diff --git a/ui/src/components/MarkdownDocumentCardStyles.test.ts b/ui/src/components/MarkdownDocumentCardStyles.test.ts
new file mode 100644
index 00000000000..3fcfd752a62
--- /dev/null
+++ b/ui/src/components/MarkdownDocumentCardStyles.test.ts
@@ -0,0 +1,24 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+const stylesheet = readFileSync(fileURLToPath(new URL("../index.css", import.meta.url)), "utf8");
+
+function cssBlock(selector: string): string {
+  const start = stylesheet.indexOf(`${selector} {`);
+  expect(start, `Missing CSS selector: ${selector}`).toBeGreaterThanOrEqual(0);
+
+  const bodyStart = stylesheet.indexOf("{", start);
+  const bodyEnd = stylesheet.indexOf("\n}", bodyStart);
+  expect(bodyStart, `Missing CSS block start: ${selector}`).toBeGreaterThanOrEqual(0);
+  expect(bodyEnd, `Missing CSS block end: ${selector}`).toBeGreaterThan(bodyStart);
+
+  return stylesheet.slice(bodyStart + 1, bodyEnd);
+}
+
+describe("markdown document card styles", () => {
+  it("removes the inherited markdown link underline so the card label shows one underline", () => {
+    expect(cssBlock(".paperclip-markdown a")).toContain("text-decoration: underline");
+    expect(cssBlock(".paperclip-markdown a[data-sidebar-document-link]")).toContain("text-decoration: none");
+  });
+});
diff --git a/ui/src/index.css b/ui/src/index.css
index 15eff463006..d9e0f9aa191 100644
--- a/ui/src/index.css
+++ b/ui/src/index.css
@@ -2549,6 +2549,12 @@ a.paperclip-mention-chip[data-mention-kind="agent"]::before {
   text-decoration: none;
 }
 
+/* Document cards underline only their label span; the card itself must not
+   inherit the markdown link underline, or the label shows two lines. */
+.paperclip-markdown a[data-sidebar-document-link] {
+  text-decoration: none;
+}
+
 .paperclip-markdown a.paperclip-mention-chip[data-mention-kind="issue"] {
   border-color: color-mix(in oklab, var(--foreground) 14%, var(--border) 86%);
   background: color-mix(in oklab, var(--accent) 42%, transparent);