获取 trigger border 的时候失效，返回 NaN http://stackoverflow.com/questions/12226073/getting-css-border-value-with-jquery-in-firefox-14-0-1
获取 trigger border 的时候失效，返回 NaN
http://stackoverflow.com/questions/12226073/getting-css-border-value-with-jquery-in-firefox-14-0-1