refactor: apply proposal by @ektrah

Author: danielpeintner

index.html

@@ -58,6 +58,10 @@
     <style>
       .rfc2119-assertion {
         background-color: light-dark(#e6e6e6, #223a2c);
+        background-color: #e6e6e6;
+      }
+      body.darkmode .rfc2119-assertion {
+        background-color: #223a2c;
       }
       .at-risk {
         background-color: yellow;