By default, the platform does not have this option. You can use the following CSS code.

Please follow the steps below:

    1. Go to BuddyBoss - Theme Options

    2. Under Custom Codes, enable CSS

    3. Append the following:

.bb-modal-overlay {
    background-color:  rgba(0, 0, 0, 0.8);
}

    4. Save changes.

Note: Any modifications are considered as custom work already. Know more about our Support policy here: https://www.buddyboss.com/support-policy/

Screenshots

Without Code

With Code: