body { 
margin: 0; 
font-family: Arial, sans-serif; 
background: #f4f4f4; 
color: #222; 
} 
header, footer { 
background: #bfa1b2; 
color: white; 
padding: 16px; 
text-align: center; 
} 
main { 
max-width: 800px; 
margin: 
0 auto; 
padding: 16px; 
} 
section { 
background: white; 
border: 2px solid #ddd; 
padding: 16px; 
margin-bottom: 16px; 
} 
button { 
padding: 10px 14px; 
cursor: pointer; 
} img { 
display: block; 
max-width: 100%; 
height: auto; 
margin-top: 10px; 
border: 4px solid #222; 
} 
/* THIS is what "darkTheme" means */ 
.darkTheme { 
background: #111; 
color: #f0f0f0; 
} 
.darkTheme header, .darkTheme footer { 
background: #A1BFAE; 
color: #111; } 
.darkTheme section { 
background: #1d1d1d; 
border-color: #A1BFAE; } 
.darkTheme img { 
border-color: #00ffaa; 
}