title: Changed background colors of action bar and pages after update to .forms 3.1
body: <p>I’m on the way to update my <strong>.forms (shared)</strong> project: </p>
  
  <ul>
  <li>VS2015 Update 3 RC -> VS2017 15.7.5</li>
  <li>.forms 2.3.0.49 -> <strong>.forms 3.1</strong></li>
  </ul>
  
  <p><strong>Important note: I don’t use XAML yet (I do anything in code).</strong></p>
  
  <p>First I have compiled the “old” project without to update forms -> the colors were identical to the compile with .forms 2.3.0 under VS2015.<br>
  Then I have updated the whole project to forms 3.1 (without any further change in the settings / code).<br>
  After that, the colors were changed automatically so that the app becomes unusable.<br>
  In the <strong>old</strong> version (.forms 2.3.0):  </p>
  
  <ul>
  <li><p>The background color of the action (title) bar was white and the 
  title text color was black</p></li>
  <li><p>The page back colors were black (therefore I have set the text colors to white and light green, what was good readable on the black background)</p></li>
  </ul>
  
  <p>In the <strong>new</strong> version (.forms 3.1)</p>
  
  <ul>
  <li>The background color of the action (title) bar is black and the title
  text color also (still is) black (not readable / usable) </li>
  <li>The page back colors is white are white and the text color still is white and light green (not readable / usable)</li>
  </ul>
  
  <p>Also further colors (e.g. to the edit control) were changed in a bad way (old: dark grey background and white text color, new: dark gray background and black text color).</p>
  
  <p>So... something has changed between .forms 2.3.0 and .forms 3.1 - maybe some setting / file is missing in my project to the base color settings...?</p>
  
  <p>As I don’t want to change the colors to any used objects in my app, I search for a way to “restore” the color settings with .forms 3.1 like it was in 2.3.0 but don’t have found any useful information’s yet (trying for day’s now).  </p>
  
  <p>Does anybody knows, why this happens and what I have to do to set the "old" base background colors for the whole app?</p>