ASP.NET checkboxes - does not highlight when has focus

I have a small but annoying issue in my web app. I have multiple web forms that have checkboxes. In some of them If I have focus on a checkbox you can see a little black outline around it as shown below:

In some places, I am able to see the black outline for all checkboxes. In other, I cannot see the black outline when have focus.

In properties window both shows as System.Web.UI.WebControls.Checkbox

I know this is a small issue, its just I'm trying to be consistent everywhere. Does anyone what could cause this?