@tuanphan
Thank you so much!! I needed to edit the drop down folder links color to black and I used your code as guidance.
So I'm guessing that putting: !important tells Squarespace to notice it.
/* Change dropdown menu background & link color :) */
.header-nav-folder-content {
background: #ffffff !important;
color: #000000 !important;
a {
color: #000000 !important;
}
}