code: function( el, props ) {
          var key, pkey;
          for ( key in props ) {
              if ( props.hasOwnProperty( key ) ) {
                  pkey = pfx( key );
                  if ( pkey !== null ) {
                      el.style[ pkey ] = props[ key ];
                  }
              }
          }
          return el;
      }
docs: `css` function applies the styles given in `props` object to the element given as `el`. It runs all property names through `pfx` function to make sure proper prefixed version of the property is used.