ltk: responsive padding/spacing and scrolling, expanded theme palette, and bundled Adwaita cursors

A mixed pass over the default theme and the layout/input core, plus the toolkit's own cursor set. Grouped by area below.
== Responsive sizing ==
Add `Length::dp( px )` — a "design pixel". It interprets `px` against a configurable reference vmin (default 412 px, the eydos mobile reference width) and returns `Vmin( px / reference * 100 ).clamp( px * 0.7, px * 1.5 )`, so a value authored against a mock-up scales with the surface without collapsing on tiny screens or ballooning on a 4K desktop. The reference is process-global, set via `set_design_reference()` and read via `design_reference()` (stored as f32 bits in an AtomicU32); both are re-exported from `lib.rs`.
Make container and grid insets relative. `Container`'s four padding fields become `Length` instead of `f32`; every setter (`padding`, `padding_h`, `padding_v`, `padding_top`/`right`/`bottom`/`left`) now takes `impl Into<Length>`, so existing `f32` call sites keep compiling via the `From<f32>` shim. The values are resolved against the viewport in `Container::preferred_size` and in the container draw path (`draw/layout.rs`). `WrapGrid`'s `spacing_x`, `spacing_y` and `padding` get the same treatment, with a `resolved( canvas )` helper funnelling the per-frame resolution and `grid()` seeding `Length::px` defaults. Container tests now compare against `Length::px( … )`.
== Scrolling ==
`Scroll::preferred_size` is now axis-aware. A horizontal-only scroll reports its child's natural height rather than claiming all remaining vertical space, so it no longer steals Y from its siblings when it sits inside a `Column`; vertical and both-axis scrolls keep the spacer-like `( max_width, 0.0 )`. `Column`'s space-distribution correspondingly treats a `Scroll` as a vertical space-claimer only when its axis allows Y.
Disambiguate nested scroll viewports by direction. On press the gesture state now collects every scroll viewport under the point (`scroll_candidates`, innermost first) instead of committing to one; on the first 8 px of motion it locks onto the candidate whose axis matches the dominant direction (`scroll_locked`), so a horizontal scroller nested inside a vertical list no longer grabs the wrong axis. The pointer scroll hit test is aligned to the same innermost-first ordering.
== Theme palette ==
`themes/default/theme.json` gains named colours (green / green-deep, yellow, orange / orange-deep, pink / pink-soft, sky-deep, error / error-soft, neutral-tertiary) and new semantic slots in both light and dark modes: `danger`, `text-tertiary`, `accept`, `chip` / `chip-active` / `chip-active-fg`, and `avatar-1` … `avatar-9`.
== Cursors ==
Bundle GNOME's Adwaita cursor theme — the cursors GNOME Shell uses — into `themes/default/cursors/` so a Wayland compositor can draw consistent, complete pointers for ltk applications without the toolkit rasterising cursors itself and without depending on adwaita-icon-theme being installed on the target. The cursors are copied verbatim in XCursor binary format: 35 image files, one per CSS/freedesktop cursor name (default, text, pointer, *-resize, …), plus 27 customary X11 alias symlinks (arrow → default, hand2 → pointer, …); a sibling `cursor.theme` makes the tree a valid XCursor theme. The existing `ltk-theme-default.install` copies `themes/default` recursively, so the directory ships with no packaging change. Applications keep declaring a `CursorShape` per widget over `wp_cursor_shape_v1`; the compositor resolves it against the active theme's `cursors/` directory by name, and the set covers all 34 `CursorShape` variants.
Document the set in `themes/default/cursors/README.md` (what it is, the XCursor layout, the full shape list, how the compositor consumes it, guidance for forks) and `themes/default/cursors/LICENSE.md` (attribution and licence options, modelled on the icons catalogue LICENSE). `lib.rs` lists the cursors in its third-party-assets section.
Close out licensing in `debian/copyright`: a `Files: themes/default/cursors/*` paragraph records the upstream dual offer (CC-BY-SA-3.0 or LGPL-3, and CC-BY-SA-4.0 for the newer assets) attributed to the GNOME Project, with standalone CC-BY-SA-3.0, CC-BY-SA-4.0 and LGPL-3 paragraphs (summary-plus-canonical-URL for the CC licences, matching the existing CC-BY-4.0 entry; LGPL-3 referencing /usr/share/common-licenses/LGPL-3). The files are unmodified from upstream, so there is nothing to declare under the ShareAlike "indicate if changes were made" clause.
Add `tests/cursor_assets.rs`: every `CursorShape` name resolves to a valid XCursor file (Xcur magic, following symlinks), `cursor.theme` is present, no entry is a dangling symlink, and the expected-name list stays in sync with the enum's 34 variants.

src/draw/layout.rs

@@ -195,12 +195,18 @@ pub( crate ) fn layout_and_draw<Msg: Clone>(
 			{
 				canvas.stroke_rect( rect, color, width, c.corners );
 			}
+			let vp = canvas.viewport_logical();
+			let em = crate::types::Length::EM_BASE_DEFAULT;
+			let pad_l = c.pad_left.resolve(   vp, em );
+			let pad_r = c.pad_right.resolve(  vp, em );
+			let pad_t = c.pad_top.resolve(    vp, em );
+			let pad_b = c.pad_bottom.resolve( vp, em );
 			let inner = crate::types::Rect
 			{
-				x:      rect.x + c.pad_left,
-				y:      rect.y + c.pad_top,
-				width:  ( rect.width  - c.pad_left - c.pad_right  ).max( 0.0 ),
-				height: ( rect.height - c.pad_top  - c.pad_bottom ).max( 0.0 ),
+				x:      rect.x + pad_l,
+				y:      rect.y + pad_t,
+				width:  ( rect.width  - pad_l - pad_r ).max( 0.0 ),
+				height: ( rect.height - pad_t - pad_b ).max( 0.0 ),
 			};
 			let result = layout_and_draw::<Msg>( c.child.as_ref(), canvas, inner, ctx, flat_idx );
 

src/input/gesture/mod.rs

@@ -68,6 +68,10 @@ pub struct GestureState<Msg: Clone>
 	/// Index of the Scroll viewport that owns the current gesture, if
 	/// the press landed inside one.
 	pub scrolling_widget:        Option<( usize, crate::widget::scroll::ScrollAxis )>,
+	/// Scroll viewports containing the press, innermost first.
+	pub scroll_candidates:       Vec<( usize, crate::widget::scroll::ScrollAxis )>,
+	/// `true` once the first 8 px of motion has pinned `scrolling_widget` to a definite axis.
+	pub scroll_locked:           bool,
 	/// Scroll-viewport drag exceeded the 8 px start tolerance — the
 	/// release will be consumed as a scroll instead of a tap.
 	pub scroll_drag_started:     bool,
@@ -136,6 +140,8 @@ impl<Msg: Clone> GestureState<Msg>
 			start:                   None,
 			pressed_idx:             None,
 			scrolling_widget:        None,
+			scroll_candidates:       Vec::new(),
+			scroll_locked:           false,
 			scroll_drag_started:     false,
 			horizontal_drag_started: false,
 			vertical_drag_started:   false,
@@ -175,9 +181,12 @@ impl<Msg: Clone> GestureState<Msg>
 		}).unwrap_or( ( None, None ) );
 
 		self.start                   = Some( pos );
-		self.scrolling_widget        = scroll_rects.iter().rev()
-			.find( |( r, _, _ )| r.contains( pos ) )
-			.map( |( _, idx, ax )| ( *idx, *ax ) );
+		self.scroll_candidates       = scroll_rects.iter()
+			.filter( |( r, _, _ )| r.contains( pos ) )
+			.map( |( _, idx, ax )| ( *idx, *ax ) )
+			.collect();
+		self.scrolling_widget        = self.scroll_candidates.first().copied();
+		self.scroll_locked           = false;
 		self.scroll_drag_started     = false;
 		self.horizontal_drag_started = false;
 		self.vertical_drag_started   = false;
@@ -289,19 +298,30 @@ impl<Msg: Clone> GestureState<Msg>
 			return MoveOutcome::Idle;
 		}
 
-		// Scroll viewport drag: mutate offset in place and advance the
-		// gesture origin so the next delta is frame-to-frame, not
-		// press-to-now (otherwise the first 8 px trip the threshold
-		// and the entire scroll gets absorbed into one delta). Both
-		// axes are routed independently; an axis the viewport does not
-		// allow is just ignored (delta still consumed by the gesture,
-		// so the swipe handler does not fight the scroll for it).
-		if let Some( ( scroll_idx, axis ) ) = self.scrolling_widget
+		if self.scrolling_widget.is_some()
 		{
 			if let Some( start ) = self.start
 			{
-				let dx    = pos.x - start.x;
-				let dy    = pos.y - start.y;
+				let dx = pos.x - start.x;
+				let dy = pos.y - start.y;
+
+				if !self.scroll_locked
+				{
+					if dx.abs() <= 8.0 && dy.abs() <= 8.0
+					{
+						return MoveOutcome::Idle;
+					}
+					let prefer_x = dx.abs() > dy.abs();
+					if let Some( c ) = self.scroll_candidates.iter()
+						.find( |( _, ax )| if prefer_x { ax.allows_x() } else { ax.allows_y() } )
+						.copied()
+					{
+						self.scrolling_widget = Some( c );
+					}
+					self.scroll_locked = true;
+				}
+
+				let ( scroll_idx, axis ) = self.scrolling_widget.unwrap();
 				let entry = scroll_offsets.entry( scroll_idx ).or_insert( ( 0.0, 0.0 ) );
 				if axis.allows_x() { entry.0 = ( entry.0 - dx ).max( 0.0 ); }
 				if axis.allows_y() { entry.1 = ( entry.1 - dy ).max( 0.0 ); }

src/input/pointer/scroll.rs

@@ -33,7 +33,7 @@ impl<A: App> AppData<A>
 		let scroll_hit =
 		{
 			let ss = self.surface( focus );
-			ss.scroll_rects.iter().rev()
+			ss.scroll_rects.iter()
 				.find( |( r, _, _ )| r.contains( pos ) )
 				.map( |( _, idx, ax )| ( *idx, *ax ) )
 		};

src/layout/column.rs

@@ -224,21 +224,19 @@ impl<Msg: Clone> Column<Msg>
 		let pad     = self.resolved_padding( canvas );
 		let spacing = self.resolved_spacing( canvas );
 
-		// Flexible spacers and Scroll widgets claim remaining vertical space.
-		// Fixed-height spacers behave like normal fixed-size children.
 		let total_weight: u32 = self.children.iter()
 			.map( |c| match c
 			{
 				Element::Spacer( s ) if s.resolved_height( canvas ).is_none() => s.weight,
-				Element::Scroll( _ ) => 1,
-				_                    => 0,
+				Element::Scroll( s ) if s.axis.allows_y() => 1,
+				_                                          => 0,
 			} )
 			.sum();
 
 		let fixed_h: f32 = self.children.iter()
 			.map( |c|
 			{
-				if matches!( c, Element::Scroll( _ ) )
+				if matches!( c, Element::Scroll( s ) if s.axis.allows_y() )
 				{
 					0.0
 				} else if let Element::Spacer( s ) = c {
@@ -282,7 +280,7 @@ impl<Msg: Clone> Column<Msg>
 					};
 					( inner_w, h )
 				},
-				Element::Scroll( _ ) =>
+				Element::Scroll( s ) if s.axis.allows_y() =>
 				{
 					let h = if total_weight > 0
 					{

src/layout/wrap_grid.rs

@@ -2,7 +2,7 @@
 // Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>
 
 use crate::render::Canvas;
-use crate::types::Rect;
+use crate::types::{ Length, Rect };
 use crate::widget::Element;
 
 /// A grid layout that wraps children into rows of a fixed column count.
@@ -35,12 +35,12 @@ pub struct WrapGrid<Msg: Clone>
 	pub children:        Vec<Element<Msg>>,
 	/// Number of columns per row.
 	pub columns:         usize,
-	/// Horizontal gap between cells (pixels).
-	pub spacing_x:       f32,
-	/// Vertical gap between rows (pixels).
-	pub spacing_y:       f32,
-	/// Padding on all sides (pixels).
-	pub padding:         f32,
+	/// Horizontal gap between cells.
+	pub spacing_x:       Length,
+	/// Vertical gap between rows.
+	pub spacing_y:       Length,
+	/// Padding on all sides.
+	pub padding:         Length,
 	/// When `true`, a partial last row is centred horizontally within
 	/// the grid's content rect instead of being left-aligned.
 	pub centre_last_row: bool,
@@ -56,31 +56,32 @@ impl<Msg: Clone> WrapGrid<Msg>
 	}
 
 	/// Set both horizontal and vertical gap between cells (default 8.0).
-	pub fn spacing( mut self, s: f32 ) -> Self
+	pub fn spacing( mut self, s: impl Into<Length> ) -> Self
 	{
+		let s = s.into();
 		self.spacing_x = s;
 		self.spacing_y = s;
 		self
 	}
 
 	/// Set only the horizontal gap between cells; leaves vertical spacing untouched.
-	pub fn spacing_x( mut self, s: f32 ) -> Self
+	pub fn spacing_x( mut self, s: impl Into<Length> ) -> Self
 	{
-		self.spacing_x = s;
+		self.spacing_x = s.into();
 		self
 	}
 
 	/// Set only the vertical gap between rows; leaves horizontal spacing untouched.
-	pub fn spacing_y( mut self, s: f32 ) -> Self
+	pub fn spacing_y( mut self, s: impl Into<Length> ) -> Self
 	{
-		self.spacing_y = s;
+		self.spacing_y = s.into();
 		self
 	}
 
 	/// Set the padding on all sides (default 0.0).
-	pub fn padding( mut self, p: f32 ) -> Self
+	pub fn padding( mut self, p: impl Into<Length> ) -> Self
 	{
-		self.padding = p;
+		self.padding = p.into();
 		self
 	}
 
@@ -92,6 +93,17 @@ impl<Msg: Clone> WrapGrid<Msg>
 		self
 	}
 
+	fn resolved( &self, canvas: &Canvas ) -> ( f32, f32, f32 )
+	{
+		let vp = canvas.viewport_logical();
+		let em = Length::EM_BASE_DEFAULT;
+		(
+			self.spacing_x.resolve( vp, em ),
+			self.spacing_y.resolve( vp, em ),
+			self.padding.resolve(   vp, em ),
+		)
+	}
+
 	/// Compute the preferred size given an available width.
 	pub fn preferred_size( &self, max_width: f32, canvas: &Canvas ) -> (f32, f32)
 	{
@@ -99,12 +111,13 @@ impl<Msg: Clone> WrapGrid<Msg>
 		{
 			return ( max_width, 0.0 );
 		}
+		let ( sx, sy, pad ) = self.resolved( canvas );
 		let cols      = self.columns;
-		let inner_w   = (max_width - self.padding * 2.0).max( 0.0 );
-		let cell_w    = (inner_w - self.spacing_x * (cols as f32 - 1.0)).max( 0.0 ) / cols as f32;
+		let inner_w   = (max_width - pad * 2.0).max( 0.0 );
+		let cell_w    = (inner_w - sx * (cols as f32 - 1.0)).max( 0.0 ) / cols as f32;
 		let row_count = (self.children.len() + cols - 1) / cols;
 
-		let mut total_h = self.padding * 2.0;
+		let mut total_h = pad * 2.0;
 		for row in 0..row_count
 		{
 			let start = row * cols;
@@ -114,7 +127,7 @@ impl<Msg: Clone> WrapGrid<Msg>
 				.map( |c| c.preferred_size( cell_w, canvas ).1 )
 				.fold( 0.0_f32, f32::max );
 			total_h += row_h;
-			if row + 1 < row_count { total_h += self.spacing_y; }
+			if row + 1 < row_count { total_h += sy; }
 		}
 		( max_width, total_h )
 	}
@@ -126,11 +139,12 @@ impl<Msg: Clone> WrapGrid<Msg>
 		{
 			return Vec::new();
 		}
+		let ( sx, sy, pad ) = self.resolved( canvas );
 		let cols    = self.columns;
-		let inner_w = (rect.width - self.padding * 2.0).max( 0.0 );
-		let cell_w  = (inner_w - self.spacing_x * (cols as f32 - 1.0)).max( 0.0 ) / cols as f32;
-		let x0      = rect.x + self.padding;
-		let mut y   = rect.y + self.padding;
+		let inner_w = (rect.width - pad * 2.0).max( 0.0 );
+		let cell_w  = (inner_w - sx * (cols as f32 - 1.0)).max( 0.0 ) / cols as f32;
+		let x0      = rect.x + pad;
+		let mut y   = rect.y + pad;
 
 		let row_count = (self.children.len() + cols - 1) / cols;
 		let mut out   = Vec::with_capacity( self.children.len() );
@@ -148,16 +162,16 @@ impl<Msg: Clone> WrapGrid<Msg>
 			let row_offset   = if self.centre_last_row && items_in_row < cols
 			{
 				let missing = (cols - items_in_row) as f32;
-				missing * (cell_w + self.spacing_x) / 2.0
+				missing * (cell_w + sx) / 2.0
 			} else { 0.0 };
 
 			for col in 0..items_in_row
 			{
-				let x    = x0 + row_offset + col as f32 * (cell_w + self.spacing_x);
+				let x    = x0 + row_offset + col as f32 * (cell_w + sx);
 				let crect = Rect { x, y, width: cell_w, height: row_h };
 				out.push( ( crect, start + col ) );
 			}
-			y += row_h + self.spacing_y;
+			y += row_h + sy;
 		}
 		out
 	}
@@ -396,9 +410,9 @@ pub fn grid<Msg: Clone>( columns: usize ) -> WrapGrid<Msg>
 	{
 		children:        Vec::new(),
 		columns,
-		spacing_x:       8.0,
-		spacing_y:       8.0,
-		padding:         0.0,
+		spacing_x:       Length::px( 8.0 ),
+		spacing_y:       Length::px( 8.0 ),
+		padding:         Length::px( 0.0 ),
 		centre_last_row: false,
 	}
 }

src/lib.rs

@@ -159,6 +159,16 @@
 //! - **Sora Regular** (`src/theme/fallback/Sora-Regular.otf`) — the
 //!   embedded font fallback, [SIL OFL 1.1](https://scripts.sil.org/OFL),
 //!   © The Sora Project Authors, Jonathan Barnbrook, Julián Moncada.
+//! - **Pointer cursors** under `themes/default/cursors/` — GNOME's
+//!   *Adwaita* cursor theme (the cursors GNOME Shell ships), bundled
+//!   verbatim, © the GNOME Project. Offered upstream under
+//!   [CC BY-SA 3.0](https://creativecommons.org/licenses/by-sa/3.0/) *or*
+//!   [LGPL 3](https://www.gnu.org/licenses/lgpl-3.0.html), and
+//!   [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/) for
+//!   the newer assets; any one option satisfies the licence. See
+//!   `themes/default/cursors/README.md` (what the set is and how it is
+//!   used) and `themes/default/cursors/LICENSE.md` (attribution).
+//!   Upstream: <https://gitlab.gnome.org/GNOME/adwaita-icon-theme>.
 //!
 //! The remaining artwork in the default theme (wallpapers, lockscreens,
 //! launcher logo, brand-mark variants, per-application icons) is
@@ -230,6 +240,7 @@ pub use gles_render::{ BorrowedGlesTexture, GlesVersion };
 pub use render::is_software_render;
 pub use wallpaper::{ WallpaperBundle, ImageData };
 pub use types::{ Color, Corners, CursorShape, Length, LengthBase, Point, Rect, Size, WidgetId };
+pub use types::{ design_reference, set_design_reference };
 pub use widget::{ Element, button, icon_button, text_edit, image as img_widget, text, container };
 pub use widget::button::ButtonVariant;
 pub use widget::slider::{ Slider, slider, SliderAxis };

src/types.rs

@@ -24,6 +24,8 @@
 //! `ltk::Rect`, …) so application code rarely needs the `ltk::types::`
 //! prefix.
 
+use std::sync::atomic::{ AtomicU32, Ordering };
+
 /// An RGBA color with floating-point channels in the range `[0.0, 1.0]`.
 #[ derive( Debug, Clone, Copy, PartialEq ) ]
 pub struct Color
@@ -524,6 +526,17 @@ impl Length
 	pub const fn vmax( v: f32 ) -> Self { Self::from_base( LengthBase::Vmax( v ) ) }
 	pub const fn em(   v: f32 ) -> Self { Self::from_base( LengthBase::Em(   v ) ) }
 
+	/// "Design pixel": `px` interpreted at the reference vmin set via
+	/// [`set_design_reference`] (defaults to 412 px — the eydos mobile
+	/// reference width). The result is a `Vmin` value clamped to
+	/// `[px * 0.7, px * 1.5]`, so the layout scales with the screen
+	/// without collapsing on tiny surfaces or ballooning on 4K.
+	pub fn dp( px: f32 ) -> Self
+	{
+		let r = design_reference();
+		Length::vmin( px / r * 100.0 ).clamp( px * 0.7, px * 1.5 )
+	}
+
 	/// Resolve to a concrete logical-pixel value given a viewport and an
 	/// `em_base` (the root font size that `Em` is a fraction of).
 	pub fn resolve( &self, viewport: ( f32, f32 ), em_base: f32 ) -> f32
@@ -573,6 +586,23 @@ impl Length
 	}
 }
 
+static DESIGN_REFERENCE_BITS: AtomicU32 = AtomicU32::new( 412.0_f32.to_bits() );
+
+/// Set the reference vmin width that [`Length::dp`] interprets `px` against.
+/// Call once at startup (e.g. before [`crate::run`]) to align the design
+/// scale to the surface mock-up the app was designed for.
+pub fn set_design_reference( reference_vmin: f32 )
+{
+	DESIGN_REFERENCE_BITS.store( reference_vmin.to_bits(), Ordering::Relaxed );
+}
+
+/// Current value used by [`Length::dp`] — the px width at which `dp(n)`
+/// resolves to `n` logical pixels.
+pub fn design_reference() -> f32
+{
+	f32::from_bits( DESIGN_REFERENCE_BITS.load( Ordering::Relaxed ) )
+}
+
 impl From<f32> for Length
 {
 	fn from( v: f32 ) -> Self { Length::px( v ) }

src/widget/container/mod.rs

@@ -2,7 +2,7 @@
 // Copyright (C) 2026 Liberux Labs, S. L. <info@liberux.net>
 
 use crate::theme::Paint;
-use crate::types::{ Color, Corners };
+use crate::types::{ Color, Corners, Length };
 use crate::render::Canvas;
 use super::Element;
 
@@ -72,15 +72,16 @@ pub struct Container<Msg: Clone>
 	/// left edge, …) without hitting the renderer with an offset
 	/// trick.
 	pub corners:    Corners,
-	/// Padding on the top edge in logical px — gap between the
-	/// container's top boundary and its child.
-	pub pad_top:    f32,
-	/// Padding on the right edge in logical px.
-	pub pad_right:  f32,
-	/// Padding on the bottom edge in logical px.
-	pub pad_bottom: f32,
-	/// Padding on the left edge in logical px.
-	pub pad_left:   f32,
+	/// Padding on the top edge — gap between the container's top boundary
+	/// and its child. Stored as a [`Length`] so it can scale with the
+	/// viewport via [`Length::dp`] / [`Length::vmin`].
+	pub pad_top:    Length,
+	/// Padding on the right edge.
+	pub pad_right:  Length,
+	/// Padding on the bottom edge.
+	pub pad_bottom: Length,
+	/// Padding on the left edge.
+	pub pad_left:   Length,
 	pub opacity:    f32,
 	/// Optional `( color, width_px )` border stroke painted around the
 	/// container's rounded rectangle, after the fill / surface and
@@ -109,10 +110,10 @@ impl<Msg: Clone> Container<Msg>
 			background: None,
 			surface:    None,
 			corners:    Corners::ZERO,
-			pad_top:    0.0,
-			pad_right:  0.0,
-			pad_bottom: 0.0,
-			pad_left:   0.0,
+			pad_top:    Length::px( 0.0 ),
+			pad_right:  Length::px( 0.0 ),
+			pad_bottom: Length::px( 0.0 ),
+			pad_left:   Length::px( 0.0 ),
 			opacity:    1.0,
 			border:     None,
 			max_width:  None,
@@ -197,8 +198,9 @@ impl<Msg: Clone> Container<Msg>
 	/// edges, so calling this first and then a per-edge setter is the
 	/// idiomatic way to express "uniform padding except for one
 	/// edge".
-	pub fn padding( mut self, p: f32 ) -> Self
+	pub fn padding( mut self, p: impl Into<Length> ) -> Self
 	{
+		let p = p.into();
 		self.pad_top    = p;
 		self.pad_right  = p;
 		self.pad_bottom = p;
@@ -207,16 +209,18 @@ impl<Msg: Clone> Container<Msg>
 	}
 
 	/// Set horizontal padding (left + right each).
-	pub fn padding_h( mut self, p: f32 ) -> Self
+	pub fn padding_h( mut self, p: impl Into<Length> ) -> Self
 	{
+		let p = p.into();
 		self.pad_left  = p;
 		self.pad_right = p;
 		self
 	}
 
 	/// Set vertical padding (top + bottom each).
-	pub fn padding_v( mut self, p: f32 ) -> Self
+	pub fn padding_v( mut self, p: impl Into<Length> ) -> Self
 	{
+		let p = p.into();
 		self.pad_top    = p;
 		self.pad_bottom = p;
 		self
@@ -225,30 +229,30 @@ impl<Msg: Clone> Container<Msg>
 	/// Set the top edge padding only. Pairs with
 	/// [`padding_bottom`](Self::padding_bottom) for asymmetric
 	/// vertical insets.
-	pub fn padding_top( mut self, p: f32 ) -> Self
+	pub fn padding_top( mut self, p: impl Into<Length> ) -> Self
 	{
-		self.pad_top = p;
+		self.pad_top = p.into();
 		self
 	}
 
 	/// Set the right edge padding only.
-	pub fn padding_right( mut self, p: f32 ) -> Self
+	pub fn padding_right( mut self, p: impl Into<Length> ) -> Self
 	{
-		self.pad_right = p;
+		self.pad_right = p.into();
 		self
 	}
 
 	/// Set the bottom edge padding only.
-	pub fn padding_bottom( mut self, p: f32 ) -> Self
+	pub fn padding_bottom( mut self, p: impl Into<Length> ) -> Self
 	{
-		self.pad_bottom = p;
+		self.pad_bottom = p.into();
 		self
 	}
 
 	/// Set the left edge padding only.
-	pub fn padding_left( mut self, p: f32 ) -> Self
+	pub fn padding_left( mut self, p: impl Into<Length> ) -> Self
 	{
-		self.pad_left = p;
+		self.pad_left = p.into();
 		self
 	}
 
@@ -271,9 +275,15 @@ impl<Msg: Clone> Container<Msg>
 	/// Return the preferred `(width, height)` accounting for padding.
 	pub fn preferred_size( &self, max_width: f32, canvas: &Canvas ) -> ( f32, f32 )
 	{
+		let vp = canvas.viewport_logical();
+		let em = Length::EM_BASE_DEFAULT;
+		let pad_l = self.pad_left.resolve(   vp, em );
+		let pad_r = self.pad_right.resolve(  vp, em );
+		let pad_t = self.pad_top.resolve(    vp, em );
+		let pad_b = self.pad_bottom.resolve( vp, em );
 		let avail = self.max_width.map( |m| max_width.min( m ) ).unwrap_or( max_width );
-		let pad_x = self.pad_left + self.pad_right;
-		let pad_y = self.pad_top  + self.pad_bottom;
+		let pad_x = pad_l + pad_r;
+		let pad_y = pad_t + pad_b;
 		let inner_w = ( avail - pad_x ).max( 0.0 );
 		let ( cw, ch ) = self.child.preferred_size( inner_w, canvas );
 		( cw + pad_x, ch + pad_y )

src/widget/container/tests.rs

@@ -3,6 +3,7 @@
 
 use super::*;
 use crate::layout::spacer::spacer;
+use crate::types::Length;
 
 #[ test ]
 fn default_no_background()
@@ -15,30 +16,30 @@ fn default_no_background()
 fn padding_sets_all_four_sides()
 {
 	let c = container::<()>( spacer() ).padding( 10.0 );
-	assert_eq!( c.pad_top,    10.0 );
-	assert_eq!( c.pad_right,  10.0 );
-	assert_eq!( c.pad_bottom, 10.0 );
-	assert_eq!( c.pad_left,   10.0 );
+	assert_eq!( c.pad_top,    Length::px( 10.0 ) );
+	assert_eq!( c.pad_right,  Length::px( 10.0 ) );
+	assert_eq!( c.pad_bottom, Length::px( 10.0 ) );
+	assert_eq!( c.pad_left,   Length::px( 10.0 ) );
 }
 
 #[ test ]
 fn padding_h_only_touches_left_and_right()
 {
 	let c = container::<()>( spacer() ).padding_h( 8.0 );
-	assert_eq!( c.pad_left,  8.0 );
-	assert_eq!( c.pad_right, 8.0 );
-	assert_eq!( c.pad_top,    0.0 );
-	assert_eq!( c.pad_bottom, 0.0 );
+	assert_eq!( c.pad_left,  Length::px( 8.0 ) );
+	assert_eq!( c.pad_right, Length::px( 8.0 ) );
+	assert_eq!( c.pad_top,    Length::px( 0.0 ) );
+	assert_eq!( c.pad_bottom, Length::px( 0.0 ) );
 }
 
 #[ test ]
 fn padding_v_only_touches_top_and_bottom()
 {
 	let c = container::<()>( spacer() ).padding_v( 6.0 );
-	assert_eq!( c.pad_top,    6.0 );
-	assert_eq!( c.pad_bottom, 6.0 );
-	assert_eq!( c.pad_left,  0.0 );
-	assert_eq!( c.pad_right, 0.0 );
+	assert_eq!( c.pad_top,    Length::px( 6.0 ) );
+	assert_eq!( c.pad_bottom, Length::px( 6.0 ) );
+	assert_eq!( c.pad_left,  Length::px( 0.0 ) );
+	assert_eq!( c.pad_right, Length::px( 0.0 ) );
 }
 
 #[ test ]
@@ -48,10 +49,10 @@ fn per_edge_overrides_uniform_padding()
 	let c = container::<()>( spacer() )
 		.padding( 12.0 )
 		.padding_bottom( 22.0 );
-	assert_eq!( c.pad_top,    12.0 );
-	assert_eq!( c.pad_right,  12.0 );
-	assert_eq!( c.pad_bottom, 22.0 );
-	assert_eq!( c.pad_left,   12.0 );
+	assert_eq!( c.pad_top,    Length::px( 12.0 ) );
+	assert_eq!( c.pad_right,  Length::px( 12.0 ) );
+	assert_eq!( c.pad_bottom, Length::px( 22.0 ) );
+	assert_eq!( c.pad_left,   Length::px( 12.0 ) );
 }
 
 #[ test ]

src/widget/scroll/mod.rs

@@ -93,13 +93,27 @@ impl<Msg: Clone> Scroll<Msg>
 		self
 	}
 
-	/// Returns `(max_width, 0.0)` — the Scroll node claims all remaining space in
-	/// the parent layout, exactly like a [`Spacer`](crate::layout::spacer::Spacer).
-	/// The actual viewport size is determined at render time from the rect the
-	/// parent assigns.
-	pub fn preferred_size( &self, max_width: f32, _canvas: &Canvas ) -> (f32, f32)
+	/// Preferred size — axis-aware.
+	///
+	/// - **Vertical or both**: returns `(max_width, 0.0)`. The Scroll node
+	///   claims all remaining space in the parent layout, exactly like a
+	///   [`Spacer`](crate::layout::spacer::Spacer). The actual viewport size
+	///   is determined at render time from the rect the parent assigns.
+	/// - **Horizontal-only**: claims `max_width` but reports the child's
+	///   natural height. A horizontal scroll has an intrinsic height (the
+	///   row of items it clips) and must not steal Y space from its siblings
+	///   when it sits inside a [`Column`](crate::layout::column::Column).
+	pub fn preferred_size( &self, max_width: f32, canvas: &Canvas ) -> (f32, f32)
 	{
-		( max_width, 0.0 )
+		match self.axis
+		{
+			ScrollAxis::Horizontal =>
+			{
+				let ( _, h ) = self.child.preferred_size( max_width, canvas );
+				( max_width, h )
+			}
+			ScrollAxis::Vertical | ScrollAxis::Both => ( max_width, 0.0 ),
+		}
 	}
 
 	/// No-op — rendering is handled entirely by `layout_and_draw` in `draw.rs`.