diff --git a/components/layout/block.rs b/components/layout/block.rs
index d1a333f2b83..c703542b5f9 100644
--- a/components/layout/block.rs
+++ b/components/layout/block.rs
@@ -1058,10 +1058,17 @@ impl BlockFlow {
};
let float_info: FloatedBlockInfo = (**self.float.as_ref().unwrap()).clone();
+
+ // Our `position` field accounts for positive margins, but not negative margins. (See
+ // calculation of `extra_inline_size_from_margin` below.) Negative margins must be taken
+ // into account for float placement, however. So we add them in here.
+ let inline_size_for_float_placement = self.base.position.size.inline +
+ min(Au(0), self.fragment.margin.inline_start_end());
+
let info = PlacementInfo {
size: LogicalSize::new(
self.fragment.style.writing_mode,
- self.base.position.size.inline,
+ inline_size_for_float_placement,
block_size + self.fragment.margin.block_start_end())
.convert(self.fragment.style.writing_mode, self.base.floats.writing_mode),
ceiling: clearance + float_info.float_ceiling,
@@ -2214,9 +2221,9 @@ pub trait ISizeAndMarginsComputer {
container_size - inline_size - fragment.margin.inline_end
};
- // To calculate the total size of this block, we also need to account for any additional
- // size contribution from positive margins. Negative margins means the block isn't made
- // larger at all by the margin.
+ // To calculate the total size of this block, we also need to account for any
+ // additional size contribution from positive margins. Negative margins means the block
+ // isn't made larger at all by the margin.
extra_inline_size_from_margin = max(Au(0), fragment.margin.inline_start) +
max(Au(0), fragment.margin.inline_end);
}
diff --git a/tests/ref/basic.list b/tests/ref/basic.list
index 1318c9d6f4d..f050d04fed0 100644
--- a/tests/ref/basic.list
+++ b/tests/ref/basic.list
@@ -99,6 +99,7 @@ flaky_cpu == append_style_a.html append_style_b.html
== float_under_top_margin_a.html float_under_top_margin_ref.html
== floated_generated_content_a.html floated_generated_content_b.html
== floated_list_item_a.html floated_list_item_ref.html
+== floated_negative_margins_a.html floated_negative_margins_ref.html
== floated_table_with_margin_a.html floated_table_with_margin_ref.html
== focus_selector.html focus_selector_ref.html
== font_advance.html font_advance_ref.html
diff --git a/tests/ref/floated_negative_margins_a.html b/tests/ref/floated_negative_margins_a.html
new file mode 100644
index 00000000000..49e3e9b5d6b
--- /dev/null
+++ b/tests/ref/floated_negative_margins_a.html
@@ -0,0 +1,16 @@
+
+
+Hello
+
diff --git a/tests/ref/floated_negative_margins_ref.html b/tests/ref/floated_negative_margins_ref.html
new file mode 100644
index 00000000000..6fc5d275c6b
--- /dev/null
+++ b/tests/ref/floated_negative_margins_ref.html
@@ -0,0 +1,15 @@
+
+
+Hello
+