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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.


                <div class="dad">
	<div class="son">


	width: 1000px;
	height: 1000px;
	margin:120px auto;
	position: fixed;
  width: 80px;
  height: 80px;
  background-color: blue;
  /*   left:0; */
/*  如果设置为0或其他具体数值,则会相对于视窗定位  */
/* 当left值设置为auto或left不设置(因left的属性值默认是auto),son位于父元素左上角,此时是否应该认为son是相对于父元素dad定位,那是不是就与position:fixed的定义相冲突了?而父元素并没有设置position:relative  */