body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f7f9;
    color: #333;
    text-align: center;
}
main {
    max-width: 800px;
    margin: 20px auto;
    padding: 20px;
    background: white;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}
header h1 {
    background-color: #004d99;
    color: white;
    padding: 20px 0;
    margin: 0;
}
/* AQI Display Styling */
.aqi-value {
    font-size: 3em;
    font-weight: bold;
    display: inline-block;
    padding: 15px 30px;
    border-radius: 10px;
    margin: 15px 0;
    color: white;
}
/* Color Coding */
.good { background-color: #009966; } /* Green */
.moderate { background-color: #ffde33; color: #333; } /* Yellow */
.unhealthy-sensitive { background-color: #ff9933; } /* Orange */
.unhealthy { background-color: #cc0033; } /* Red */
.very-unhealthy { background-color: #660099; } /* Purple */
.hazardous { background-color: #7e0023; } /* Maroon */

/* Ad Container Styling (Crucial for AdSense) */
.ad-container {
    margin: 20px 0;
    padding: 10px;
    border: 1px dashed #ccc; /* Helps visually isolate the ad unit */
    min-height: 100px; /* Placeholder to reserve space */
    background-color: #fafafa;
    text-align: center;
}
.explanation {
    margin-top: 30px;
    font-size: 0.9em;
    color: #666;
}
footer {
    padding: 10px;
    margin-top: 20px;
    border-top: 1px solid #eee;
    color: #999;
}