body{background-color:#fff;color:#000;transition:background-color 0.3s,color 0.3s}body.dark-mode{background-color:#121212;color:#fff}#dark-mode-toggle{position:fixed;bottom:20px;right:20px;padding:10px 20px;background-color:#0073aa;color:#fff;border:none;border-radius:5px;cursor:pointer;z-index:1000}#dark-mode-toggle:hover{background-color:#005177}