Keep min-height-contained floats at block start

crates/obscura-render/src/dom.rs

@@ -7958,7 +7958,11 @@ fn build_children_with_float_zone(
                 && has_in_flow_generated_pseudo(Some(after))
         })
     });
-    if parent_has_definite_height || parent_has_clearfix {
+    let parent_min_height = styles.get(&parent_id).and_then(|parent| match parent.min_height {
+        crate::Dimension::Px(value) => Some(value),
+        _ => None,
+    });
+    if parent_has_definite_height || parent_has_clearfix || parent_min_height.is_some() {
         let fills_axis = |value: f32| (value - 1.0).abs() < 0.001;
         let substantive: Vec<NodeId> = dom_children
             .iter()
@@ -7985,12 +7989,20 @@ fn build_children_with_float_zone(
                 matches!(style.height, crate::Dimension::Percent(value) if fills_axis(value))
                     && style.size_expressions[1].is_none()
             });
-            let float_has_definite_height = float_style.is_some_and(|style| {
-                matches!(style.height, crate::Dimension::Px(_)) && style.size_expressions[1].is_none()
-            }) || float_fills_height;
+            let float_pixel_height = float_style.and_then(|style| match style.height {
+                crate::Dimension::Px(value) if style.size_expressions[1].is_none() => Some(value),
+                _ => None,
+            });
+            let float_has_definite_height = float_pixel_height.is_some() || float_fills_height;
+            let height_is_already_contained = parent_has_definite_height
+                || parent_has_clearfix
+                || parent_min_height
+                    .zip(float_pixel_height)
+                    .is_some_and(|(minimum, height)| minimum + 0.001 >= height);
             let sole_full_width_float = substantive.len() == 1
                 && float_percent_width.is_some_and(fills_axis)
-                && float_has_definite_height;
+                && float_has_definite_height
+                && height_is_already_contained;
             let split_band_flow = if parent_has_definite_height
                 && substantive.len() == 2
                 && substantive[0] == float_dom

crates/obscura-render/tests/layout_test.rs

@@ -978,6 +978,39 @@ fn clearfix_contains_a_full_width_definite_height_float() {
     );
 }
 
+#[test]
+fn min_height_floor_keeps_a_full_width_float_at_block_start() {
+    let tree = parse_html(
+        r#"
+        <style>
+          html, body { margin: 0 }
+          #host { width: 100%; min-height: 600px }
+          #float { float: left; width: 100%; height: 600px }
+          #following { height: 20px }
+        </style>
+        <div id="host"><div id="float"></div></div>
+        <div id="following"></div>
+        "#,
+    );
+    let layout = layout_dom(&tree, (800.0, 700.0));
+    let rect = |id| layout.rects[&tree.get_element_by_id(id).unwrap()];
+    let host = rect("host");
+    let float = rect("float");
+    let following = rect("following");
+    assert!(
+        (host.width - 800.0).abs() < 0.01 && (host.height - 600.0).abs() < 0.01,
+        "host: {host:?}"
+    );
+    assert!(
+        (float.x - 0.0).abs() < 0.01
+            && (float.y - 0.0).abs() < 0.01
+            && (float.width - 800.0).abs() < 0.01
+            && (float.height - 600.0).abs() < 0.01,
+        "float: {float:?}"
+    );
+    assert!((following.y - 600.0).abs() < 0.01, "following: {following:?}");
+}
+
 #[test]
 fn percentage_float_and_inline_sibling_share_definite_height_band() {
     let tree = parse_html(