Basic CSS Question – Selectively Overriding Site-wide styling

Hello, I’m very fresh to the world of CSS styling. I wanted to give most of the elements on my site rounded off corners on the top. Using the code below, I was able to accomplish this mostly to my liking.

.fl-builder-content *, .fl-builder-content *::before, .fl-builder-content *::after {
    border-radius: 15px 15px 0px 0px;
    box-sizing: border-box;
}

But as can be seen on http://consumidores.wpengine.com/, there are several instances where it would be ideal to override this rounded-upper corner styling (e.g. within the slider and the individual blog entries portions). My google-fu is failing me, can anybody offer any advice?

Thanks!