Set dark/light for web content

webviewInject.swift

private func setMode(_ isDark: Bool) {
    let mode = isDark ? "add" : "remove"
    let script = "document.body.classList.\(mode)(\"dark\");"

    webView.evaluateJavaScript(script) { result, error in
        if let err = error {
            os_log("%{public}s", log: logger, type: .error, "js error: \(err).")
        }
    }
}