Define GeneratePress Customizer Colors
<?php
add_filter( 'generate_default_color_palettes', 'tu_custom_color_palettes' );
function tu_custom_color_palettes( $palettes ) {
$palettes = array(
'#111111',
'#222222',
'#333333',
'#444444',
'#555555',
'#666666',
'#777777',
'#888888',
);
return $palettes;
}