title: How to set Font size or Label size to fit all device
body: <p>How to set kivy font size or label size so that it will fit all phone-device screen? (fit by means does not overlap with the boundary, rectangle, or even the screen)</p>
  
  <p>I know the Buttons and some other Widgets in Kivy have <code>size_hint</code>. This <code>size_hint</code> does not give desired result. </p>
  
  <p>Also, setting the <code>font_size</code> can do the trick, but it will be difficult to automate using this. Now close solution is by setting and getting the <code>Window.size</code> in <em>cm</em>, and use <code>font_size</code> in <em>cm</em>. </p>
  
  <p>Thanks in advance.</p>