Fix sticky header when headerMinHeight is set lower than safeAreaInsets.top

Merge pull request #25 from dusiema/bufgix24

Author: danielsaidi

Sources/ScrollKit/ScrollViewWithStickyHeader.swift

@@ -99,14 +99,14 @@ private extension ScrollViewWithStickyHeader {
 
     var isStickyHeaderVisible: Bool {
         guard let headerMinHeight else { return headerVisibleRatio <= 0 }
-        return scrollOffset.y < -headerMinHeight
+        return scrollOffset.y < -(headerHeight - headerMinHeight)
     }
 
     @ViewBuilder
     var navbarOverlay: some View {
         if isStickyHeaderVisible {
             Color.clear
-                .frame(height: navigationBarHeight)
+                .frame(height: headerMinHeight != nil ? nil : navigationBarHeight)
                 .overlay(scrollHeader, alignment: .bottom)
                 .ignoresSafeArea(edges: .top)
                 .frame(height: headerMinHeight)