好啦  我決定以後在這記筆記吧哈哈哈哈哈哈~~~~~~~~~重點程式碼為轉載~~

css:

  width: 100%;

  /* 重點*/
  background: #fff;
  background: -webkit-linear-gradient(rgba(255,255,255,0),rgba(255,255,255,1));
  background: -moz-linear-gradient(top,rgba(0,0,0,0) 0%,rgba(0,0,0,1) 100%);     
  /* FireFox */
  background: -o-linear-gradient(top,rgba(0,0,0,0) 0%,rgba(0,0,0,1) 100%);  
  /* Opear */
  background: -ms-linear-gradient(rgba(255,255,255,0),rgba(255,255,255,1)); 

  height: 400rpx;

效果圖：