really good point in there:

At times it’s important to remember that websites don’t necessarily have to look exactly the same on every browser. Other than web developers, humans have little interest in that. Humans will seldom use different browsers. Unless there are gross differences across browsers, like using entirely different sets of font faces, humans are not going to care. We need to learn to let go. User-agent detection might not be the prettiest practice in our toolset, but it is available for us to temporarily patch over these kind of problems.