Site suddenly stopped formatting in IE but works in Firefox

I’m in the process of building a travel site on wordpress but have encountered an issue with the formatting on internet explorer.

It was all looking absolutely fine then I amended one word in the index.php file which messed up the formatting so I amended straight back but ever since it’s now all over the place on IE. I’ve gone right back to the original index.php code but that still hasn’t seen any improvements.

I’m using the travel reliance theme on the URL http://www.travelinspector.co.uk

Does anyone have any ideas on how ti fix this? I know there can be issues between IE and Firefox but it’s strange that it was working fine then suddenly the formatting is all gone.

Any help would be greatly appreciated.

Thanks