Thank you for the credentials, but it has no admin rights, so we can not check your pages.
Did you add something on your header or footer recently? Can you audit all your custom HTML tags and/or CSS code you added recently to check for syntax error.
And if you have not done yet, please do a testing for a plugin conflict. You can do this by deactivating all third-party plugins, and seeing if the problem remains. If it's fixed, you'll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
Let us know how it goes,