Hi Mauno,
Sorry, I understood what you were trying to say and wrote inline styles instead of putting the css in style tags. I can now see the arrow on my HTML block where previously I could see nothing, thanks. I can't see the blocks (which are generated using javascript) though. Do you think there is a problem with the way I have included the scripts too? I found a solution on the link (http://docs.moodle.org/dev/Using_jQuery_with_Moodle_2.0) you gave me, but it says you have to include them in the header php file. I am not sure where exactly I should add them and I don't think that will work..