Need help to change font size of paragraph in the header

Hello, I was wondering if anyone can help me with the code.
In the custom CSS file I have following

body #header.sticky-header {background:#’ . $evolve_menu_back_color. ‘;
border-bottom-color:#’ . evolve_hexDarker( $evolve_menu_back_color ). ‘;

<a href="14149403442">Click Here To Call US 1-414-940-3442 > </a>

this text allows me to create a clickable link to call.
How can I change the font color, text location and size of the font?
It’s being displayed in the header right under the web site name in the right lower corner of the header
Thank you in advance for any feed back