UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.88 Safari/537.36

Steps to reproduce the problem:
Note: issue reproduces only on some devices (see below for details)
1. Go to http://output.jsbin.com/qiweqal/4/ (source code: http://jsbin.com/qiweqal/4/edit?html,css,output) or attached example
2. Play with widow width

What is the expected behavior?
No vertical lines should appear

What went wrong?
Vertical lines appear

Did this work before? Yes 63 (not sure) on Mac, 65 beta on Windows (details below)

Does this work in other browsers? Yes

Chrome version: 66.0.3356.0  Channel: canary
OS Version: 10.0
Flash Version: 

We initially encountered this problem on Chrome stable on Mac, later we also noticed it on Canary on Windows. Due to the fact that they look similarly I'm reporting it as one but they may have different causes.

In the original app we see both vertical and horizontal lines, when creating reduced test case we somehow lost horizontal ones.

Mac:
Video: https://drive.google.com/file/d/1F6au9R8kVLWlcr4o12_L5vv0g05mm_MU/view
We confirmed it on Chrome Stable on two iMacs: 27-inch Mid 2011, AMD Radeon HD 6770M 512 MB and Late 2015, 27-inch, Retina 5K, AMD Radeon R9 M380 2 GB. We tested it on few Macbooks with both integrated GPU and Nvidia dGPU without success.
Running with --disable-gpu solves the problem (tested on Mid 2011 iMac).

Bisection result (run on Mid 2011 iMac):
You are probably looking for a change made after 511575 (known good), but no later than 511594 (first known bad).
CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/6cb050470520e652eeb894fd01f87ca6a2d6034a..9cf0ac139cc65890b9e036f704040c8da332d6e3

Windows:
Video: https://drive.google.com/file/d/1JuDABF5NxIIsdny61pihPY-21FyrGz1b/view
Confirmed on PC with ATI Radeon HD 4800 Series GPU and Sony Vaio VGN-FW11M notebook (ATI Mobility Radeon HD 3470).
Also tested on PC with Nvidia GeForce GTX 1080 without success.
Running with --disable-gpu does *not* fix the problem (tested on PC).

Bisection result (run on PC):
You are probably looking for a change made after 530655 (known good), but no later than 530678 (first known bad).
CHANGELOG URL:
https://chromium.googlesource.com/chromium/src/+log/a23805be7cc445a07a96a235706e509b6c298647..ddbc46dff7954067faa1da9afba766446752a8c4
 

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