diff --git a/boards/static/css/base.css b/boards/static/css/base.css
--- a/boards/static/css/base.css
+++ b/boards/static/css/base.css
@@ -148,7 +148,7 @@ textarea, input {
     filter: invert(100%);
 }
 
-.monochrome > .image > .thumb > img, .monochrome .url-image, .monochrome.img-full {
+.monochrome > .image, .monochrome .url-image, .monochrome.img-full {
     filter: grayscale(100%);
 }