Well, if the pages cannot be accessed then they cannot be marked
As said, several efforts were made to access it, and on all of these occasions the menu was not available).
That said, I had ANOTHER look at you site. Besides your first page (which incidentally is not a short URL but a link to a page, as in htttp:// my site.com/my_page.php), the rest of the menu links STILL result in a "not found" page. I have special powers. Herewith your links. Note the CaSeS of the files.
Language: HTML
<a href="calc.php">Calc</a> // this file exists
| <a href="String.php">String</a> // string.php exists, but not String.php, resulting in a page not found
| <a href="Array.php">Array</a> //you only have array.php
| <a href="Function.php">Function</a>// you only have function.php
Having stated the above, I fail to see how you can claim that your menu "works"? Your site is not working.