body {
   background-color: white;
   color: black;
   transition: background-color 0.3s, color 0.3s;
}

button {
   padding: 10px 20px;
   font-size: 16px;
   cursor: pointer;
   margin: 20px;
}

body.dark-mode {
   background-color: #121212;
   color: white;
}

button.dark-mode {
   background-color: #333;
   color: white;
}

.content {
   padding: 20px;
   text-align: center;
}