IE 8 issues. Firefox issues

my website is https://www.actdnaanddrug.com/

Currently when the home page loads in IE8, it flushes the slider to the far right of the screen and stacks the pictures on top of one antoher.
It also gives the error message, “page loaded with errors”.

It also looks weird in Firefox as well.

I’m pretty new to coding, so any help is appreciated!
Or if this topic is answered anywhere else, please direct me. I looked through all the topics and couldnt find anything!