Thanks a lot tuanphan. I tweaked and combined your two css codes to get just the littleBe page and pagination BG colour to change but the other portfolio pages to stay the same and ended up with this which seems to work -
body#item-5f47b82d8ee0877c453a2053 {
.section-background, .item-pagination[data-collection-type^="portfolio"], .page-section {
background: transparent !important;
}
& {
background-color: rgba(0,0,0,0) !important;
}}
only difference from your original code is I inserted the pagination bit into it