body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #f8f9fa;
    color: #333;
    text-align: center;
}

header {
    background: #0077b6;
    color: #fff;
    padding: 1rem 0;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
}

header a {
    color: #fff;
    text-decoration: none;
    margin: 0 1rem;
    font-weight: bold;
}

header .logo a {
    font-size: 1.5rem;
}

.container {
    max-width: 800px;
    margin: 2rem auto;
    padding: 1rem;
    background: #fff;
    box-shadow: 0px 0px 10px rgba(0,0,0,0.1);
    border-radius: 8px;
}

.aqi-box {
    padding: 1.5rem;
    margin: 1rem 0;
    border-radius: 8px;
    color: #fff;
}

.aqi-box.good { background: #28a745; }
.aqi-box.moderate { background: #ffc107; color: #333; }
.aqi-box.unhealthy, .aqi-box['unhealthy for sensitive'] { background: #fd7e14; }
.aqi-box['very unhealthy'] { background: #dc3545; }

form {
    margin-top: 1rem;
}

input[type="text"], input[type="number"], select {
    padding: 0.5rem;
    margin: 0.5rem;
    width: 60%;
    max-width: 300px;
    border: 1px solid #ccc;
    border-radius: 4px;
}

button {
    padding: 0.5rem 1rem;
    background: #0077b6;
    color: #fff;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

button:hover {
    background: #0096c7;
}

footer {
    margin-top: 2rem;
    padding: 1rem;
    background: #f1f1f1;
    font-size: 0.9rem;
}