Format Events List Widget Title

I'm trying to change the look of the Events List Widget so that it matches other sidebar widgets.
The CSS below in the Additional CSS should just about do the trick, but it appears to be overridden by CSS generated by the widget.
Some of the CSS below is having an effect (Background-color), but not the rest of it.

.tribe-events-widget
{
margin-bottom:4px;
background-color:white;
}

.tribe-common h2
{
font-size:22px;
font-weight:400;
color:red;
}

The EventsCalendar Support site documents a method of overwriting CSS here, but it does not seem to work.
- https://theeventscalendar.com/knowledgebase/k/customizing-css/

I have followed their advice and put the CSS below in the file they suggest but it does not appear to be loaded at all.

.tribe-events-widget {margin-bottom:4px;
background-color:white;}

.tribe-common h2
{
font-size:22px;
font-weight:400;
color:blue;
}
The color:red and color:blue are present only for debugging purposes.

Here is the URL where you can inspect the behaviour as it is now:

https://forourgrandchildren.ca/

I hope you can help me as you usually do.