diff --git a/browser/themes/shared/tabbrowser/tab-hover-preview.css b/browser/themes/shared/tabbrowser/tab-hover-preview.css
index 90680fb5870bd7387656d3066c39b6d6f80916bd..636c2f4c7cfda0280b24e40cf7613321bf1d3905 100644
--- a/browser/themes/shared/tabbrowser/tab-hover-preview.css
+++ b/browser/themes/shared/tabbrowser/tab-hover-preview.css
@@ -52,3 +52,24 @@
   from { opacity: 0; }
   to { opacity: 100; }
 }
+
+/**
+ * Zen overrides (try to avoid git conflicts as much as possible)
+ */
+
+.tab-preview-container {
+  --zen-border-color: #bdbcbc;
+  overflow: hidden;
+  border: 1px solid var(--zen-border-color);
+}
+
+@media (prefers-color-scheme: dark) {
+  .tab-preview-container {
+    --zen-border-color: #565656;
+  }
+}
+
+.tab-preview-thumbnail-container img,
+.tab-preview-thumbnail-container canvas {
+  border-top: 1px solid var(--zen-border-color);
+}
\ No newline at end of file
