Changing header media url text box bubble color and menu color

Hi, I am interested in changing the header media url text box bubble color and menu color from the default green. Can someone point me towards the right CSS code to change this color? I added this code to the additional CSS and it did not work. (CSS below is for the header box I don't have a clue on how to change menu) Go to => Appearance => Customize => Additional CSS and add the following CSS Code. .readmore.button { background-color: #123456 !important; } Please advise. Thanks, GsPop