Custom Angular Checkbox with [(ngModel)] Support

Recently, I needed to add some custom styles to a checkbox in an Angular app. I found a simple example of what I wanted to do, implemented entirely with CSS and HTML, and containing no imperative code. Delighted with this discovery, I copied the CSS into my page and got it working with a few tweaks. Then I wondered what it would take to turn it into a custom component I could reuse. As it turns out, it was harder than I thought, but not overwhelming. The solution is described here.