diff --git a/Tests/LibWeb/Layout/expected/child-of-abspos-percentage-height.txt b/Tests/LibWeb/Layout/expected/child-of-abspos-percentage-height.txt
new file mode 100644
index 00000000000000..bf318c75bf6cf8
--- /dev/null
+++ b/Tests/LibWeb/Layout/expected/child-of-abspos-percentage-height.txt
@@ -0,0 +1,13 @@
+Viewport <#document> at (0,0) content-size 800x600 children: not-inline
+ BlockContainer at (0,0) content-size 800x0 [BFC] children: not-inline
+ BlockContainer
at (8,8) content-size 36.84375x17 positioned [BFC] children: not-inline
+ BlockContainer at (8,8) content-size 36.84375x17 children: inline
+ frag 0 from TextNode start: 0, length: 5, rect: [8,8 36.84375x17] baseline: 13.296875
+ "hello"
+ TextNode <#text>
+
+ViewportPaintable (Viewport<#document>) [0,0 800x600]
+ PaintableWithLines (BlockContainer) [0,0 800x0]
+ PaintableWithLines (BlockContainer) [8,8 36.84375x17]
+ PaintableWithLines (BlockContainer
) [8,8 36.84375x17]
+ TextPaintable (TextNode<#text>)
diff --git a/Tests/LibWeb/Layout/input/child-of-abspos-percentage-height.html b/Tests/LibWeb/Layout/input/child-of-abspos-percentage-height.html
new file mode 100644
index 00000000000000..e218abaa9561e1
--- /dev/null
+++ b/Tests/LibWeb/Layout/input/child-of-abspos-percentage-height.html
@@ -0,0 +1,5 @@
+
hello
diff --git a/Userland/Libraries/LibWeb/Layout/FormattingContext.cpp b/Userland/Libraries/LibWeb/Layout/FormattingContext.cpp
index 6ca942b9345447..7b2e48417c668e 100644
--- a/Userland/Libraries/LibWeb/Layout/FormattingContext.cpp
+++ b/Userland/Libraries/LibWeb/Layout/FormattingContext.cpp
@@ -1255,10 +1255,15 @@ void FormattingContext::layout_absolutely_positioned_element(Box const& box, Ava
// If the box width and/or height is fixed and/or or resolved from inset properties,
// mark the size as being definite (since layout was not required to resolve it, per CSS-SIZING-3).
- if (box.computed_values().inset().left().is_length() && box.computed_values().inset().right().is_length()) {
+ auto is_length_but_not_auto = [](auto& length_percentage) {
+ return length_percentage.is_length() && !length_percentage.is_auto();
+ };
+ if (is_length_but_not_auto(box.computed_values().inset().left())
+ && is_length_but_not_auto(box.computed_values().inset().right())) {
box_state.set_has_definite_width(true);
}
- if (box.computed_values().inset().top().is_length() && box.computed_values().inset().bottom().is_length()) {
+ if (is_length_but_not_auto(box.computed_values().inset().top())
+ && is_length_but_not_auto(box.computed_values().inset().bottom())) {
box_state.set_has_definite_height(true);
}