Merge pull request #1 from popz73/WCAG-contrast-mistake-button

Mistake button color: WCAG AA compliant contrast

katrain/gui.kv

@@ -236,7 +236,7 @@
             on_press: root.katrain('redo',999)
         NavIconButton:
             icon: 'img/Next-Mistake.png'
-            color: [0.65,0.05,0.05,1]
+            color: [0.93,0.07,0.07,1]
             on_press: root.katrain('next-mistake')
     ClickableLabel:
         pos_hint: {'center_x': 0.85,'center_y':0.5}