Many color theme were messed, the split bars can not be seen

Type: Bug

After upgraded from 1.131.0 to 1.135.0, with `workbench.experimental.modernUI` default to `true`, the split bars between blocks in side panel can not be seen. I tried many color themes, some were right but many of them have this problem. I'm using "Tomorrow Night Blue".

VS Code version: Code 1.135.0 (08d4889f9ec4a1685d257b9b95de036c8e1ce1e5, 2026-08-25T14:26:52Z)
OS version: Windows_NT x64 10.0.19045
Modes:

System Info

|Item|Value|
|---|---|
|CPUs|AMD Ryzen 7 5800H with Radeon Graphics (16 x 3194)|
|GPU Status|2d_canvas: enabled
GPU0: VENDOR= 0x10de, DEVICE=0x24dd [NVIDIA GeForce RTX 3070 Laptop GPU], DRIVER_VENDOR=NVIDIA, DRIVER_VERSION=32.0.15.6636 *ACTIVE*
GPU1: VENDOR= 0x10de, DEVICE=0x24dd [NVIDIA GeForce RTX 3070 Laptop GPU], DRIVER_VERSION=32.0.15.6636
GPU2: VENDOR= 0x10de, DEVICE=0x24dd [NVIDIA GeForce RTX 3070 Laptop GPU], DRIVER_VERSION=32.0.15.6636
GPU3: VENDOR= 0x1414, DEVICE=0x008c [Microsoft Basic Render Driver], DRIVER_VERSION=10.0.19041.5794
Machine model name:
Machine model version:
direct_rendering_display_compositor: disabled_off_ok
gpu_compositing: enabled
multiple_raster_threads: enabled_on
opengl: enabled_on
rasterization: enabled
raw_draw: disabled_off_ok
skia_graphite: disabled_off
trees_in_viz: disabled_off
video_decode: enabled
video_encode: enabled
webgl: enabled
webgpu: enabled
webnn: disabled_off|
|Load (avg)|undefined|
|Memory (System)|15.86GB (6.79GB free)|
|Process Argv|--crash-reporter-id 3da377c1-fa3a-43b8-8876-0c7281c06c65|
|Screen Reader|no|
|VM|0%|
Extensions (30)

Name|Identifier|Author|Version
---|---|---|---
Better Comments|aaron-bond.better-comments|aaron-bond|3.0.2
GitHub Markdown Preview|bierner.github-markdown-preview|bierner|0.4.0
Markdown Emoji|bierner.markdown-emoji|bierner|0.3.1
Markdown Footnotes|bierner.markdown-footnotes|bierner|0.1.1
Markdown Preview Github Styling|bierner.markdown-preview-github-styles|bierner|2.2.0
Ruff|charliermarsh.ruff|charliermarsh|2026.68.0
Python Environment Manager (deprecated)|donjayamanne.python-environment-manager|donjayamanne|1.2.7
Markdown Table Formatter|fcrespo82.markdown-table-formatter|fcrespo82|3.0.0
Todo Tree|gruntfuggly.todo-tree|Gruntfuggly|0.0.226
Edit CSV|janisdd.vscode-edit-csv|janisdd|0.11.9
Python Indent|kevinrose.vsc-python-indent|KevinRose|1.21.0
Rainbow CSV|mechatroner.rainbow-csv|mechatroner|3.24.1
Monokai Pro|monokai.theme-monokai-pro-vscode|monokai|2.0.13
Python Debugger|ms-python.debugpy|ms-python|2026.6.0
Python|ms-python.python|ms-python|2026.4.0
Pylance|ms-python.vscode-pylance|ms-python|2026.3.1
Data Wrangler|ms-toolsai.datawrangler|ms-toolsai|1.24.2
Jupyter|ms-toolsai.jupyter|ms-toolsai|2025.9.1
Jupyter Keymap|ms-toolsai.jupyter-keymap|ms-toolsai|1.1.2
Jupyter Notebook Renderers|ms-toolsai.jupyter-renderers|ms-toolsai|1.3.0
Jupyter Cell Tags|ms-toolsai.vscode-jupyter-cell-tags|ms-toolsai|0.1.9
Jupyter Slide Show|ms-toolsai.vscode-jupyter-slideshow|ms-toolsai|0.1.6
Hex Editor|ms-vscode.hexeditor|ms-vscode|1.11.1
Gremlins tracker for Visual Studio Code|nhoizey.gremlins|nhoizey|0.26.0
autoDocstring - Python Docstring Generator|njpwerner.autodocstring|njpwerner|0.6.1
Python Type Hint|njqdev.vscode-python-typehint|njqdev|1.5.1
indent-rainbow|oderwat.indent-rainbow|oderwat|8.3.1
Markdown Preview Enhanced|shd101wyy.markdown-preview-enhanced|shd101wyy|0.8.30
Salesforce XML Formatter|swagup.sf-xml-formatter|SwagUp|0.0.3
Markdown All in One|yzhang.markdown-all-in-one|yzhang|3.6.3

A/B Experiments

```
vsliv368:30146709
binariesv615:30325510
nativeloc1:31344060
dwcopilot:31170013
dwoutputs:31242946
copilot_t_ci:31333650
e5gg6876:31282496
pythonrdcb7:31342333
6518g693:31463988
aj953862:31281341
envsactivate1:31551504
cloudbuttont:31379625
3efgi100_wstrepl:31403338
55ia6109:31457054
ec5jj548:31422691
cp_cls_t_966_ss:31526232
4je02754:31466945
8hhj4413:31478653
cp_cls_c_1081:31454833
conptydll_true:31498968
e9c30283:31461165
46204921:31447328
ei9d7968:31496641
chat:31457767
ddid_t:31478206
hmra_i5g22:31518061
7df3h592:31512476
cp_cls_t_1082:31535311
logging_enabled_new:31498466
j0d79568:31499440
jb_cp_cls_t_632:31543129
56dj4588:31512888
32d76977:31512328
ha629193:31508444
a1ije391_t:31540920
jbcp_cls_pctr_t:31531130
61138546:31518536
cp_intellij_t_nes:31548657
d7b18187:31526828
ahp-both-windows:31556933
hjji5903:31534458
f412h606:31551416
7g2b5551:31542111
enable_editor_pane_layout:31569726
allow-none:31555437
36h42362:31564511
c7c27ce7:31554789
1h923230:31564177
1532g621_copy:31554320
treatment-23-1:31555779
unuse_dynamic_mcp:31555281
0d8dfbc3:31570291
0c1h4866:31566224
session-archive:31558132
5b8j3302:31564601
mangle-name-treatment:31572634
lunaclean:31573760
multiv2:31574985
permission_prompt_treatment:1332566
ccr_pr_nudge_adoption:1319471
vsc_wsm_t:1340632
eh853263:1355661
h5e14506:1348996

```