numix-blue-gtk-theme/gtk-3.0/scss/widgets/_grid.scss

/******************
 ! Grid and flowbox
*******************/

.list {
    background-color: shade($bg_color, 0.97);
    color: $fg_color;

    &-row {
        &, &.button {
            border: none;
            border-radius: 0;
            padding: $spacing;
            background-image: none;
            background-color: transparent;
            box-shadow: none;

            &:hover {
                background-image: none;
                background-color: shade($bg_color, 1.02);
            }

            &:selected {
                &, &:hover, &:focus {
                    background-image: none;
                    background-color: $selected_bg_color;
                    color: $selected_fg_color;
                }
            }
        }
    }
}

.grid-child {
    &, GtkFlowBox & {
        padding: $spacing;
        border-radius: $roundness;

        &:selected {
            @extend %selected;

            outline-offset: -2px;
        }
    }
}