diff --git a/ui/dev/harness.html b/ui/dev/harness.html
index cbab2cc..4497084 100644
--- a/ui/dev/harness.html
+++ b/ui/dev/harness.html
@@ -138,6 +138,36 @@
       </figure>
     </div>
 
+    <h2>2b — Selection geometry (rows must NOT shift when selected)</h2>
+    <div class="pair">
+      <figure class="cell" style="margin:0">
+        <figcaption>no selection</figcaption>
+        <table class="is-active">
+          <colgroup><col /><col style="width:6rem" /></colgroup>
+          <thead><tr><th>Name</th><th>Size</th></tr></thead>
+          <tbody>
+            <tr><td>aaa.txt</td><td>1 KB</td></tr>
+            <tr><td>bbb.txt</td><td>2 KB</td></tr>
+            <tr><td>ccc.txt</td><td>3 KB</td></tr>
+            <tr><td>ddd.txt</td><td>4 KB</td></tr>
+          </tbody>
+        </table>
+      </figure>
+      <figure class="cell" style="margin:0">
+        <figcaption>middle row selected — baselines must still line up</figcaption>
+        <table class="is-active">
+          <colgroup><col /><col style="width:6rem" /></colgroup>
+          <thead><tr><th>Name</th><th>Size</th></tr></thead>
+          <tbody>
+            <tr><td>aaa.txt</td><td>1 KB</td></tr>
+            <tr class="highlighted"><td>bbb.txt</td><td>2 KB</td></tr>
+            <tr><td>ccc.txt</td><td>3 KB</td></tr>
+            <tr><td>ddd.txt</td><td>4 KB</td></tr>
+          </tbody>
+        </table>
+      </figure>
+    </div>
+
     <h2>3 — Context menu</h2>
     <div class="pair">
       <figure class="cell" style="margin:0">
diff --git a/ui/src/styles.css b/ui/src/styles.css
index 0fab48e..58a49c6 100644
--- a/ui/src/styles.css
+++ b/ui/src/styles.css
@@ -639,6 +639,21 @@ body {
     border-color: var(--w7-li-bd-hl);
   }
 
+  /* Constant row geometry. 7.css gives ONLY tr.highlighted a 1px border, and
+     the table is border-collapse: collapse — so a selected row physically grew
+     1px at top and bottom and shoved every row below it down by 2px as the
+     cursor moved. Every row reserves that border instead, transparent when not
+     selected, so selecting changes colour and nothing else.
+     NOTE: this sits in `skinfix`, which outranks `skin` by LAYER regardless of
+     specificity, so it would also blank 7.css's highlight border — both
+     selected states therefore restate their border-color below. */
+  .win7 table > tbody > tr {
+    border: 1px solid transparent;
+  }
+  .win7 table > tbody > tr.highlighted {
+    border-color: var(--w7-li-bd-hl);
+  }
+
   /* Pane-focus model (commander convention, matching Win7 Explorer):
      the CURSOR ROW always carries the selection band in BOTH panels —
      tr.highlighted covers "selected via Space" AND "cursor row" (the template