diff --git a/ui/src/components/image-lightbox.ts b/ui/src/components/image-lightbox.ts
index fd5558c197de..346176729eea 100644
--- a/ui/src/components/image-lightbox.ts
+++ b/ui/src/components/image-lightbox.ts
@@ -127,6 +127,13 @@ class OpenClawImageLightbox extends OpenClawLitElement {
     .close svg {
       width: 17px;
       height: 17px;
+      /* Shadow DOM: global icon stroke rules don't reach in here; without a
+         stroke the open-path x icon renders invisible. */
+      fill: none;
+      stroke: currentColor;
+      stroke-width: 2;
+      stroke-linecap: round;
+      stroke-linejoin: round;
     }
 
     .stage {