#92: shrink the confirm popup to the window it is in

The card is authored at a fixed 704x1200 around a portrait phone. On a
window wider than it is tall the stretched canvas is about 1080 units high,
so the card sat at y=-60 and hung over both edges - and the confirm and
cancel buttons are anchored to its own bottom edge, so they went off screen
with it. The popup was not merely ugly on a desktop, it was a dead end:
nothing on it could be pressed.

NeonPanel now fits itself to the viewport and re-fits when the window
changes. It only ever shrinks; growing the card would stretch proportions
that are tuned rather than fluid. The fitting adjusts offsets around a
fixed centre, so it applies only to a card pinned to a point - a panel
stretched between different anchors already follows its parent and is left
alone.

Verified across portrait, 16:9, ultrawide and small-laptop shapes, on the
card and on both buttons.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ui/NeonPanel.gd

@@ -7,6 +7,17 @@ extends Control
 # hard-edged neon of the buttons and HUD.
 #
 # Draws itself from its own rect, so it can be sized freely in the scene.
+#
+# #92: it also SHRINKS itself to whatever window it is in. The card is
+# authored at a fixed size around a portrait phone, and on a landscape
+# window - where the canvas is far wider than it is tall - a card taller
+# than the screen simply ran off the top and the bottom, taking the confirm
+# and cancel buttons with it. The buttons are anchored to the panel's own
+# bottom edge, so bringing the edge back on screen brings them back too.
+#
+# Only ever shrinks. Growing the card on a big screen would blow the
+# authored proportions up with it, and the layout inside is tuned, not
+# fluid.
 
 @export var glow_color: Color = Color(0.25, 0.85, 1.0)
 @export var core_color: Color = Color(1.0, 1.0, 1.0)
@@ -15,6 +26,47 @@ extends Control
 @export var fill_color: Color = Color(0.02, 0.03, 0.07, 1.0)
 @export var corner_cut: float = 26.0
 @export var bracket_length: float = 46.0
+# Breathing room kept between the card and the edge of the screen, so a
+# fitted panel reads as a card on a backdrop rather than as a full-bleed
+# page that happens to have a border.
+@export var screen_margin: float = 24.0
+
+# The size the card was authored at, and the point it is centred on. Read
+# once, before any fitting has happened - re-reading them later would
+# measure a previous fit and let the card ratchet smaller on every resize.
+var design_size: Vector2 = Vector2.ZERO
+var design_centre: Vector2 = Vector2.ZERO
+
+
+func _ready() -> void:
+	# Fitting adjusts the four offsets around a fixed centre, which is only
+	# meaningful for a card pinned to a point - both anchor pairs collapsed,
+	# as a centred dialog's are. A panel stretched between different anchors
+	# already follows its parent and is left alone.
+	if not (is_equal_approx(anchor_left, anchor_right) \
+			and is_equal_approx(anchor_top, anchor_bottom)):
+		return
+	design_size = Vector2(offset_right - offset_left, offset_bottom - offset_top)
+	design_centre = Vector2(offset_left + offset_right, offset_top + offset_bottom) * 0.5
+	get_viewport().size_changed.connect(_fit_to_screen)
+	_fit_to_screen()
+
+
+func _fit_to_screen() -> void:
+	if design_size == Vector2.ZERO:
+		return
+	# The viewport rect, not the window: with stretch/mode "canvas_items" the
+	# UI is laid out in stretched canvas units, and those are the units these
+	# offsets are in.
+	var available: Vector2 = get_viewport_rect().size - Vector2(screen_margin, screen_margin) * 2.0
+	var fitted: Vector2 = Vector2(
+		minf(design_size.x, maxf(available.x, 0.0)),
+		minf(design_size.y, maxf(available.y, 0.0)))
+	offset_left = design_centre.x - fitted.x * 0.5
+	offset_right = design_centre.x + fitted.x * 0.5
+	offset_top = design_centre.y - fitted.y * 0.5
+	offset_bottom = design_centre.y + fitted.y * 0.5
+	queue_redraw()
 
 
 func _draw() -> void: