title: PyQt5 button background color not taking effect
body: <p>Here is the button's code:</p>
  
  <pre><code>    self.pushButton.setFont(font)
      self.pushButton.setStyleSheet("background-color: qlineargradient(spread:pad, x1:0.0568182, y1:0.126, x2:0.75, y2:0.227, stop:0.0738636 rgba(0, 255, 0, 255), stop:0.840909 rgba(0, 136, 0, 255));\n")
      self.pushButton.setFlat(True)
      self.pushButton.setObjectName("pushButton")
  </code></pre>
  
  <p>Although I set a background gradient to this button, it's not taking effect.</p>
  
  <p>Here's the button normally:</p>
  
  <p><a href="https://i.stack.imgur.com/CcJLq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/CcJLq.png" alt="enter image description here"></a></p>
  
  <p>Here's when it's pressed down:</p>
  
  <p><a href="https://i.stack.imgur.com/bIupf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bIupf.png" alt="enter image description here"></a></p>