[css-grid-1] Add tests for overflowing padding. (#21872)
diff --git a/css/css-grid/grid-model/grid-overflow-padding-001.html b/css/css-grid/grid-model/grid-overflow-padding-001.html
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+++ b/css/css-grid/grid-model/grid-overflow-padding-001.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Grid Layout Test: Grid padding 'overflowing' the grid container size</title>
+<link rel="author" title="Tab Atkins-Bittner" href="https://xanthir.com/contact">
+<link rel="author" title="Elika J Etemad" href="http://inkedblade.org/contact">
+<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 scrollbars are shown when end-edge padding overflows the grid container.">
+<link href="/css/support/grid.css" rel="stylesheet">
+<style>
+ .grid {
+ grid: 100px / 100px;
+ width: 100px;
+ height: 100px;
+ padding: 0 50px 50px 0;
+ }
+</style>
+<p>The test passes if you see a grey square below and both scrollbars are visible.</p>
+<div class="grid"></div>
diff --git a/css/css-grid/grid-model/grid-overflow-padding-002.html b/css/css-grid/grid-model/grid-overflow-padding-002.html
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+++ b/css/css-grid/grid-model/grid-overflow-padding-002.html
@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>CSS Grid Layout Test: Grid areas and padding 'overflowing' the grid container size</title>
+<link rel="author" title="Tab Atkins-Bittner" href="https://xanthir.com/contact">
+<link rel="author" title="Elika J Etemad" href="http://inkedblade.org/contact">
+<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 scrollbars are shown when a combination of padding and the grid overflows the grid container, and that the padding is not applied to abspos positioning.">
+<link href="/css/support/grid.css" rel="stylesheet">
+<style>
+ .grid {
+ grid: 120px / 120px;
+ width: 100px;
+ height: 100px;
+ padding: 10px 20px 20px 10px;
+ overflow: auto;
+ }
+ .abspos {
+ position: absolute;
+ width: 10px;
+ height: 10px;
+ top: 140px;
+ left: 140px;
+ }
+</style>
+<p>The test passes if you see a grey square below and both scrollbars are visible.</p>
+<div class="grid"><div class=abspos></div></div>
