css/css-grid/grid-model/grid-areas-overflowing-grid-container-001.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Grid Layout Test: Grid areas 'overflowing' the grid container size</title>
<link rel="author" title="Javier Fernandez" href="mailto:jfernandez@igalia.com">
<link rel="help" href="https://drafts.csswg.org/css-grid/#grid-model">
<link rel="help" href="https://drafts.csswg.org/css-overflow-3/#propdef-overflow">
<link rel="match" href="reference/100x100-grey-box-with-scrollbars.html">
<meta name="assert" content="This test verifies that the scrollbars are shown on an empty grid if there are grid areas which exceed the grid container size, since the grid itself can cause overflow.">
<link href="/css/support/grid.css" rel="stylesheet">
<style>
    .grid {
       grid: 150px / 150px;
       width: 100px;
       height: 100px;
       overflow: auto;
    }
</style>
<p>The test passes if you see a grey square below and both scrollbars are visible.</p>
<div class="grid"></div>