Visibility issues ? a worry for designers since manchester united players complained of being unable to see each other in a grey strip ? have been so successfully circumnavigated that it seems likely that chelsea could now practise at night without any need of floodlights 有关可见性的问题? ?这个问题曾因曼联球员抱怨灰色客场服让他们在场上彼此看不见而让设计师烦恼? ?是如此成功地被解决了，看上去切尔西如今甚至可以在没有灯光的晚间进行训练了。
