diff --git a/web_src/css/index.css b/web_src/css/index.css
index 67f01bc062..843e73d8f0 100644
--- a/web_src/css/index.css
+++ b/web_src/css/index.css
@@ -99,3 +99,9 @@
     margin-left: 0 !important;
   }
 }
+
+.captcha-img {
+  width: min(400px, 100%);
+
+  /* rest in markup/dark.css */
+}
diff --git a/web_src/css/markup/dark.css b/web_src/css/markup/dark.css
index 700a48518e..09957f2108 100644
--- a/web_src/css/markup/dark.css
+++ b/web_src/css/markup/dark.css
@@ -11,3 +11,12 @@
 .markup [href$="#dark-mode-only"] {
   display: unset;
 }
+
+/*
+git724 tweaks; the reason we're doing this here is because dark vanilla templates use this
+there's no other way to do it
+*/
+
+.captcha-img {
+  filter: invert();
+}