diff --git a/packages/core/src/compute_coords_from_placement.rs b/packages/core/src/compute_coords_from_placement.rs
index 0fec589..5525a93 100644
--- a/packages/core/src/compute_coords_from_placement.rs
+++ b/packages/core/src/compute_coords_from_placement.rs
@@ -42,18 +42,18 @@ pub fn compute_coords_from_placement(
     };
 
     let rtl = rtl.unwrap_or(false);
-    match get_alignment(placement) {
-        Some(Alignment::Start) => {
-            coords.update_axis(alignment_axis, |value| {
-                value - common_align * (if rtl && is_vertical { -1.0 } else { 1.0 })
-            });
-        }
-        Some(Alignment::End) => {
-            coords.update_axis(alignment_axis, |value| {
-                value + common_align * (if rtl && is_vertical { -1.0 } else { 1.0 })
-            });
-        }
-        None => {}
+
+    if let Some(alignment) = get_alignment(placement) {
+        coords.update_axis(alignment_axis, |value| {
+            value
+                - common_align
+                    * (if alignment == Alignment::End {
+                        1.0
+                    } else {
+                        -1.0
+                    })
+                    * (if rtl && is_vertical { -1.0 } else { 1.0 })
+        });
     }
 
     coords
diff --git a/packages/core/src/middleware/auto_placement.rs b/packages/core/src/middleware/auto_placement.rs
index 102de9c..c7da6e4 100644
--- a/packages/core/src/middleware/auto_placement.rs
+++ b/packages/core/src/middleware/auto_placement.rs
@@ -236,23 +236,12 @@ impl<Element: Clone + PartialEq, Window: Clone + PartialEq> Middleware<Element,
             allowed_placements
         };
 
-        let overflow = platform.detect_overflow(
-            MiddlewareState {
-                elements: elements.clone(),
-                ..state
-            },
-            options.detect_overflow.unwrap_or_default(),
-        );
-
         let current_index = data.index;
         let current_placement = placements.get(current_index);
 
         if let Some(current_placement) = current_placement {
             let current_placement = *current_placement;
 
-            let alignment_sides =
-                get_alignment_sides(current_placement, rects, platform.is_rtl(elements.floating));
-
             // Make `compute_coords` start from the right place.
             if placement != current_placement {
                 return MiddlewareReturn {
@@ -266,6 +255,17 @@ impl<Element: Clone + PartialEq, Window: Clone + PartialEq> Middleware<Element,
                 };
             }
 
+            let overflow = platform.detect_overflow(
+                MiddlewareState {
+                    elements: elements.clone(),
+                    ..state
+                },
+                options.detect_overflow.unwrap_or_default(),
+            );
+
+            let alignment_sides =
+                get_alignment_sides(current_placement, rects, platform.is_rtl(elements.floating));
+
             let current_overflows = vec![
                 overflow.side(get_side(current_placement)),
                 overflow.side(alignment_sides.0),
diff --git a/packages/core/src/middleware/inline.rs b/packages/core/src/middleware/inline.rs
index 3d70cac..1cfc111 100644
--- a/packages/core/src/middleware/inline.rs
+++ b/packages/core/src/middleware/inline.rs
@@ -180,6 +180,18 @@ impl<Element: Clone + PartialEq + 'static, Window: Clone + PartialEq + 'static>
             .get_client_rects(elements.reference)
             .unwrap_or(vec![]);
 
+        // No rects (e.g. a hidden or detached reference, or a collapsed range) -
+        // keep the existing reference rect rather than resetting to an invalid
+        // one with non-finite values.
+        if native_client_rects.is_empty() {
+            return MiddlewareReturn {
+                x: None,
+                y: None,
+                data: None,
+                reset: None,
+            };
+        }
+
         let client_rects = get_rects_by_line(native_client_rects.clone());
         let fallback = rect_to_client_rect(get_bounding_rect(native_client_rects));
         let padding_object = get_padding_object(padding);
@@ -187,7 +199,8 @@ impl<Element: Clone + PartialEq + 'static, Window: Clone + PartialEq + 'static>
         let get_bounding_client_rect = move || {
             // There are two rects and they are disjoined.
             if client_rects.len() == 2
-                && client_rects[0].left > client_rects[1].right
+                && (client_rects[0].left > client_rects[1].right
+                    || client_rects[1].left > client_rects[0].right)
                 && let Some(x) = options.x
                 && let Some(y) = options.y
             {
@@ -222,19 +235,13 @@ impl<Element: Clone + PartialEq + 'static, Window: Clone + PartialEq + 'static>
                     } else {
                         last_rect.right
                     };
-                    let width = right - left;
-                    let height = bottom - top;
 
-                    return ClientRectObject {
+                    return rect_to_client_rect(Rect {
                         x: left,
                         y: top,
-                        width,
-                        height,
-                        top,
-                        right,
-                        bottom,
-                        left,
-                    };
+                        width: right - left,
+                        height: bottom - top,
+                    });
                 }
 
                 let is_left_side = placement.side() == Side::Left;
@@ -261,21 +268,13 @@ impl<Element: Clone + PartialEq + 'static, Window: Clone + PartialEq + 'static>
 
                 let top = measure_rects.first().expect("Enough elements exist.").top;
                 let bottom = measure_rects.last().expect("Enough elements exist.").bottom;
-                let left = min_left;
-                let right = max_right;
-                let width = right - left;
-                let height = bottom - top;
 
-                return ClientRectObject {
-                    x: left,
+                return rect_to_client_rect(Rect {
+                    x: min_left,
                     y: top,
-                    width,
-                    height,
-                    top,
-                    right,
-                    bottom,
-                    left,
-                };
+                    width: max_right - min_left,
+                    height: bottom - top,
+                });
             }
 
             fallback.clone()
diff --git a/packages/core/src/middleware/shift.rs b/packages/core/src/middleware/shift.rs
index 370a215..410c235 100644
--- a/packages/core/src/middleware/shift.rs
+++ b/packages/core/src/middleware/shift.rs
@@ -192,34 +192,30 @@ impl<Element: Clone + PartialEq + 'static, Window: Clone + PartialEq + 'static>
         let mut main_axis_coord = coords.axis(main_axis);
         let mut cross_axis_coord = coords.axis(cross_axis);
 
-        if check_main_axis {
-            let min_side = match main_axis {
-                Axis::X => Side::Left,
-                Axis::Y => Side::Top,
-            };
-            let max_side = match main_axis {
-                Axis::X => Side::Right,
-                Axis::Y => Side::Bottom,
-            };
-            let min = main_axis_coord + overflow.side(min_side);
-            let max = main_axis_coord - overflow.side(max_side);
+        let clamp_coord = |axis: Axis, coord: f64| -> f64 {
+            clamp(
+                coord
+                    + overflow.side(if axis == Axis::Y {
+                        Side::Top
+                    } else {
+                        Side::Left
+                    }),
+                coord,
+                coord
+                    - overflow.side(if axis == Axis::Y {
+                        Side::Bottom
+                    } else {
+                        Side::Right
+                    }),
+            )
+        };
 
-            main_axis_coord = clamp(min, main_axis_coord, max);
+        if check_main_axis {
+            main_axis_coord = clamp_coord(main_axis, main_axis_coord);
         }
 
         if check_cross_axis {
-            let min_side = match cross_axis {
-                Axis::X => Side::Left,
-                Axis::Y => Side::Top,
-            };
-            let max_side = match cross_axis {
-                Axis::X => Side::Right,
-                Axis::Y => Side::Bottom,
-            };
-            let min = cross_axis_coord + overflow.side(min_side);
-            let max = cross_axis_coord - overflow.side(max_side);
-
-            cross_axis_coord = clamp(min, cross_axis_coord, max);
+            cross_axis_coord = clamp_coord(cross_axis, cross_axis_coord);
         }
 
         let limited_coords = limiter.compute(MiddlewareState {
diff --git a/packages/core/src/middleware/size.rs b/packages/core/src/middleware/size.rs
index 634c362..e4a9d8f 100644
--- a/packages/core/src/middleware/size.rs
+++ b/packages/core/src/middleware/size.rs
@@ -207,27 +207,10 @@ impl<Element: Clone + PartialEq, Window: Clone + PartialEq> Middleware<Element,
         }
 
         if no_shift && alignment.is_none() {
-            let x_min = overflow.left.max(0.0);
-            let x_max = overflow.right.max(0.0);
-            let y_min = overflow.top.max(0.0);
-            let y_max = overflow.bottom.max(0.0);
-
             if is_y_axis {
-                available_width = width
-                    - 2.0
-                        * (if x_min != 0.0 || x_max != 0.0 {
-                            x_min + x_max
-                        } else {
-                            overflow.left.max(overflow.right)
-                        });
+                available_width = width - 2.0 * overflow.left.max(overflow.right);
             } else {
-                available_height = height
-                    - 2.0
-                        * (if y_min != 0.0 || y_max != 0.0 {
-                            y_min + y_max
-                        } else {
-                            overflow.top.max(overflow.bottom)
-                        });
+                available_height = height - 2.0 * overflow.top.max(overflow.bottom);
             }
         }
 
diff --git a/packages/core/src/types.rs b/packages/core/src/types.rs
index 229fac8..2294ffa 100644
--- a/packages/core/src/types.rs
+++ b/packages/core/src/types.rs
@@ -353,6 +353,7 @@ pub enum Boundary<Element> {
 #[derive(Clone, Debug, PartialEq)]
 pub enum RootBoundary {
     Viewport,
+    LayoutViewport,
     Document,
     Rect(Rect),
 }
diff --git a/packages/dom/src/platform/get_clipping_rect.rs b/packages/dom/src/platform/get_clipping_rect.rs
index ce8f396..fafd89a 100644
--- a/packages/dom/src/platform/get_clipping_rect.rs
+++ b/packages/dom/src/platform/get_clipping_rect.rs
@@ -4,7 +4,7 @@ use floating_ui_utils::{
     dom::{
         OverflowAncestor, get_computed_style, get_document_element, get_node_name,
         get_overflow_ancestors, get_parent_node, is_containing_block, is_last_traversable_node,
-        is_overflow_element, is_top_layer,
+        is_top_layer,
     },
     rect_to_client_rect,
 };
@@ -49,7 +49,8 @@ fn get_client_rect_from_clipping_ancestor(
         ElementOrRootBoundary::Element(element) => {
             get_inner_bounding_client_rect(&element, strategy)
         }
-        ElementOrRootBoundary::RootBoundary(RootBoundary::Viewport) => {
+        ElementOrRootBoundary::RootBoundary(RootBoundary::Viewport)
+        | ElementOrRootBoundary::RootBoundary(RootBoundary::LayoutViewport) => {
             get_viewport_rect(&get_document_element(Some(element.into())), strategy)
         }
         ElementOrRootBoundary::RootBoundary(RootBoundary::Document) => {
@@ -69,23 +70,6 @@ fn get_client_rect_from_clipping_ancestor(
     rect_to_client_rect(rect)
 }
 
-fn has_fixed_position_ancestor(element: &Element, stop_node: &Node) -> bool {
-    let parent_node = get_parent_node(element);
-    if &parent_node == stop_node
-        || !parent_node.is_instance_of::<Element>()
-        || is_last_traversable_node(&parent_node)
-    {
-        false
-    } else {
-        let element = parent_node.unchecked_into::<Element>();
-        get_computed_style(&element)
-            .get_property_value("position")
-            .expect("Computed style should have position.")
-            == "fixed"
-            || has_fixed_position_ancestor(&element, stop_node)
-    }
-}
-
 fn get_clipping_element_ancestors(element: &Element) -> Vec<Element> {
     // TODO: cache
 
@@ -99,7 +83,7 @@ fn get_clipping_element_ancestors(element: &Element) -> Vec<Element> {
             OverflowAncestor::VisualViewport(_) => None,
         })
         .collect();
-    let mut current_containing_block_computed_style: Option<CssStyleDeclaration> = None;
+    let mut last_kept_computed_style: Option<CssStyleDeclaration> = None;
     let element_is_fixed = get_computed_style(element)
         .get_property_value("position")
         .expect("Computed style should have position.")
@@ -116,37 +100,34 @@ fn get_clipping_element_ancestors(element: &Element) -> Vec<Element> {
         let computed_style = get_computed_style(current_element);
         let current_node_is_containing = is_containing_block(current_element.into());
 
-        let position = computed_style
-            .get_property_value("position")
-            .expect("Computed style should have position");
-
-        if !current_node_is_containing && position == "fixed" {
-            current_containing_block_computed_style = None;
-        }
-
-        let should_drop_current_node = if element_is_fixed {
-            !current_node_is_containing && current_containing_block_computed_style.is_none()
-        } else {
-            (!current_node_is_containing
-                && position == "static"
-                && current_containing_block_computed_style
-                    .as_ref()
-                    .is_some_and(|style| {
-                        let positon = style
-                            .get_property_value("position")
-                            .expect("Computed style should have position");
-
-                        positon == "absolute" || positon == "fixed"
-                    }))
-                || (is_overflow_element(current_element)
-                    && !current_node_is_containing
-                    && has_fixed_position_ancestor(element, current_element))
-        };
+        // Position of the containing block chain below the current node. A fixed
+        // element whose containing block hasn't been found yet is a fixed chain.
+        let last_position =
+            if let Some(last_kept_computed_style) = last_kept_computed_style.as_ref() {
+                last_kept_computed_style
+                    .get_property_value("position")
+                    .expect("Computed style should have position")
+            } else {
+                if element_is_fixed { "fixed" } else { "" }.to_owned()
+            };
+
+        // A non-containing ancestor does not clip the element when the chain
+        // below it escapes it: a fixed chain escapes all ancestors up to the
+        // next containing block, an absolute chain escapes static ancestors.
+        let should_drop_current_node = !current_node_is_containing
+            && (last_position == "fixed"
+                || (last_position == "absolute"
+                    && computed_style
+                        .get_property_value("position")
+                        .expect("Computed style should have position")
+                        == "static"));
 
         if should_drop_current_node {
+            // Drop non-containing blocks.
             result.retain(|ancestor| ancestor != current_element);
         } else {
-            current_containing_block_computed_style = Some(computed_style);
+            // The kept node carries the chain position for the next iteration.
+            last_kept_computed_style = Some(computed_style);
         }
 
         current_node = get_parent_node(&current_node);
diff --git a/packages/dom/src/utils/get_css_dimensions.rs b/packages/dom/src/utils/get_css_dimensions.rs
index 7b2a575..ee0ae1a 100644
--- a/packages/dom/src/utils/get_css_dimensions.rs
+++ b/packages/dom/src/utils/get_css_dimensions.rs
@@ -26,16 +26,15 @@ pub fn get_css_dimensions(element: &Element) -> CssDimensions {
         .parse::<f64>()
         .unwrap_or(0.0);
 
-    let offset_width;
-    let offset_height;
-    if is_html_element(element) {
+    let (offset_width, offset_height) = if is_html_element(element) {
         let element = element.unchecked_ref::<HtmlElement>();
-        offset_width = element.offset_width() as f64;
-        offset_height = element.offset_height() as f64;
+        (
+            element.offset_width() as f64,
+            element.offset_height() as f64,
+        )
     } else {
-        offset_width = width;
-        offset_height = height;
-    }
+        (width, height)
+    };
     let should_fallback = width.round() != offset_width || height.round() != offset_height;
 
     CssDimensions {
diff --git a/upstream.toml b/upstream.toml
index ef002fc..9664e46 100644
--- a/upstream.toml
+++ b/upstream.toml
@@ -1,5 +1,5 @@
 [releases]
-core = "1.7.5"
+core = "1.8.0"
 dom = "1.7.6"
 utils = "0.2.12"
 vue = "2.0.0"