Ionic 4 - How to change Toast button's style?

Hello there,
I have a custom button in toast, and I added cssClass to it, but I don’t know how to modify the button’s style, such as background-color, padding, width, etc.

A component contains the following code:

        this.toastInstance = await this.toastCtrl.create({
            cssClass: "custom-toast-error",
            duration: 0,
            showCloseButton: false,
            closeButtonText: "Close",
            position: "bottom",
            buttons: [{
                text: "",
                icon: "ios-close-circle",
                side: "start",
                cssClass: "custom-toast-error-button"

I know how to modify the style of toast by’.custom-toast-error’, but I can’t modify the style of button by’.custom-toast-error-button’.

Hi friend , Did you find a solution?