谁能解释一下,为什么使用 relative是设置right,bottom 后,看不到div 呀,哪里多出来的 top , left 属性负值呀?

chrome 中修改后,

同样,设置 left,top 后, 多出来 right/bottom 的负值属性?

源码:
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>CSS 定位:relative &&  absolute</title>
    <style>        
        .relative{            
            background-color: #0f0;
            width: 100px;
            height: 100px;
            position: relative;            
           right: 200px;
            bottom: 200px;
        }        
    </style>
</head>
<body>
    <div>
        <div>
            <!--  -->
        </div>
    </div>
</body>
</html><!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>CSS 定位:relative &&  absolute</title>
    <style>        
        .relative{            
            background-color: #0f0;
            width: 100px;
            height: 100px;
            position: relative;            
           left: 200px;
           top: 200px;
        }        
    </style>
</head>
<body>
    <div>
        <div>
            <!--  -->
        </div>
    </div>
</body>
</html> UFO2015
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