Stick scroll blends into editor contents with high contrast theme

[mjbvz]

Type: Bug

1. Enable stick scroll
2. Switch to high contrast
3. Scroll down in a file

Bug
There is no contrast between the stick scroll content and the normal editor content:

Related #157185

VS Code version: Code - Insiders 1.75.0-insider (Universal) (07d6f5b, 2023-01-26T05:22:17.192Z)
OS version: Darwin x64 22.2.0
Modes:
Sandboxed: Yes

System Info

Item	Value
CPUs	Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz (16 x 2400)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: disabled_off direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled metal: disabled_off multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_renderer: enabled_on video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: disabled_off
Load (avg)	2, 2, 2
Memory (System)	32.00GB (0.02GB free)
Process Argv	--crash-reporter-id 48781ca2-1705-4f64-9bab-325055aab55d
Screen Reader	no
VM	0%

[aiday-mar]

For verification:

1. Enable sticky scroll, switch to high-contrast and scroll down the file.
2. You should see a border on the bottom of the sticky scroll widget

[bpasero]

I see it in dark theme but not light high contrast: