Hello There,
That is the alert box generated by WooCommerce. To change the colors, please make use of this example code:
.x-alert-danger, .buddypress #message.error, .bbp-template-notice.error {
background-color: #e5e5e5;
border-color: #e5e5e5;
color: #000;
}
.woocommerce-message a,
.woocommerce-error a,
.woocommerce-info a {
border-color: #fff;
background-color: #fff;
text-shadow: none;
text-decoration: none;
}
.woocommerce-message a:hover,
.woocommerce-error a:hover,
.woocommerce-info a:hover {
border-color: #f0f0f0;
background-color: #f0f0f0;
}
Feel free to change the colors as needed.