[boxzilla-close]No, thanks![/boxzilla-close] color issue

Hello,

I have been using Boxzilla for a while and had some issues with the X (close button) at the top. One of your plugin developers told me to add the following in the additional css so that the close button appears: `.boxzilla-close-icon {
opacity: 1 !important;
color: #FFFFFF !important;`
}
For some reason, however, that has stopped working. So instead of the X (close button at the top right), I decided I will just use this instead: [boxzilla-close]No, thanks![/boxzilla-close]

While it works fine, the issue is whenever I try to assign the “No, thanks!” a white color, it does not work. It always displays a darker color. Please check the screenshot below. Secondly, I have tried editing this both via the visual editor and the text editor. I am not sure why this is happening.

The link to the staging is:
https://wordpress-601622-2862723.cloudwaysapps.com Just scroll down a bit and the popup will open at the bottom right

The screenshot of how the “No, thanks” looks is here. You can see that the black background makes it very difficult to see.
https://ibb.co/G0qW2Pz

The page I need help with: [log in to see the link]