最近在做一个 flip 效果的时候发现一个奇怪的问题，设置了 backface-visiable：hidden；overflow：hidden 的元素反转180度以后背面没有被隐藏，最终还是被Google出来了，overflow会覆盖transform-style: preserve-3d属性，还有以下一些元素会导致transform-style: preserve-3d失效：
参考地址： http://codepen.io/thebabydino/details/rACbl
Don't set overflow: hidden on elements with 3D transformed children
By Ana Tudor
The 'back' face of the card has a rotateY(180deg) set on it. Both faces have backface-visibility: hidden set. Setting overflow: hidden on their parent (the card) causes the 3D transformed face ('back' face) to disappear and backface-visibility: hidden to be ignored for the other.
From the spec (link):
The following CSS property values require the user agent to create a flattened representation of the descendant elements before they can be applied, and therefore override the behavior of transform-style: preserve-3d:
overflow: any value other than visible.
filter: any value other than none.
clip: any value other than auto.
clip-path: any value other than none.
isolation: used value of isolate.
mask-image: any value other than none.
mask-box-source: any value other than none.
mix-blend-mode: any value other than normal.
The computed value of transform-style is not affected.
