#anniu_index {
position:absolute;
width:200px;
height:200px;
padding-top:5px;
text-align:center;
display:block;
z-index:1;
right:5px;
top:5px;
cursor:pointer;
outline:none;
-webkit-tap-highlight-color: rgba(0,0,0,0);
}

最关键的一句：

-webkit-tap-highlight-color: rgba(0,0,0,0);