Well… I played with a bunch of things to make it work and I’m not what eventually did it for me…
I guess - the fact that the CSS didn’t reside under the static url folder in the flask server was the issue - but like I said… there might have been additional contributing factors…
Bottom line, in the my.css file:
.modebar {
display: none !important;
}
And then:
my_css_url = "/static/my.css"
app.css.append_css({
“external_url”: my_css_url
})
Worked!
Thanks guys!!