You might have been placing it at the guide but not the code itself, which happens if you did not use control + f in the code editor? ^^

Have you replaced the background hex colour under PROFILE (which is under PAGEDOLL)?

EDIT: just found it, please change the hexcode in <div class="card border-0 p-3 py-4" style="background:#f9f9f9;border-radius:15px;"> !!