body{background-color:#121212;color:#fff;font-family:Arial,sans-serif;margin:0;padding:0}#container{display:flex;flex-direction:column;align-items:center;justify-content:center;height:100vh}#header-container{margin-bottom:20px}#header{font-size:2rem}#button-container{display:flex;justify-content:space-around;width:80%;max-width:600px;margin-bottom:20px}#break-container,#session-container{text-align:center}#break-label,#session-label{font-size:1.2rem;margin-bottom:10px}#break-buttons,#session-buttons{display:flex;align-items:center}#break-counter,#session-counter{margin:0 10px;font-size:1.5rem}button{background-color:#333;color:#fff;border:none;padding:10px 20px;font-size:1rem;cursor:pointer;border-radius:5px;transition:background-color .3s}button:hover{background-color:#555}#timer-container{text-align:center;margin-bottom:20px}#timer-label{font-size:1.2rem;margin-bottom:10px}#time-left{font-size:3rem}#timer-buttons button{margin:0 10px}#start_stop,#reset{background-color:#444;border-radius:5px;padding:10px 20px}