How reduce div background color opacity without effect to inside content or links

Hi,
I really Amazing.. I read many forums regarding how can reduce background DIV opacity without effect inside content or images... In all forums I find answer not possible, everyone saying some thing some things not working different browsers finaly top forums also saying not possible this thing but My requirement is need 100% this thing so I done experiment so successfully it is working

Just use like :   background : rgba(248, 248, 248, 0.7) !important ;
248 means it is white so white will transparent, if you need black background transparent use like
background : rgba(0, 0, 0, 0.7) !important ;