Internet Exporer 8 not showing the home page properly

This website http://bgen.org.uk.gridhosted.co.uk/ is using twenty fourteen theme with some customisation . It works fine except in internet explorer 8 which shows a mostly black screen on the home page and some layout issues with the sidebar on the Resources page and the Our Members page.
I have made some simple code changes to header.php as per advice on some forums but this has made no difference. Any more ideas?
Thanks
Sarah