diff --git a/css/vips.css b/css/vips.css
index f19b35c14066a11ce3d9aedb240b4aa94df2e2d9..501d07b53768ff848e6bd1551bd1310006b95836 100644
--- a/css/vips.css
+++ b/css/vips.css
@@ -533,6 +533,7 @@ button.vips_file_upload:hover {
 }
 
 #character_picker .block button {
+    background-color: transparent;
     border: 0;
     border-radius: 0.25em;
     cursor: pointer;