style(runbackup): gray card via bg-body-secondary utility class
Move the card background off a custom CSS rule and onto a Bootstrap
utility class (bg-body-secondary) on the card element itself, so the gray
panel background is declared in the markup. Supersedes the .card
background-color rule added in the previous change.
Claude-Session: https://claude.ai/code/session_01WbGBN9VyRK61zczYWcCQ2i
@