Fix(UI): X and ? symbols easier to distinguish in "pure black" dark mode

In addition to that, make "progress ring" a bit more visible.

uhabits-android/src/main/java/org/isoron/uhabits/activities/common/views/RingView.kt

@@ -204,7 +204,7 @@ class RingView : View {
         val res = StyledResources(context)
         if (backgroundColor == null) backgroundColor = res.getColor(R.attr.cardBgColor)
         if (inactiveColor == null) inactiveColor = res.getColor(R.attr.contrast100)
-        inactiveColor = setAlpha(inactiveColor!!, 0.1f)
+        inactiveColor = setAlpha(inactiveColor!!, 0.15f)
         rect = RectF()
     }
 

uhabits-android/src/main/res/values/styles.xml

@@ -126,8 +126,9 @@
         <item name="highlightedBackgroundColor">@color/black</item>
         <item name="contrast0">@color/black</item>
         <item name="contrast20">@color/grey_900</item>
-        <item name="contrast60">@color/grey_700</item>
-        <item name="contrast80">@color/grey_700</item>
+        <item name="contrast40">@color/grey_800</item>
+        <item name="contrast60">@color/grey_500</item>
+        <item name="contrast80">@color/grey_400</item>
         <item name="contrast100">@color/grey_200</item>
         <item name="selectedBackground">@drawable/selected_box</item>
         <item name="textColorAlertDialogListItem">@color/grey_100</item>