diff --git a/src/app/view/mod.rs b/src/app/view/mod.rs
index 20ee91047..363cfb635 100644
--- a/src/app/view/mod.rs
+++ b/src/app/view/mod.rs
@@ -34,11 +34,13 @@ use viewcube::{viewcube_nav_controls, viewcube_ucs_picker, UCS_PICKER_W};
 pub(in crate::app) use overlay::{MTEXT_TEXT_ID, TEXT_INLINE_ID};
 
 const VIEWCUBE_HIT_SIZE: f32 = VIEWCUBE_REGION_PX;
+/// The desk shown around the sheet, as the widget wants it. One definition,
+/// shared with the renderer that clears the sheet viewport to the same thing.
 const PAPER_SPACE_BACKGROUND: Color = Color {
-    r: 138.0 / 255.0,
-    g: 138.0 / 255.0,
-    b: 138.0 / 255.0,
-    a: 1.0,
+    r: crate::scene::PAPER_DESK_COLOR[0],
+    g: crate::scene::PAPER_DESK_COLOR[1],
+    b: crate::scene::PAPER_DESK_COLOR[2],
+    a: crate::scene::PAPER_DESK_COLOR[3],
 };
 
 /// Base surface directly under the crosshair. Paper content viewports render
diff --git a/src/scene/mod.rs b/src/scene/mod.rs
index dd84edd41..fc7c4e8fa 100644
--- a/src/scene/mod.rs
+++ b/src/scene/mod.rs
@@ -285,6 +285,12 @@ struct GeometryDelta {
     full: bool,
 }
 
+/// The desk a paper layout lays its sheet on — the surface visible around the
+/// page. Distinct from both the page (`paper_bg_color`) and the model canvas
+/// (`bg_color`); if the desk took either of those colours the page edge would
+/// vanish into its own surround.
+pub const PAPER_DESK_COLOR: [f32; 4] = [138.0 / 255.0, 138.0 / 255.0, 138.0 / 255.0, 1.0];
+
 const CACHE_CATEGORY_ANNOTATIVE: u16 = 1 << 0;
 const CACHE_CATEGORY_HATCH: u16 = 1 << 1;
 const CACHE_CATEGORY_WIPEOUT: u16 = 1 << 2;
diff --git a/src/scene/pipeline/mod.rs b/src/scene/pipeline/mod.rs
index f09810e65..5b0c172a1 100644
--- a/src/scene/pipeline/mod.rs
+++ b/src/scene/pipeline/mod.rs
@@ -340,6 +340,9 @@ pub struct Pipeline {
     /// `render` skips the (per-pixel, GPU-dominating) hatch pass this frame. The
     /// scene-render cache holds the full-quality frame once the view settles.
     pub skip_hatch_frame: bool,
+    /// Skip the canvas entirely — no clear colour, no background pass — so
+    /// whatever was drawn underneath this viewport shows through it.
+    pub skip_background: bool,
     /// Stable identity of the viewport that last used this (index-addressed)
     /// pipeline slot. The renderer's viewport list drops off-canvas viewports,
     /// so a slot can be reused by a *different* viewport across frames; when the
@@ -2015,6 +2018,7 @@ impl Pipeline {
             render_sig: u64::MAX,
             skip_geometry: false,
             skip_hatch_frame: false,
+            skip_background: false,
             slot_id: u64::MAX,
         }
     }
@@ -3282,7 +3286,7 @@ impl Pipeline {
         };
         let msaa = &self.msaa_view;
         let [r, g, b, a] = bg_color;
-        let clear_color = if self.clip_boundary.is_some() {
+        let clear_color = if self.clip_boundary.is_some() || self.skip_background {
             wgpu::Color::TRANSPARENT
         } else {
             wgpu::Color {
@@ -3393,10 +3397,15 @@ impl Pipeline {
                 pass.set_vertex_buffer(0, vbuf.slice(..));
                 pass.draw(0..*vcount, 0..1);
             }
-            pass.set_pipeline(&self.background_pipeline);
-            pass.set_bind_group(0, &self.uniform_bind_group, &[]);
-            pass.set_stencil_reference(stencil_ref);
-            pass.draw(0..3, 0..1);
+            // The background shader returns an opaque colour whatever alpha it
+            // is handed, so a see-through viewport cannot be asked for as a
+            // transparent background — the pass has to not run.
+            if !self.skip_background {
+                pass.set_pipeline(&self.background_pipeline);
+                pass.set_bind_group(0, &self.uniform_bind_group, &[]);
+                pass.set_stencil_reference(stencil_ref);
+                pass.draw(0..3, 0..1);
+            }
             // The capability-selected façade dispatches storage or texture
             // draws before wires so outlines remain on top in either backend.
             // Skipped while navigating because per-pixel hatch work dominates
diff --git a/src/scene/view/render.rs b/src/scene/view/render.rs
index 96cb7819c..c6ead7099 100644
--- a/src/scene/view/render.rs
+++ b/src/scene/view/render.rs
@@ -202,6 +202,10 @@ pub struct ViewportData {
     /// into the render signature so the settle frame re-renders hatches once and
     /// the scene-render cache holds it. See [`Scene::navigating_lod`].
     pub(in crate::scene) skip_hatch: bool,
+    /// True when this viewport must not paint a canvas of its own. A floating
+    /// viewport on a paper layout sits ON the sheet: anything it painted first
+    /// would cover the page it is supposed to be a window in.
+    pub(in crate::scene) skip_background: bool,
     pub(in crate::scene) geometry_epoch: u64,
     /// Camera generation captured when this Primitive was assembled. Paired
     /// with `geometry_epoch` so the per-frame scissor / LOD recompute runs.
@@ -434,6 +438,7 @@ impl shader::Primitive for Primitive {
             inner.skip_geometry = skip;
             // Interaction LOD: skip the hatch draw this frame while navigating.
             inner.skip_hatch_frame = vp.skip_hatch;
+            inner.skip_background = vp.skip_background;
             if skip {
                 if vp.show_viewcube {
                     inner.viewcube.upload(
@@ -1250,6 +1255,7 @@ fn render_signature(vp: &ViewportData, clip_w: u32, clip_h: u32) -> u64 {
     // Interaction-LOD hatch suppression: differs the signature so the settle
     // frame (skip_hatch flips false) re-renders with hatches and re-caches.
     vp.skip_hatch.hash(&mut h);
+    vp.skip_background.hash(&mut h);
     clip_w.hash(&mut h);
     clip_h.hash(&mut h);
     // Live overlay (command preview / interim / grip drag). Small — a handful
@@ -1912,7 +1918,19 @@ impl Scene {
         &self,
         viewport: &ViewportInstance,
     ) -> ViewportDisplaySettings {
+        // What lies behind a viewport depends on what the viewport is. The
+        // full-canvas paper sheet shows the desk, and the page is drawn on top
+        // of it by `paper_sheet_fill` — give the desk the page's own colour and
+        // the edge disappears into a same-coloured surround that no amount of
+        // zooming out reveals. A floating viewport sits ON that sheet, so it
+        // paints no canvas at all; anything else would erase the page beneath
+        // it. Only model space clears to the editor background.
         let canvas_background = if viewport.paper_sheet {
+            crate::scene::PAPER_DESK_COLOR
+        } else if self.current_layout != "Model" {
+            // This viewport paints no canvas of its own (`skip_background`),
+            // but shading and fog still blend toward whatever is behind it —
+            // and behind a floating viewport is the page.
             self.paper_bg_color
         } else {
             self.bg_color
@@ -3594,6 +3612,7 @@ impl Scene {
             // (hatched) frame once it settles. Only applied to the on-screen
             // Model / paper content — the paper *sheet* keeps its fills.
             skip_hatch: self.hatch_lod_enabled() && !inst.paper_sheet && self.navigating_lod(),
+            skip_background: !inst.paper_sheet && self.current_layout != "Model",
             geometry_epoch: self.geometry_epoch,
             camera_generation: self.camera_generation,
             wire_content_id,