減少圖片能減少HTTP請求,同時減少頁面大小,更容易維護,常用的屬性如下: * linear and radial gradients * border-radius * box-shadow * rgba * transform * css mask 常見的使用場景有:?[polished buttons via gradients](http://cubiq.org/dropbox/cssgrad.html),?[replicate many other effects](http://www.phpied.com/css-performance-ui-with-fewer-images/)