Phone number change font colour and background colour

Hello

I want to add a temporary message on our website. The best place to do this would be at the top using the Phone number banner. However, I am finding it difficult to get the colours right because the colours are also used for the menu. I originally changed Alternative Background Colour to #ff3300 and Logo Area secondary font colour to #ffffff. This was great, but it also changed my main menu items. Then I tried the following quick CSS:

div.phone-info {
width: 100%;
text-align: center;
background-color: #ff3300;
color: #ffffff;
}

This kind of works. However, the font colour is still grey not white. And also, the orange banner does not go all the way across. Can you please advise me on the correct CSS to fix this?

Or if there is a better way of putting a banner across the top?

Many thanks

Andy