userChrome.css

/*
 * Originally from:
 * http://forums.mozillazine.org/viewtopic.php?p=14404121#p14404121
 */

 #urlbar {
    position: relative;
    z-index: 1;
  }

  #identity-box:after {
    content: '';
    position: absolute;
    height: 100%;
    width: 100%;
    top: 0;
    left: 0;
    pointer-events: none;
    z-index: -1;
    background: white;
    opacity: 0.2;
  }


  /* There is also grantedPermissions, but irrelevant. */

  /* about:about */
  #urlbar[pageproxystate='valid'] #identity-box.unknownIdentity:after {
    background: #ff0039; /* Firefox Red 50 */
  }

  /* about:config */
  #urlbar[pageproxystate='valid'] #identity-box.chromeUI:after {
    background: #0a84ff; /* Firefox Blue 50 */
  }

  /* uBlock Origin Dashboard */
  #urlbar[pageproxystate='valid'] #identity-box.extensionPage:after {
    background: #45a1ff; /* Firefox Blue 40 */
  }

  /* https://www.github.com/ */
  #urlbar[pageproxystate='valid'] #identity-box.verifiedIdentity:after{
    background: #058b00; /* Firefox Green 70 */
  }

  /* https://www.google.com/ */
  #urlbar[pageproxystate='valid'] #identity-box.verifiedDomain:after{
    background: #12bc00; /* Firefox Green 60 */
  }

  /* https://mixed-script.badssl.com/ */
  #urlbar[pageproxystate='valid'] #identity-box.mixedActiveBlocked:after {
    background: #30e60b; /* Firefox Green 50 */
  }

  /* https://mixed.badssl.com/ */
  #urlbar[pageproxystate='valid'] #identity-box.mixedDisplayContent:after {
    background: #d7b600; /* Firefox Yellow 60 */
  }

  /* https://very.badssl.com/ */
  #urlbar[pageproxystate='valid'] #identity-box.mixedDisplayContentLoadedActiveBlocked:after {
    background: #d7b600; /* Firefox Yellow 60 */
  }

  /* https://self-signed.badssl.com/ but add certificate exception */
  #urlbar[pageproxystate='valid'] #identity-box.certUserOverridden:after {
    background: #ffe900; /* Firefox Yellow 50 */
  }

  /* Don't know an example for this */
#urlbar[pageproxystate='valid'] #identity-box.weakCipher:after {
    background: #a47f00; /* Firefox Yellow 70 */
  }

  /* https://mixed-script.badssl.com/ but disable protection */
  #urlbar[pageproxystate='valid'] #identity-box.mixedActiveContent:after {
    background: #d70022;  /* Firefox Red 60 */
  }

  /* http://http-login.badssl.com/ */
  #urlbar[pageproxystate='valid'] #identity-box.insecureLoginForms:after {
    background: #a4000f;  /* Firefox Red 70 */
  }

  @namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

/* hide the native tabs */
#TabsToolbar-customization-target {
    visibility: collapse;
}