Remove OVERLAY/OPACITY effect on hover throughout my site

Hi!
I will like to remove the WHITE OVERLAY or OPACITY effect that I have throughout my site when hovering on images. This currently happens:

- https://www.lacalifornie.es FEATURED PRODUCTS towards the bottom
- https://www.lacalifornie.es/studio PORTFOLIO PAGE 
- https://www.lacalifornie.es/studio/arco PROJECT PAGE (I need to maintain the lightbox on click)
- https://www.lacalifornie.es/all PRODUCT LIST PAGE (I need to maintain the different image on hover)

Any idea on how to do this? thanks in advance.

Add this code to Website Tools (under Not Linked) > Custom CSS

/* remove on Studio page */
.portfolio-overlay {
    opacity: 0 !important;
    background-color: none !important;
}
a.grid-item {
    opacity: 1 !important;
}

(I see problem appears on /studio page only)