You have the following javascript error on your homepage:
Bootstrap's JavaScript requires jQuery version 1.9.1 or higher, but lower than version 4
This is caused by the plugin Carousel Horizontal Posts Content Slider plugin which is loading an old version of jQuery (version 1.8).
You’ll need to either replace that plugin, or contact the developer and ask them to avoid loading their own jQuery script, and just use the one bundled with WordPress.