wp-content/themes/twentyfifteen/inc/custom-header.php:205Enqueues front-end CSS for the header background color.
function twentyfifteen_header_background_color_css() { $color_scheme = twentyfifteen_get_color_scheme(); $default_color = $color_scheme[1]; $header_background_color = get_theme_mod( 'header_background_color', $default_color ); // Don't do anything if the current color is the default. if ( $header_background_color === $default_color ) { return; } $css = ' /* Custom Header Background Color */ body:before, .site-header { background-color: %1$s; } @media screen and (min-width: 59.6875em) { .site-header, .secondary { background-color: transparent; } .widget button, .widget input[type="button"], .widget input[type="reset"], .widget input[type="submit"], .widget_calendar tbody a, .widget_calendar tbody a:hover, .widget_calendar tbody a:focus { color: %1$s; } } '; wp_add_inline_style( 'twentyfifteen-style', sprintf( $css, $header_background_color ) );}Introduced in Twenty Fifteen 1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-content/themes/twentyfifteen/inc/custom-header.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.