diff --git a/Bedtime/Bedtime/Constants.swift b/Bedtime/Bedtime/Constants.swift
index 358a686..529362e 100644
--- a/Bedtime/Bedtime/Constants.swift
+++ b/Bedtime/Bedtime/Constants.swift
@@ -61,4 +61,10 @@ class Constants {
     static func sleepDurationColor(hours: Double, goal: Double, graceColor: Color) -> Color {
         sleepGoalColor(difference: hours - goal, graceColor: graceColor)
     }
+
+    /// Named coordinate space for the app's main scroll view. Descendants can measure their
+    /// position relative to it (`.named(mainScrollCoordinateSpaceName)`) to reliably track how
+    /// far they are from the top/bottom of the visible viewport as the user scrolls—unlike
+    /// `.global` frames, which don't update consistently during interactive scrolling.
+    static let mainScrollCoordinateSpaceName = "mainScrollView"
 }
diff --git a/Bedtime/Bedtime/ContentView.swift b/Bedtime/Bedtime/ContentView.swift
index c3044d4..4f756d6 100644
--- a/Bedtime/Bedtime/ContentView.swift
+++ b/Bedtime/Bedtime/ContentView.swift
@@ -18,6 +18,7 @@ struct ContentView: View {
     @State private var showingSettings = false
     @State private var showingError = false
     @State private var error: Error?
+    @State private var scrollViewportSize: CGSize = .zero
     
     init() {
         let sourcePrefs = SourcePreferences()
@@ -187,6 +188,13 @@ struct ContentView: View {
                 .frame(maxWidth: 600)
                 .frame(maxWidth: .infinity)
             }
+            .coordinateSpace(name: Constants.mainScrollCoordinateSpaceName)
+            .onGeometryChange(for: CGSize.self) { proxy in
+                proxy.size
+            } action: { _, newValue in
+                scrollViewportSize = newValue
+            }
+            .environment(\.scrollViewportSize, scrollViewportSize)
             .environment(\.durationDisplayStyle, userPreferences.durationDisplayStyle)
             .background(Color.backgroundBehindCards)
             .navigationTitle("Bedger")
diff --git a/Bedtime/Bedtime/Views/SleepBankCard.swift b/Bedtime/Bedtime/Views/SleepBankCard.swift
index 034daa1..212c236 100644
--- a/Bedtime/Bedtime/Views/SleepBankCard.swift
+++ b/Bedtime/Bedtime/Views/SleepBankCard.swift
@@ -7,6 +7,20 @@
 
 import SwiftUI
 
+private struct ScrollViewportSizeKey: EnvironmentKey {
+    static let defaultValue: CGSize = .zero
+}
+
+extension EnvironmentValues {
+    /// Size of the main scroll view's viewport, published by `ContentView` via
+    /// `onGeometryChange`. Lets a card reason about how much room is above/below it on
+    /// screen without relying on `.global` frames, which don't track reliably during scroll.
+    var scrollViewportSize: CGSize {
+        get { self[ScrollViewportSizeKey.self] }
+        set { self[ScrollViewportSizeKey.self] = newValue }
+    }
+}
+
 struct SleepBankCard: View {
     /// Balance over the selected range, which the Average / Status / Goal columns report.
     let sleepBank: SleepBank
@@ -17,8 +31,18 @@ struct SleepBankCard: View {
     /// When provided, the goal is tappable and edits this value directly.
     var sleepGoalHours: Binding<Double>? = nil
     @Environment(\.durationDisplayStyle) private var durationStyle
+    @Environment(\.scrollViewportSize) private var scrollViewportSize
 
     @State private var isEditingGoal = false
+    /// The goal button's frame relative to the main scroll view's viewport, kept up to date
+    /// by `onGeometryChange` (including while the user is actively scrolling).
+    @State private var goalButtonFrame: CGRect = .zero
+
+    /// Rough on-screen height of the goal popover's wheel picker plus its popover chrome,
+    /// used to decide whether there's enough room above the button to open upward. The wheel
+    /// picker itself is a fixed system height (~190pt even after the editor's negative
+    /// padding), so this pads that out a bit for the popover's own arrow/margins.
+    private static let goalPopoverEstimatedHeight: CGFloat = 210
 
     private var formattedGoal: String {
         TimeFormatter.formatHours(
@@ -125,7 +149,15 @@ struct SleepBankCard: View {
             .accessibilityLabel("Sleep goal")
             .accessibilityValue(formattedGoal)
             .accessibilityHint("Adjusts your nightly sleep goal")
-            .popover(isPresented: $isEditingGoal, arrowEdge: .bottom) {
+            .onGeometryChange(for: CGRect.self) { proxy in
+                proxy.frame(in: .named(Constants.mainScrollCoordinateSpaceName))
+            } action: { _, newValue in
+                goalButtonFrame = newValue
+            }
+            // Prefers opening above (arrowEdge .bottom) so it never covers the chart below,
+            // falling back to opening below only when there truly isn't room above—e.g. when
+            // this card is scrolled near the very top of the screen.
+            .popover(isPresented: $isEditingGoal, arrowEdge: goalPopoverArrowEdge) {
                 SleepGoalEditor(goalHours: sleepGoalHours)
                     .frame(maxWidth: 150)
                     .presentationCompactAdaptation(.popover)
@@ -135,6 +167,18 @@ struct SleepBankCard: View {
         }
     }
 
+    private var goalPopoverArrowEdge: Edge {
+        guard scrollViewportSize != .zero, goalButtonFrame != .zero else { return .bottom }
+
+        let spaceAbove = goalButtonFrame.minY
+        let spaceBelow = scrollViewportSize.height - goalButtonFrame.maxY
+
+        if spaceAbove < Self.goalPopoverEstimatedHeight && spaceBelow > spaceAbove {
+            return .top
+        }
+        return .bottom
+    }
+
     private func goalLabel(showsEditAffordance: Bool) -> some View {
         VStack(alignment: .trailing, spacing: 2) {
             Text("Goal")
@@ -169,6 +213,7 @@ private struct SleepBankCardPreview: View {
 
     @State private var days = 7
     @State private var goalHours = 8.0
+    @State private var scrollViewportSize: CGSize = .zero
 
     private var allNights: [NightSummary] {
         let calendar = Calendar.current
@@ -204,6 +249,13 @@ private struct SleepBankCardPreview: View {
             )
             .padding()
         }
+        .coordinateSpace(name: Constants.mainScrollCoordinateSpaceName)
+        .onGeometryChange(for: CGSize.self) { proxy in
+            proxy.size
+        } action: { _, newValue in
+            scrollViewportSize = newValue
+        }
+        .environment(\.scrollViewportSize, scrollViewportSize)
         .background(Color.backgroundBehindCards)
     }
 }