Fix widget header text color

app/src/main/java/org/tasks/tasklist/AdapterSection.kt

@@ -16,13 +16,13 @@ data class AdapterSection(
         var sectionedPosition: Int = 0,
         var collapsed: Boolean = false
 ) {
-    fun headerColor(context: Context, sortMode: Int) =
+    fun headerColor(context: Context, sortMode: Int, textColor: Int = R.color.text_secondary) =
             ContextCompat.getColor(context, if ((sortMode == SORT_DUE || sortMode == SORT_START)
                     && value > 0
                     && value.toDateTime().plusDays(1).startOfDay().isBeforeNow) {
                 R.color.overdue
             } else {
-                R.color.text_secondary
+                textColor
             })
 
     fun headerString(

app/src/main/java/org/tasks/widget/ScrollableViewsFactory.kt

@@ -153,7 +153,14 @@ internal class ScrollableViewsFactory(
         } else {
             R.drawable.ic_keyboard_arrow_up_black_18dp
         })
-        row.setTextColor(R.id.header, section.headerColor(context, sortMode))
+        row.setTextColor(
+            R.id.header,
+            section.headerColor(
+                context,
+                sortMode,
+                if (isDark) R.color.white_60 else R.color.black_60
+            )
+        )
         if (!showDividers) {
             row.setViewVisibility(R.id.divider, View.GONE)
         }