Flexbox Nodes within a CSS Flex are inproperly snapping to pixels

Trying to make my first UI in bevy ( version 0.18.0 ).

If you use Display::Flex inside a Display::Grid layout like this:

```
use bevy::{
prelude::*,
};

fn main() {
App::new()
.insert_resource(ClearColor(Color::BLACK))
.add_plugins(DefaultPlugins)
.add_systems(Startup, spawn_layout)
.run();
}

fn spawn_layout(
mut commands: Commands,
) {
commands.spawn(Camera2d);

let rows = [
0.0,
0.2,
0.4,
0.6,
0.8,
1.0,
];

commands.spawn((
Node {
display: Display::Grid,

width: percent(100),
height: percent(100),

grid_template_columns: vec![GridTrack::flex(1.0)],

// This:
grid_template_rows: vec![
GridTrack::flex(1.0),
GridTrack::flex(1.0),
],

..default()
},
BackgroundColor(Color::BLACK),

children![
(
Node { display: Display::Grid, ..default() },
),
(
Node {
display: Display::Grid,

..default()
},

children![
(
Node {
display: Display::Flex,
flex_direction: FlexDirection::Column,

..default()
},

Children::spawn(SpawnIter(
rows.into_iter().map(move |v| node(v)),
)),
),
]
),
],
)
);
}

fn node(u: f32) -> impl Bundle {
let width = 35.0;
let hue = u * 120.0;
let left = Val::Percent( u * (100.0 - width) );
let right = Val::Percent(100.0-(u * (100.0 - width) + width));

(
Node {
width: percent(100),
height: percent(100),

..default()
},
BackgroundColor(Color::hsva(hue, 0.3, 0.3, 0.5)),
children![
(
Node {
position_type: PositionType::Absolute,

left,
right,
top: Val::Percent(0.0),
bottom: Val::Percent(0.0),

..default()
},
BackgroundColor(Color::WHITE.with_alpha(0.15)),

),
]
)
}
```

At some window sizes nodes are misaligned like this:

https://github.com/user-attachments/assets/bb6950a1-4362-49cf-8844-df59de852227

---

```INFO bevy_diagnostic::system_information_diagnostics_plugin::internal: SystemInfo { os: "Windows 10 Pro", kernel: "19045", cpu: "Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz", core_count: "6", memory: "31.8 GiB" }```

```INFO bevy_render::renderer: AdapterInfo { name: "NVIDIA GeForce GTX 1660 Ti", vendor: 4318, device: 8578, device_type: DiscreteGpu, driver: "32.0.15.8180", driver_info: "", backend: Dx12 }```

Start by running the provided Bevy 0.18 example from main, focusing on spawn_layout and node, and resize the window through sizes that reproduce the misalignment. Inspect the UI grid/flex layout and pixel-snapping behavior, then verify that the flexbox child nodes remain aligned across the reported window sizes.

Written by the indexing model from the issue text.