practice

<html>

.オレンジ_リレーティブ{position:relative;
top:100px;
left:200px;
height:100px;
width:100px;
background-color:orange;
z-index:10;}

.ブルー_アブソリュート{position:absolute;
top:100px;
left:200px;
height:100px;
width:100px;
background-color:dodgerblue;
border-radius:50%;}

.ボーダー_10_リレーティブ{position:relative;
top:300px;
left:20px;
height:100px;
width:100px;
border:10px solid black;}

.ボーダー_40_アブソリュート{height:100px;
position:absolute;
top:0;
left:0;
height:100px;
width:100px;
border:40px solid silver;}
</style>

</html>