Personalization: remove button shadow

Make the button more to spec by removing the shadow.

Bug: b/194530310
Test: manually
Change-Id: Id38192063cbe27436c9e1e6d71cadf194896bc1a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3056720
Reviewed-by: Yue Li <updowndota@chromium.org>
Commit-Queue: Jason Thai <jasontt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#905862}
diff --git a/chromeos/components/personalization_app/resources/trusted/wallpaper_selected_element.html b/chromeos/components/personalization_app/resources/trusted/wallpaper_selected_element.html
index 380d85a7..ba7e060 100644
--- a/chromeos/components/personalization_app/resources/trusted/wallpaper_selected_element.html
+++ b/chromeos/components/personalization_app/resources/trusted/wallpaper_selected_element.html
@@ -73,6 +73,7 @@
     padding: 16px;
     margin-inline-end: 8px;
     border-radius: 16px;
+    box-shadow: none;
   }
 </style>
 <header id="container" tabindex="0" aria-label="[[getAriaLabel_(image_)]]"