Redactor inside Craft CMS is not applying format classes - redactor

Question

I'm having trouble getting Craft 3 to apply the custom classes that I've created in my Standard.json file. I have set up the Redactor config in the Craft CP to use Standard.
My Standard.json file looks like this:
{
"buttons": ["formatting", "bold", "italic", "unorderedlist", "orderedlist",
"link", "image", "video"],
"plugins": ["fullscreen", "video"],
"toolbarFixed": true,
"formattingAdd": {
"article-para": {
"title": "Article Paragraph",
"args": [
"p",
"class",
"para"
]
},
"article-heading": {
"title": "Article Heading",
"args": [
"h3",
"class",
"h2 txt-black mb"
]
}
}
}
Both Article Heading and Article Paragraph show up in my dropdown of formats, but when I select them, the elements don't change visually or in my inspector.
Any help would be appreciated.

Answer 1

Your json formatting appears to be off at the point that you set the args. Try this:
{
"buttons": ["formatting", "bold", "italic", "unorderedlist", "orderedlist",
"link", "image", "video"],
"plugins": ["fullscreen", "video"],
"toolbarFixed": true,
"formattingAdd": {
"article-para": {
"title": "Article Paragraph",
"args": {
"tag": "p",
"class": "para"
}
},
"article-heading": {
"title": "Article Heading",
"args": {
"tag": "h3",
"class": "h2 txt-black mb"
}
}
}
}
That should do it.