<!doctype html><metacharset="utf-8"><title>CSS Overflow Test: ::scroll-button() activation with column scroll markers</title><linkrel="help"href="https://drafts.csswg.org/css-overflow-5/#scroll-buttons"><scriptsrc="/resources/testharness.js"></script><scriptsrc="/resources/testharnessreport.js"></script><scriptsrc="/resources/testdriver.js"></script><scriptsrc="/resources/testdriver-actions.js"></script><scriptsrc="/resources/testdriver-vendor.js"></script><style>*{margin:0;padding:0;}#scroller{width:600px;height:300px;overflow:auto;columns:1;gap:0;column-fill:auto;scroll-marker-group:after;white-space:nowrap;}#scrollerdiv{background:green;display:inline-block;width:600px;height:270px;}#scroller:first-child{background:purple;}#scroller::scroll-marker-group{border:3pxsolidblack;padding:5px;display:flex;height:20px;width:40px;}#scroller::scroll-button(right){content:">";background:blue;display:flex;height:20px;width:20px;top:0px;left:0px;position:absolute;z-index:99;}#scroller::column::scroll-marker{content:"";width:10px;height:10px;background-color:blue;border-radius:100%;display:inline-block;}</style><divid="scroller"><div></div><br><div></div></div><script>/* Double click as recommended scroll amount is 85% of the page, so to make sure all browsers reach the end. */promise_test(asynct=>{actions_promise=newtest_driver.Actions().pointerMove(5,5).pointerDown().pointerUp().pointerDown().pointerUp().send();awaitactions_promise;assert_equals(scroller.scrollLeft,600);});</script>