WordPress body class browser and OS detection

functions.php

/**
 * Browser and OS detection
 * @link  http://www.wpbeginner.com/wp-themes/how-to-add-user-browser-and-os-classes-in-wordpress-body-class/
 */

function dxms_browser_os_body_class( $classes ) {
    global $is_lynx, $is_gecko, $is_IE, $is_opera, $is_NS4, $is_safari, $is_chrome, $is_iphone;

    if( $is_lynx ) $classes[] = 'lynx';
    elseif( $is_gecko ) $classes[] = 'gecko';
    elseif( $is_opera ) $classes[] = 'opera';
    elseif( $is_NS4 ) $classes[] = 'ns4';
    elseif( $is_safari ) $classes[] = 'safari';
    elseif( $is_chrome ) $classes[] = 'chrome';
    elseif( $is_IE ) {
        $classes[] = 'ie';
        if( preg_match( '/MSIE ([0-9]+)([a-zA-Z0-9.]+)/', $_SERVER['HTTP_USER_AGENT'], $browser_version ) ) {
            $classes[] = 'ie' . $browser_version[1];
        }

    } else $classes[] = 'unknown';

    if( $is_iphone ) {
        $classes[] = 'iphone';
    }

    if ( stristr( $_SERVER['HTTP_USER_AGENT'], 'mac' ) ) {
        $classes[] = 'osx';
    } elseif ( stristr( $_SERVER['HTTP_USER_AGENT'], 'linux' ) ) {
        $classes[] = 'linux';
    } elseif ( stristr( $_SERVER['HTTP_USER_AGENT'], 'windows' ) ) {
        $classes[] = 'windows';
    }
    
    return $classes;
}
add_filter( 'body_class', 'dxms_browser_os_body_class' );