URL stamps should also be monochrome

boards/static/css/base.css

@@ -144,9 +144,12 b' textarea, input {'
     opacity: 1;
 }
 
-.monochrome > .image > .thumb > img, .monochrome.img-full {
+.url-image:hover, .monochrome .url-image:hover {
+    filter: invert(100%);
+}
+
+.monochrome > .image > .thumb > img, .monochrome .url-image, .monochrome.img-full {
     filter: grayscale(100%);
-    -webkit-filter: grayscale(100%);
 }
 
 #quote-button {
@@ -165,10 +168,6 b' textarea, input {'
     cursor: help;
 }
 
-.url-image:hover {
-    filter: invert(100%);
-}
-
 .landing-tags, .landing-images {
     max-width: 800px;
     margin-left: auto;