// Create CSS file
file_put_contents(plugin_dir_path(__FILE__) . 'css/konkood-sand-calculator.css', '
.konkood-sand-calculator {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    border: 1px solid #ddd;
    border-radius: 5px;
}
.form-group {
    margin-bottom: 15px;
}
.form-group label {
    display: block;
    margin-bottom: 5px;
}
.form-group input[type="number"],
.form-group select {
    width: 100%;
    padding: 8px;
    border: 1px solid #ccc;
    border-radius: 4px;
}
.unit-label {
    margin-left: 10px;
}
button#calculate-btn {
    background-color: #0073aa;
    color: #fff;
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}
button#calculate-btn:hover {
    background-color: #005177;
}
#result {
    margin-top: 20px;
    padding: 15px;
    background-color: #f9f9f9;
    border-radius: 4px;
}
');