Display background color for the current active theme, if the active theme supports the customize background color ability in the Appearance Customize Screen.
This is a hexadecimal value for the color without the leading hash sign (#).
<?php background_color(); ?>
Display a div with the theme's background color:
<div id="background" style="background-color: #<?php background_color(); ?>"> Content here. </div>
background_color() is located in