Hi There,
I see that the CSS on your site is heavily minified. Please clear all your caching plugins and your minifier plugins.
Then check your entire CSS on child theme’s style.css file for error, and address it. You can check that here.
If you plan to place your custom CSS on style.css file, make sure you make its selector one step more specific.
For example, the css code provided by Lely above might not able to overwrite the default border if you added it on the style.css file. So you need that code to be more specific, you can add a parent div class to it.
.x-site .x-slider-container.below {
border-bottom: none;
}
Please read this post for more details.
Thanks,