'Invalid request token' error message

[True Wolf]

I am using the Sidebar Redux plugin. It's been working fine, no problems. I wanted to remove the moz border and remove any spacing between the sidebars so they would flow together, so I headed over to the thread for the plugin to see if Brian had posted anything for this to someone else. He had, and I used the piece of code he'd provided as another member claimed it worked.

It was simply to add this into the bottom of the style sheet:

.sidebarr-main .content-box {
  border-color: @container_outer_border_color;
  padding: 0px !important;
  border-radius: 0px;
}

However, whenever I tried, when I saved it just popped up with this message

Invalid request token / possible request forgery. If you received this
message in error, please go back, refresh, and try again.

I did as it said, went back, refreshed, tried again, etc. I googled this error and tried some of the solutions given to others; I shut down my computer, tried again, same message. Closed Firefox, tried again, same message. New tab, same message, etc.

I'm not entirely sure what this message even means, but was wondering why I keep getting it when changing my style sheet? And if there are any possible fixes.

[Brian]

Hi, True Wolf.

Have you tried saving it with private browsing enabled (Ctrl+Shift+P)?

This runs the browser without any of your previous cookies or cache files until you switch back or close it.

[True Wolf]

I just tried. I'm pretty sure it used previous cookies and cache files as it had records of my previous logins, etc. It just said that it wouldn't record anything. Got the same message :/

[Brian]

I brought this up in our meeting this morning. We're going to have a look at it since it seems to be happening to multiple users lately.

I'll post again if I have any updates.

[True Wolf]

Ok, thanks a lot!