signal-desktop/stylesheets/_titlebar.scss

// Copyright 2022 Signal Messenger, LLC
// SPDX-License-Identifier: AGPL-3.0-only

body {
  // Overridden by ts/background.ts
  --zoom-factor: 1;

  // These should match the logic in `ts/types/Settings.ts`'s `getTitleBarVisibility`.
  //
  // It'd be great if we could use the `:fullscreen` selector here, but that does not seem
  //   to work with Electron, at least on macOS.
  --title-bar-drag-area-height: 0px; // Needs to have a unit to work with `calc()`.
  &.os-macos:not(.full-screen) {
    --title-bar-drag-area-height: calc(28px / var(--zoom-factor));
  }
}