Prevent "UP | HOME" links from being hidden by TOC

[tfree87]

I finally created a pull request to fix the issue I posted (#150).

This change in the CSS prevents the HOME and UP links from being hidden when using ReadTheOrg theme.

I tested this change in the CSS and verified that it works by adding the following to my Org files:

#+OPTIONS: html-style:nil
#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="https://tfree87.github.io/org-html-themes/src/readtheorg_theme/css/htmlize.css"/>
#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="https://tfree87.github.io/org-html-themes/src/readtheorg_theme/css/readtheorg.css"/>

#+HTML_HEAD: <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
#+HTML_HEAD: <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.4/js/bootstrap.min.js"></script>
#+HTML_HEAD: <script type="text/javascript" src="https://fniessen.github.io/org-html-themes/src/lib/js/jquery.stickytableheaders.min.js"></script>
#+HTML_HEAD: <script type="text/javascript" src="https://fniessen.github.io/org-html-themes/src/readtheorg_theme/js/readtheorg.js"></script>

The above code produced the expected result.

Thanks for all your work on this neat project!

[fniessen]

Dear @tfree87 , thank you very much!