是的，这是可能的。采取行动look at the codex 您将看到，您可以通过add_theme_support( \'custom-background\'). 其中一个是回调函数，它生成<style> 标签：_custom_background_cb. 您可以将自己的函数作为参数传递给add_theme_support.

这是code of the original function （从WP 4.5中检索，请检查是否稍后阅读）：

function _custom_background_cb() {
    // $background is the saved custom image, or the default image.
    $background = set_url_scheme( get_background_image() );

    // $color is the saved custom color.
    // A default has to be specified in style.css. It will not be printed here.
    $color = get_background_color();

    if ( $color === get_theme_support( \'custom-background\', \'default-color\' ) ) {
        $color = false;
    }

    if ( ! $background && ! $color )
        return;

    $style = $color ? "background-color: #$color;" : \'\';

    if ( $background ) {
        $image = " background-image: url(\'$background\');";

        $repeat = get_theme_mod( \'background_repeat\', get_theme_support( \'custom-background\', \'default-repeat\' ) );
        if ( ! in_array( $repeat, array( \'no-repeat\', \'repeat-x\', \'repeat-y\', \'repeat\' ) ) )
            $repeat = \'repeat\';
        $repeat = " background-repeat: $repeat;";

        $position = get_theme_mod( \'background_position_x\', get_theme_support( \'custom-background\', \'default-position-x\' ) );
        if ( ! in_array( $position, array( \'center\', \'right\', \'left\' ) ) )
            $position = \'left\';
        $position = " background-position: top $position;";

        $attachment = get_theme_mod( \'background_attachment\', get_theme_support( \'custom-background\', \'default-attachment\' ) );
        if ( ! in_array( $attachment, array( \'fixed\', \'scroll\' ) ) )
            $attachment = \'scroll\';
        $attachment = " background-attachment: $attachment;";

        $style .= $image . $repeat . $position . $attachment;
    }
?>
<style type="text/css" id="custom-background-css">
body.custom-background { <?php echo trim( $style ); ?> }
</style>
<?php
}

$defaults = array(
    \'default-color\'          => \'\',
    \'default-image\'          => \'\',
    \'default-repeat\'         => \'\',
    \'default-position-x\'     => \'\',
    \'default-attachment\'     => \'\',
    \'wp-head-callback\'       => \'wpse228339_callback_function\',
    \'admin-head-callback\'    => \'\',
    \'admin-preview-callback\' => \'\'
);
add_theme_support( \'custom-background\', $defaults );