bootstrap tabs weird white box around text

[tim cross]

I am using tabs in Dreamweaver using bootstraps-4.3.1.css

The tab works fine on a web browser but when I view it on an iPhone or iPad and I keep clicking between the tab, in the end, you see a white box around the text within the tab as shown in photo below.

Not sure how to get rid of this error?? It does not show up all the time and sometimes you have to press it lots of times before the box appears 

http://tcdesignstamford.co.uk/test/test.html

[BenPleysier]

Fix these and all should be well: https://validator.w3.org/nu/?doc=http%3A%2F%2Ftcdesignstamford.co.uk%2Ftest%2Ftest.html

[Nancy OShea · Accepted solution]

It deosn't look like an error to me.  I think that's the ACTIVE/FOCUS state when you tap & hold the link.

See this Bootstrap Tab/Pill reference.

https://www.w3schools.com/bootstrap4/tryit.asp?filename=trybs_nav_pills_toggleable&stacked=h

[tim cross]

Thank You - there was a slight border on the Active/Focus file within the bootstrap CSS so have turned it off and now works perfectly 🙂