<!DOCTYPE html>
<html>
<style>
.container {
    font: 20px/1 Ahem, sans-serif;
    width: 500px;
    height: 200px;
    border: 1px solid black;
}

.rounded-rect {
    width: 320px;
    height: 160px;
    border: 1px solid blue;
    border-top-left-radius: 60px 40px;
    -webkit-shape-outside: inset(0px 0px 0px 0px round 60px 0 0 0 / 40px);
}
</style>

<body>
<div class="container" style="text-align: right">
X<br/>
    <div style="float: right" class="rounded-rect"></div>
X<br/>
X<br/>
X<br/>
X<br/>
X<br/>
X<br/>
X<br/>
X
</div>

<p>Requires Ahem font. There is a 0px size inset applied on the right float with 60px/40px top left radius.<br>
The black squares should trace the left side of the rounded rectangle's blue outline.</p>
<p>Bug <a href="http://webkit.org/b/125112">125112</a>: [CSS Shapes] Support inset for shape-outside</p>

</body>