chromium/third_party/blink/web_tests/fast/multicol/layers-in-multicol.html

<!DOCTYPE html>
<style>
    .multicol {
        -moz-column-width: 100px;
        -webkit-column-width: 100px;
        column-width: 100px;
        column-fill: auto;
        -webkit-column-gap: 0;
        -moz-column-gap: 0;
        column-gap: 0;
        height: 100px;
        line-height: 20px;
        border: 5px solid maroon;
        width: 300px;
    }
    .block {
        display: inline-block;
        width: 1em;
        height: 10px;
        background-color: green;
    }
    .opacity {
        opacity: 0.5;
        color: green;
    }
    .relative {
        position: relative;
        top: -4px;
        color: green;
    }
</style>
<p>
    Test layers which are fully contained within a single column.
</p>
LTR:
<div class="multicol">
    line1<br>
    line2<br>
    line3<br>
    line4<br>
    line5<br>
    line6<br>
    <div class="block"></div> line7<br>
    line8<br>
    <span class="relative">relative9</span><br>
    line10<br>
    line11<br>
    line12<br>
    <!-- The extra inner span below forces the creation of a transparency layer in Skia to work
         around optimizations that would cause blending differences between the test and the
         expectation. -->
    <span class="opacity">opacity<span>13</span></span><br>
    line14
</div>

RTL:
<div class="multicol" dir="rtl">
    line1<br>
    line2<br>
    line3<br>
    line4<br>
    line5<br>
    line6<br>
    <div class="block"></div> line7<br>
    line8<br>
    <span class="relative">relative9</span><br>
    line10<br>
    line11<br>
    line12<br>
    <!-- The extra inner span below forces the creation of a transparency layer in Skia to work
         around optimizations that would cause blending differences between the test and the
         expectation. -->
    <span class="opacity">opacity<span>13</span></span><br>
    line14
</div>