问CSS改变身体背景-颜色按钮悬停？

EN

var button = document.getElementById('hover');
var body = document.body;

button.onmouseover = function() {
	body.className = 'hovered';
}

button.onmouseout = function() {
	body.className = '';
}

body {background: #000;}
body.hovered {background: #ff0;}

<button id="hover">button</button>

#button:hover ~ #background {
  background-color: red;
}

#background {
  position:absolute;
  background-color: blue;
  top: 0px;
  right: 0px;
  bottom: 0px;
  left: 0px;
  z-index: -1;
}

<button id="button">Button</button>
<div id="background"></div>