By default, Safari Mobile does not use the :active state unless there is a touchstart event handler on the relevant element or on the .

    看来在iOS系统的移动设备中，需要在按钮元素或body/html上绑定一个touchstart事件才能激活:active状态。

    1. document.body.addEventListener('touchstart', function () { 
    2.   //...空函数即可
    3. });