Template misaligned?

Hi I have been running my site for a few months now, and all seemed well until this morning, i noticed that the navigation on my site has “moved” and that it was covering part of the title?? in internet explorer 8 ( it is fine in chrome and firefox)

https://www.dating-review-uk.co.uk/blog

I am terrible at PHP, but if this was HTML I would assumed an unclosed [div] was the problem.

However since I put this site together a while ago, and only really looked up how to modify the theme as an when I needed to, I am a little stuck as to how to fix this.

can someone help me to identify the file that I need to look at to sort this out, I assumed that it would be a css for functions file is this correct?