you have to adjust your CSS files in your site template or in your CB template located in
/templates/rt_nebulae_j16/css/
and in
/components/com_comprofiler/plugin/templates/default/template.css
ie: for your problem try something like this:
#rt-page-surround .inputbox:focus {
color: black;
}
Using CSS you can adjust colors and layout entirely. I recommend using Firebug to allow you to inspect the HTML and find what Classes and/or IDs to use in your CSS
More on CSS usage can be found at the following URL.
www.w3schools.com/css/default.asp