It's indeed a problem with the customization of the notice popup box from your template.
In the file /shop/templates/r_glamour/scss/hydrogen/_hikashopstyles.scss
You have this code:
.notifyjs-metro-base {
@include box-shadow(0 6px 12px rgba(0, 0, 0, 0.12), 0 6px 24px rgba(0, 0, 0, 0.25) !important);
padding: 5px;
border-radius: 3px;
.image {
padding-left: 5px;
}
&.notifyjs-metro-info {
background-color: $base-color-1 !important;
border-color: $base-color-1 !important;
color: $white !important;
}
&.notifyjs-metro-error {
background-color: #DB2828 !important;
border-color: #DB2828 !important;
color: $white !important;
}
&.notifyjs-metro-success {
background-color: #21BA45 !important;
border-color: #21BA45 !important;
color: $white !important;
}
&.notifyjs-metro-warn, &.notifyjs-metro-warning {
background-color: #FBBD08 !important;
border-color: #FBBD08 !important;
color: $black !important;
}
}
which customizes the notification boxes for error messages and success messages, but not notice messages.
The line:
&.notifyjs-metro-warn, &.notifyjs-metro-warning {
should be changed to:
&.notifyjs-metro-warn, &.notifyjs-metro-warning, &.notifyjs-metro-notice {
and then it should display fine.
I would recommend you to report the issue to your template provider so that they can include the modification on their end.
That way, you won't get the issue again next time you update your template and the scss file is overwritten by the update process.