// Allow SVG without plugin
add_filter( 'wp_check_filetype_and_ext', function($data, $file, $filename, $mimes) {

  global $wp_version;
  if ( $wp_version !== '4.7.1' ) {
     return $data;
  }

  $filetype = wp_check_filetype( $filename, $mimes );

  return [
      'ext'             => $filetype['ext'],
      'type'            => $filetype['type'],
      'proper_filename' => $data['proper_filename']
  ];

}, 10, 4 );

if ( ! function_exists( 'ns_cc_mime_types' ) ) {
	function jc_cc_mime_types( $mimes ){
	  $mimes['svg'] = 'image/svg+xml';
	  return $mimes;
	}
	add_filter( 'upload_mimes', 'ns_cc_mime_types' );
}

if ( ! function_exists( 'ns_fix_svg' ) ) {
	function ns_fix_svg() {
	  echo '<style type="text/css">
			.attachment-266x266, .thumbnail img {
				 width: 100% !important;
				 height: auto !important;
			}
			</style>';
	}
	add_action( 'admin_head', 'jc_fix_svg' );
}