Not sure exactly what you're trying to achieve, but several things I can say.
1. Always include a link to your site.
2. What template are you using? On what version of Joomla? The custom CSS methods are different for different versions of Joomla and different versions of the Gantry Framework.
3. The code you put there from your CSS file is commented out. Anything between /* and */ is ignored.
What you have:/* .rt-container.main-surround #rt-header {
background-color: white !important;
} */
What it should be:.rt-container.main-surround #rt-header {
background-color: white !important;
}
By commenting out the CSS, you are teeling the browser not to use anything that is commented out.