contain-paint-scrollable-frame-1.html

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<!DOCTYPE HTML>

<html reftest-async-scroll>

<body>

  <div style="width:400px; height:200px; overflow:scroll;

              scrollbar-width: none;

              border:2px solid black; background: red;

              contain:paint;"

       reftest-displayport-x="0" reftest-displayport-y="0"

       reftest-displayport-w="800" reftest-displayport-h="2000"

       reftest-async-scroll-x="0" reftest-async-scroll-y="100">

    <!-- This element is what we're hoping will fill the scrollport

         when the reftest snapshot is taken: -->

    <div style="background: lime; margin-top: 100px; height: 600px"></div>

    <!-- This element is just to be sure the scrollframe's "contain:paint"

         styling is actually having an effect. "contain:paint" should make the

         scrollframe become a containing block for this fixed-pos element, and

         then this element will position itself off the bottom of the

         scrollframe and will be entirely clipped. If we fail to honor

         "contain:paint" for some reason, then this element will instead use

         the *viewport* as its containing block, and it'll show up in the

         reftest snapshot and cause the reftest to fail. -->

    <div style="position: fixed; top: 320px; width: 50px; height: 50px;

                background: purple;"></div>

  </div>

</body>

</html>