Captcha accessibility patch

web_src/css/index.css

@@ -99,3 +99,9 @@
     margin-left: 0 !important;
   }
 }
+
+.captcha-img {
+  width: min(400px, 100%);
+
+  /* rest in markup/dark.css */
+}

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();
+}