body {
 background-color: #f0f0f0; /* Light grey */
 font-family: Arial, sans-serif;
}
.dark {
 background-color: #333; /* Dark grey */
 color: #fff; /* White */
}
.dark h1 {
 color: #66d9ef; /* Light blue */
}
.dark h2 {
 color: #8bc34a; /* Light green */
}