Jacket for wedding

[pommedechocolat]

www.net-a-porter.com/product/187752

I am wearing this in navy with flats and a silver cardie (normal length - not long or shrunken) to a wedding next weekend. Not a thick cardie. just seen weather forecast and will need a jacket too. Don't want to spend too much and have no idea what would go with it... Any ideas anyone?

I'm thinking a shorter blazer would be shorter than the cardie, a longer blazer would look wrong and a trench/mac thing would be a funny length against the skirt! Anyone know any other types of jacket?!