diff --git a/CHANGELOG.md b/CHANGELOG.md
index ba32d5c..6145b09 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ### Changed
 
+- Reduce the vertical gap between object rows by at least half (#292).
+
 - Point new installs and documentation links to Ambiguous-Interactive/DxVisualizer. Update site bookmarks to <https://ambiguous-interactive.github.io/DxVisualizer/>; the old Pages
   site does not redirect. Existing Git installs keep working (#151).
 
diff --git a/Editor/DataVisualizer/DataVisualizer.cs b/Editor/DataVisualizer/DataVisualizer.cs
index 72b5fda..6cbad22 100644
--- a/Editor/DataVisualizer/DataVisualizer.cs
+++ b/Editor/DataVisualizer/DataVisualizer.cs
@@ -85,11 +85,10 @@ overwrite the saved preferred size.
         private const int AsyncLoadPriorityBatchSize = 100;
 
         /*
-            Uniform row height for the virtualized object ListView. Measured live: the .object-item
-            box renders at ~40px; the slot is forced to this height and centers the box, so the extra
-            6px becomes a 3px gap above and below each row.
+            Keep the fixed-height object ListView slots close to the card height to reduce
+            empty vertical space. Card padding and controls keep their existing dimensions.
         */
-        private const float ObjectRowFixedHeight = 46f;
+        private const float ObjectRowFixedHeight = 40f;
 
         internal static DataVisualizer Instance;
 
diff --git a/Tests/Editor/ObjectRowLayoutTests.cs b/Tests/Editor/ObjectRowLayoutTests.cs
new file mode 100644
index 0000000..2463ce3
--- /dev/null
+++ b/Tests/Editor/ObjectRowLayoutTests.cs
@@ -0,0 +1,74 @@
+namespace WallstopStudios.DataVisualizer.Tests.Editor
+{
+    using System.Collections;
+    using System.Reflection;
+    using NUnit.Framework;
+    using UnityEditor;
+    using UnityEngine;
+    using UnityEngine.TestTools;
+    using UnityEngine.UIElements;
+    using WallstopStudios.DataVisualizer.Editor.Styles;
+    using DataVisualizerWindow = WallstopStudios.DataVisualizer.Editor.DataVisualizer;
+
+    public sealed class ObjectRowLayoutTests
+    {
+        [UnityTest]
+        public IEnumerator ShouldKeepCompactRowsAndControlsInsideEveryShippedTheme()
+        {
+            using TestCleanupScope cleanup = new();
+            FieldInfo instanceField = typeof(DataVisualizerWindow).GetField("Instance", BindingFlags.Static | BindingFlags.NonPublic);
+            object previousInstance = instanceField.GetValue(null);
+            cleanup.Defer(() => instanceField.SetValue(null, previousInstance));
+            DataVisualizerWindow owner = ScriptableObject.CreateInstance<DataVisualizerWindow>();
+            cleanup.Defer(() => Object.DestroyImmediate(owner));
+            MethodInfo makeRow = typeof(DataVisualizerWindow).GetMethod("MakeObjectRow", BindingFlags.Instance | BindingFlags.NonPublic);
+            LayoutTestWindow window = ScriptableObject.CreateInstance<LayoutTestWindow>();
+            cleanup.Defer(window.Close);
+            window.position = new Rect(100, 100, 700, 200);
+            VisualElement root = window.rootVisualElement;
+            root.AddToClassList("dataviz-root");
+            const string folder = "Packages/com.wallstop-studios.data-visualizer/Editor/DataVisualizer/Styles/";
+            root.styleSheets.Add(AssetDatabase.LoadAssetAtPath<StyleSheet>(folder + "DataVisualizerStyles.uss"));
+            VisualElement first = (VisualElement)makeRow.Invoke(owner, null);
+            VisualElement second = (VisualElement)makeRow.Invoke(owner, null);
+            first.Q<Label>("object-item-label").text = "First object";
+            second.Q<Label>("object-item-label").text = "Second object";
+            root.Add(first);
+            root.Add(second);
+            DataVisualizerThemeSelection selection = new();
+            cleanup.Defer(() => selection.Apply(null, null));
+            window.ShowUtility();
+
+            string[] themes = { "Dx", "Classic", "Nord", "Dracula", "Compact", "Minimal" };
+            foreach (string name in themes)
+            {
+                DataVisualizerThemeSettings theme = AssetDatabase.LoadAssetAtPath<DataVisualizerThemeSettings>(folder + name + ".asset");
+                Assert.That(theme != null, name);
+                selection.Apply(root, theme);
+                yield return null;
+                EditorSurfaceCapture.SettleLayout(window);
+                VisualElement firstBox = first.Q("object-item-box");
+                VisualElement secondBox = second.Q("object-item-box");
+                float gap = secondBox.worldBound.yMin - firstBox.worldBound.yMax;
+                Assert.That(0 <= gap, name + " cards must not overlap");
+                if (name == "Dx")
+                {
+                    Assert.LessOrEqual(gap, 5f, "halve the previous 10-point default gap");
+                }
+
+                foreach (VisualElement row in new[] { first, second })
+                {
+                    VisualElement box = row.Q("object-item-box");
+                    Assert.That(row.worldBound.yMin <= box.worldBound.yMin, name);
+                    Assert.That(box.worldBound.yMax <= row.worldBound.yMax, name);
+                    foreach (Button button in box.Query<Button>().ToList())
+                    {
+                        Assert.That(0 < button.worldBound.height, name);
+                        Assert.That(box.worldBound.yMin <= button.worldBound.yMin, name);
+                        Assert.That(button.worldBound.yMax <= box.worldBound.yMax, name);
+                    }
+                }
+            }
+        }
+    }
+}
diff --git a/Tests/Editor/ObjectRowLayoutTests.cs.meta b/Tests/Editor/ObjectRowLayoutTests.cs.meta
new file mode 100644
index 0000000..ac83292
--- /dev/null
+++ b/Tests/Editor/ObjectRowLayoutTests.cs.meta
@@ -0,0 +1,2 @@
+fileFormatVersion: 2
+guid: 9629a42f1faf4f2ca8d77c1258b7b231
diff --git a/docs/images/data-visualizer-layout.png b/docs/images/data-visualizer-layout.png
index 2189742..eea35e1 100644
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diff --git a/docs/images/data-visualizer-layout.webp b/docs/images/data-visualizer-layout.webp
index 1f04fdf..256de8a 100644
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