title: Vertically center element on HTML page with some content on top (Bootstrap)
body: <p>I am building a website using bootstrap, which has some (minimal) content on top (basically title, subtitle, and a navigation bar). I would like to be able to center a div both horizontally and vertically. The contents of this div will be something small, like a login or search widget.</p>
  
  <p>What is the recommended way to do this in Bootstrap and CSS? Of course I want it to also look "good" when opened on a phone. The content on top will be rather minimal, so on a small screen, it's unlikely the top and center will touch. This is different from other questions in this style, because I also have some content on the top. I guess I could try to follow one of those answers, and "absolutely" place the content on the top, but somehow this doesn't seem too clean. Are there better solutions?</p>