1<html><head>
2<meta name="viewport" content="width=device-width">
3<style>
4.d1 {position:fixed; top:5; right:5; z-index:2; overflow:hidden;}
5.o {background:green; height:40px; width:200px;}
6.t { width:2000px; height:198px; background-color: lightgray; border: 1px solid blue;}
7body { margin: 0px; }
8</style>
9<script>
10
11var fixed;
12
13function remove_child()
14{
15  fixed = document.getElementById("d1");
16  fixed.parentElement.removeChild(fixed);
17}
18
19function add_child()
20{
21  document.body.appendChild(fixed);
22}
23
24</script>
25</head>
26<body>
27<div class="d1" id="d1"><div class="o">This is a test</div></div>
28<div class="t">
29000
30</div>
31<div class="t">
32200<br>
33<button onclick="remove_child();">remove fixed</button>
34</div>
35<div class="t">
36400<br>
37<button onclick="add_child();">add fixed</button>
38</div>
39<div class="t">
40600<br>
41</div>
42<div class="t">
43800
44</div>
45<div class="t">
461000
47</div>
48<div class="t">
491200
50</div>
51<div class="t">
521400
53</div>
54<div class="t">
551600
56</div>
57<div class="t">
581800
59</div>
60<div class="t">
612000
62</div>
63<div class="t">
642200
65</div>
66<div class="t">
672400
68</div>
69<div class="t">
702600
71</div>
72<div class="t">
732800
74</div>
75<div class="t">
763000
77</div>
78<div class="t">
793200
80</div>
81<div class="t">
823400
83</div>
84<div class="t">
853600
86</div>
87<div class="t">
883800
89</div>
90<div class="t">
914000
92</div>
93</body></html>
94