<!DOCTYPE HTML>
<style>
::-webkit-scrollbar {
    width: 12px;
    height: 12px;
}
::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3); 
    -webkit-border-radius: 10px;
    border-radius: 10px;
}
::-webkit-scrollbar-thumb {
    -webkit-border-radius: 10px;
    border-radius: 10px;
    background: rgba(255,150,250,0.8);
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.5); 
}
html {
    overflow: scroll;
}
body {
    width: 1000px;
    height: 1000px;
}
div {
    width: 100px;
    height: 100px;
    overflow: scroll;
}
</style>
<body>
<iframe src="resources/scrollable-iframe-customscrollbar-expected.html"></iframe>
<div><p style="width:200px;height:200px"></p></div>
<div><p style="width:200px;height:200px"></p></div>
</body>