While the css function correctly handles a single property or height that is passed with a negative value it does not handle multiple key/value pairs.

Existing code:

css: function( key, value ) {
		// ignore negative width and height values
		if ( (key == 'width' || key == 'height') && parseFloat(value) < 0 )
			value = undefined;
		return this.attr( key, value, "curCSS" );
	}
Suggested change:
css: function( key, value ) {
		// ignore negative width and height values
		if ( (key == 'width' || key == 'height') && parseFloat(value) < 0 )
			value = undefined;
                if(typeof(key.height)!==undefined && parseFloat(key.height) < 0)key.height = undefined;
                if(typeof(key.width)!==undefined && parseFloat(key.width) < 0)key.width = undefined;
		return this.attr( key, value, "curCSS" );
	}