Please consider that the WordPress standard editor tool does not reflect the font size and that kind of stuff on the front end of the website. It is a tool to make for example a part of the text bold but it will not change for example the font family which is already set in the theme options.
I suggest that you back up your website completely and update the theme to version 6.0.4 and the Cornerstone plugin to version 3.0.4.
Then go to X > Settings and enable the Cornerstone plugin for the posts:
Then you will have the option to add the posts using the Cornerstone. That portion will be available for the single blog posts such as:
For the listing, you need to go to the post editing screen and from top right section click on the Screen Options and enable the Excerpt option. That will bring the excerpt box at the bottom of the screen:
Now whatever you add to that excerpt box will show on the blog listing page as the short description of the blog:
Such as this page: http://epilepsyandmelifestyle.com/blog/