the <a href="https://wordpress.org/plugins/tinywym-editor/screenshots/" title="Screenshots" rel="ugc">Screenshots</a> and <a href="https://wordpress.org/plugins/tinywym-editor/faq/" title="Frequently Asked Questions" rel="ugc">FAQ</a> sections for details on how to use tinyWYM Editor.

tinyWYM Editor

At long last: Now we can see the container hierarchy while editing visually, and manipulate it too!
The plugin author is quick to respond, clear friendly and helpful.
Unreserved recommendation!



Fantastic

Convert WordPress's WYSIWYG editor into a WYSIWYM editor. Add and edit any HTML tag and attribute from the visual editor.

CSS and JS Enqueuer vs tinyWYM Editor