userContent.css

@import url(global-colors.css);
@import url(userContent/AboutPages.css);
@import url(userContent/Addons.css);
@import url(userContent/ChromePages.css);
@import url(userContent/ContextMenu.css);
@import url(userContent/ErrorPages.css);
@import url(userContent/InContentNotifications.css);
@import url(userContent/InWindowLibrary.css);
@import url(userContent/PDFviewer.css);
@import url(userContent/ReaderView.css);
@import url(userContent/ViewSourcePage.css);
@import url(userContent/Websites.css);

/*++++++ Remove White Flickering +++++*/

@-moz-document url("about:home"),
url("about:blank"),
url("about:newtab"),
url("about:privatebrowsing"),
url("about:memory"),
url("about:performance"),
url("about:addons")
url-prefix("chrome://"),
{
  html,
  body {
    background-color: var(--Dark_BackgroundColor) !important;
  }
}

@-moz-document plain-text-document(), media-document(all), url(chrome://browser/content/webext-panels.xhtml)
{
  :root {
    background-color: var(--Dark_BackgroundColor) !important;
    color: var(--Dark_TextColor) !important;
  }

  @media (prefers-color-scheme: dark) {
    :root {
      color: var(--Dark_TextColor) !important;
      background-color: var(--Dark_BackgroundColor) !important;
    }

    body:not([style*="background"], [class], [id]) {
      background-color: var(--Dark_BackgroundColor) !important;
    }
  }
}

/*Custom Startpage*/
@-moz-document url-prefix(file:///)
{
  html,
  body,
  body :not(iframe) {
    background-color: /*#181a1b*/ var(--Dark_BackgroundColor) !important;
  }
}

/*Firefox Screenshots*/
.highlight-buttons > button {
  box-shadow: 0 0 0 1px rgba(12, 12, 13, 0.1), 0 2px 8px rgba(12, 12, 13, 0.1);
  background: var(--Dark_BackgroundColor) !important;
  border: 1px solid var(--Dark_BorderColor) !important;
  color: var(--Dark_TextColor) !important;
  padding: 5px !important;
  height: 30px !important;
  font-size: 13px !important;
  font-family: Fira Sans !important;
}

.highlight-buttons > button > img {
  height: 14px !important;
  width: 14px !important;
  filter: invert(0.4) !important;
}

.mover-target .mover {
  background-color: #dc2430 !important;
}

.preview-overlay .cancel-shot {
  padding: 5px 10px !important;
  border: 2px solid #dc2430 !important;
  font-family: Fira Sans !important;
  font-size: 14px !important;
}

.preview-overlay .preview-instructions {
  font-family: Fira Sans !important;
  font-size: 22px !important;
  padding-top: 40px !important;
  font-variant: all-petite-caps !important;
  line-height: 26px !important;
}

.all-buttons-container {
  background: transparent !important;
}

.all-buttons-container .visible {
  background-image: url("moz-extension://0d07c488-7765-4b75-8cd8-2eaf899b2084/icons/menu-visible.svg");
  background-color: #000 !important;
  color: #fff !important;
  font-family: Fira Sans !important;
  border: 1px solid #212121 !important;
  font-size: 14px !important;
  font-variant: petite-caps !important;
  padding: 50px 10px 5px !important;
}

.all-buttons-container .full-page {
  background-image: url("moz-extension://0d07c488-7765-4b75-8cd8-2eaf899b2084/icons/menu-fullpage.svg");
  background-color: #000 !important;
  color: #fff !important;
  font-family: Fira Sans !important;
  border: 1px solid #212121 !important;
  font-size: 14px !important;
  padding: 50px 10px 5px !important;
  background-size: 40px 35px;
  font-variant: petite-caps !important;
}