diff --git a/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-001.html b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-001.html
new file mode 100644
index 00000000000000..7683e485c05cae
--- /dev/null
+++ b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-001.html
@@ -0,0 +1,20 @@
+
+
+CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Absolute Positioned Descendant
+
+
+
+
+
+
+
+
+
+Test passes if there is a filled green square and no red.
+
+
diff --git a/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-002.html b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-002.html
new file mode 100644
index 00000000000000..1e7a754f74da30
--- /dev/null
+++ b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-002.html
@@ -0,0 +1,24 @@
+
+
+CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Absolute Positioned Descendant
+
+
+
+
+
+
+
+
+
+Test passes if there is a filled green square and no red.
+
+
diff --git a/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-003.html b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-003.html
new file mode 100644
index 00000000000000..be0305181914e9
--- /dev/null
+++ b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-003.html
@@ -0,0 +1,20 @@
+
+
+CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Absolute Positioned Descendant
+
+
+
+
+
+
+
+
+
+Test passes if there is a filled green square and no red.
+
+
diff --git a/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-004.html b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-004.html
new file mode 100644
index 00000000000000..61d50a10c10290
--- /dev/null
+++ b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-004.html
@@ -0,0 +1,20 @@
+
+
+CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Fixed Positioned Descendant
+
+
+
+
+
+
+
+
+
+Test passes if there is a filled green square and no red.
+
+
diff --git a/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-005.html b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-005.html
new file mode 100644
index 00000000000000..4473cb8d2ba4ea
--- /dev/null
+++ b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-005.html
@@ -0,0 +1,24 @@
+
+
+CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Fixed Positioned Descendant
+
+
+
+
+
+
+
+
+
+Test passes if there is a filled green square and no red.
+
+
diff --git a/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-006.html b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-006.html
new file mode 100644
index 00000000000000..79350eac516f28
--- /dev/null
+++ b/css/css-grid/grid-items/grid-items-relative-positioned-containing-block-006.html
@@ -0,0 +1,21 @@
+
+
+CSS Grid Layout Test: Relative Positioned Grid Items as a Containing Block of Absolute and Fixed Positioned Descendant
+
+
+
+
+
+
+
+
+
+Test passes if there is a filled green square and no red.
+
+
diff --git a/css/css-grid/grid-items/support/grid-items-relative-positioned-containing-block.css b/css/css-grid/grid-items/support/grid-items-relative-positioned-containing-block.css
new file mode 100644
index 00000000000000..ccdecf612d65a6
--- /dev/null
+++ b/css/css-grid/grid-items/support/grid-items-relative-positioned-containing-block.css
@@ -0,0 +1,32 @@
+.grid {
+ display: grid;
+ width: 100%;
+ grid-template-columns: 100px;
+ grid-template-rows: 100px;
+}
+.container {
+ position: relative;
+ grid-area: 1 / 1;
+}
+.box1 {
+ position: absolute;
+ width: 100px;
+ height: 100px;
+ grid-area: 1 / 1;
+}
+.box-abspos {
+ position: absolute;
+ width: 100%;
+ height: 100%;
+}
+.box-fixpos {
+ position: fixed;
+ width: 100px;
+ height: 100px;
+}
+.red {
+ background: red;
+}
+.green {
+ background: green;
+}