我是指一个视频教程，设计师使用font：0/0 a;对于图像替换，所以我得到0是字体大小，另外0是线高，但设计师跳过一个部分只是说这是一个黑客。
那么那究竟在做什么呢？
解决方法
http://nicolasgallagher.com/another-css-image-replacement-technique/
font:0/0 a – a shorthand property that zeros out the font size and line-height. The a value acts as a very short font-family (an idea taken from the BEM implementation of this method). The CSS validator complains that using 0/0 in the shorthand font property is not valid,but every browser accepts it and this appears to be an error in the validator. Using font:0px/0 a passes validation but it displayed as font:0/0 a in the code that the validator flags as valid.
