Is there a way to reduce the size of this image in the CSS class 'illustration'? i.e. 50% smaller. The size of the illustration comes from the class, but is it possible to make the picture smaller within the size from the class or should you just use another class?

<img class='illustration' alt='UK editions' src='/uploads/newbb/10_622235f0ce7c9.jpg'/> [i]£2.10 with text at higher position on spine [3][/i][clear]

UK editions £2.10 with text at higher position on spine [3]