text links results should be consistent, on the main page you have some that link to other pages and one that opens a pdf. you should tell visitors before you do things that they might not expect.
you should disable the menu button that links to the current page to prevent visitors accidentally reloading the page they were already on.
again, be consistent with text links. on the 'About the course' page you have some text links blue underlined and some red but both link to other pages. if you are going to make some different to others it should be because they have different results, such as navigating around the page you are on or opening a pdf, so visitors are clear about which links do what.
also, your text links would benefit from a discernably different hover state to help visually impaired visitors tell that they are links.
access keys would also improve accessibility for visitors who cant navigate by mouse.
other than those few coding and usability issues it looks like a very effective and useful site. the navigation seems clear, which is really important, and the design doesnt get in the way of reading the content.