You have
.post {
width: 875px;
}
in your child theme style.css. Remove width property from child theme style sheet.
Quote:
Also, my front page slider is not working either.
WordPress bundled jQuery is being loaded at all in your site. But some plugin/script is loading jQuery from both Google CDN and http://code.jquery.com. Find that plugin/script and remove it. Or, you can use Restore jQuery plugin to restore bundled jQuery.
Your header menu is very impressive BTW, 🙂