I did a test with the {fmt} and was super easy to change background color, but I can't get the same with spdlog.
I can get the same result with spdlog, but is a weird code
fmt::print( bg( fmt::terminal_color::yellow ) | fg( fmt::terminal_color::black ), " {1:<{0}}\n", 120, "message" );
spdlog::set_pattern( "%v" );
spdlog::info( "\033[43m\033[30m {1:<{0}} \033[m", 120, "message" );