diff --git a/apps/web/src/components/files/fileSurfaceChrome.tsx b/apps/web/src/components/files/fileSurfaceChrome.tsx
index d5263f73377c82a5712487fec62ec985bd874a9c..184c5626e90f273a237b23c490b70e8c4c76491b 100644
--- a/apps/web/src/components/files/fileSurfaceChrome.tsx
+++ b/apps/web/src/components/files/fileSurfaceChrome.tsx
@@ -29,8 +29,11 @@ export const FILE_LINK_REVEAL_UNSAFE_CSS = `
     color: var(--code-foreground, var(--foreground)) !important;
   }
 
+  /* Tint through --diffs-line-bg, not background-color. The editor paints row
+     tints on a layer below its text selection; a background on the row itself
+     covers the selection and makes selected text on this line invisible. */
   [${FILE_LINK_REVEAL_ATTRIBUTE}][data-line] {
-    background-color: light-dark(
+    --diffs-line-bg: light-dark(
       color-mix(
         in lab,
         var(--diffs-computed-diff-line-bg) 82%,