Authoritaters asked how to do this. There are 2 ways it can be done. The easiest was is to go to – Customise – Layout – Fonts and Colours
The 2nd way involves editing the code.
If you go to Edit HTML and add this piece of code:
border: 0 !important;
You can put it in anywhere as long as its after the bit that says – head – shown below.
The Head can be found near the top of the page of code. I just scrolled down until I found a blank line and pasted the code in, saved it and and it works. I have a spare practice blog where I do all my experimenting, otherwise you should save your Template before you play with the Code in case it all goes horribly wrong!