Thanks for the report, I'm able to reproduce.  My guess is that the root issue is the same as the one in  https://crbug.com/671722 

When DevTools is run with extreme zoom levels/scale factors, our Console prompt will become cutoff.  CodeMirror tries to account for the height of the scrollbar when calculating the size of the prompt.  In Dark Theme, it looks like we use a different scrollbar style that doesn't scale along with the zoom/scale factor, resulting in a miscalculated console prompt size.

 Issue 805614  has been merged into this issue.

In my case it's more then half so it makes console completely unusable.
OS: Windows 10
Display settings -> Scale: 150%
Display settings -> Resolution: 1920 x 1080
Chrome: 64.0.3282.119

Deleted: chrome-console-bug.png 29.2 KB

	chrome-console-bug.png 29.2 KB View Download

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/36d5b00c49c1adc54accc1e169951cabfda5ddb0

commit 36d5b00c49c1adc54accc1e169951cabfda5ddb0
Author: Erik Luo <luoe@chromium.org>
Date: Mon Jun 04 22:33:16 2018

DevTools: fix dark theme Console prompt cutoff

CodeMirror's 'scroll clipping' process re-measures scrollbars upon zoom to
ensure that its artificial scrollbar is hidden. It assumes that the vertical
scrollbar width is equal to horizontal scrollbar height, which is false.

This CL updates dark theme's custom scrollbar height to be the same as its
width.

Screenshot: https://imgur.com/a/eMUQiIt

Bug:  770633 
Change-Id: Iddfcca8bc48ee414c0307d6d9e4035e2ed8771f9
Reviewed-on: https://chromium-review.googlesource.com/1083595
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Erik Luo <luoe@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564273}
[modify] https://crrev.com/36d5b00c49c1adc54accc1e169951cabfda5ddb0/third_party/blink/renderer/devtools/front_end/ui/inspectorCommon.css

 Issue 849264  has been merged into this issue.

I'm no longer able to reproduce console prompt cutoffs on monitors on light or dark theme in 71.0.3564.0.

In the recent past, a fix landed in CodeMirror [1] and we rolled in changes in for DevTools frontend [2].
[1] https://github.com/codemirror/CodeMirror/issues/5445
[2] https://chromium-review.googlesource.com/c/chromium/src/+/1182680

These fixes should be part of M70 (currently Beta channel) or later.  If anyone still sees a cutoff prompt on M70+, please let us know with a comment with your resolution/flags.

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