fix: empty inline nodes should not prevent margin collapse

Author: LastLeaf

float-pigment-forest/tests/custom/css_margin.rs

@@ -81,6 +81,19 @@ fn margin_collapse_1() {
     )
 }
 
+#[test]
+fn margin_collapse_empty_inline_nodes() {
+    assert_xml!(
+        r#"
+        <div style="height: 800px;">
+          <div style="height: 100px; margin-bottom: 50px;"></div>
+          <div style="display: inline; height: 0;"></div>
+          <div style="margin-top: 40px;" expect_top="150"></div>
+        </div>
+    "#
+    )
+}
+
 #[test]
 fn margin_collapse_negative() {
     assert_xml!(

float-pigment-layout/src/algo/flow.rs

@@ -69,10 +69,12 @@ pub(crate) fn is_empty_block<L: LengthNum>(
     padding_border_main_axis: L,
     min_main_size: L,
     node_inner_main_size: L,
+    main_size: OptionNum<L>,
 ) -> bool {
     if !padding_border_main_axis.is_zero()
         || !min_main_size.is_zero()
         || !node_inner_main_size.is_zero()
+        || (main_size.is_some() && !main_size.val().unwrap().is_zero())
     {
         return false;
     }
@@ -800,6 +802,7 @@ impl<T: LayoutTreeNode> Flow<T> for LayoutUnit<T> {
             padding_border.main_axis_sum(axis_info.dir),
             min_max_limit.min_main_size(axis_info.dir),
             total_main_size,
+            request.size.main_size(axis_info.dir),
         ) {
             collapsed_margin.collapsed_through = true;
         }