Here's a screenshot of the index.html file I've attached which replicated the problem.

Deleted: Screen Shot 2018-01-12 at 6.10.14 PM.png 64.2 KB

	Screen Shot 2018-01-12 at 6.10.14 PM.png 64.2 KB View Download

The example appears to behave the same way in Firefox for me.

The website I was working on originally where I encountered this behavior did not show this bug in FireFox, only in Chrome. However when I made this example I did not test it again in FireFox. And you're right my example is behaving the same in FireFox. But it shouldn't matter if setting explicit widths works like so: 
grid-template-columns: 1fr repeat(2, 300px) 1fr;

Then the max part of minmax() should behave the same way shouldn't it? Right now my workaround is to go inside the container and locate the inner box and set a max-width of 600px which seems redundant.

Tested the issue on Mac 10.12.6 using chrome reported version #63.0.3239.132.

Attached a screen cast for reference.

Following are the steps followed to reproduce the issue.
------------
1. Opened the attached file index.html.
2. Observed a static image which showed the results as in the attached screenshot "Screen Shot 2018-01-12 at 6.10.14 PM.png".

amir@ - Could you please verify the screencast and please let us know if anything else need to be done from our end to reproduce the issue. Any further inputs will help us in triaging the issue further.

Thanks...!!

Deleted: 801725.mp4 524 KB

	801725.mp4 524 KB View Download

This is it! The only other thing would be to resize the screen, it should be responsive and the pinkish container should auto-resize and shrink to fit the browser once the viewport is small enough but this bug is causing it to stay at that expanded width. 

Thank you for providing more feedback. Adding requester "krajshree@chromium.org" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Tested the issue on reported version 63.0.3239.132, on latest canary 65.0.3322.3 and older build M55 using Mac 10.13.1 and below are observations.

In M55 opened added HTML file and resized browser window -- Observed Overflow of green box style="width:800px"

In M63 and M65 observed both pink area and green area stretched. Attaching screencast for reference.

@Reporter: Please check the screencast and let us know if we miss anything. If possible please guide us with expected  behaviour screeshot/screencast. This would help in further triaging of the issue.

Thanks!

On canary 65.0.3323.0 I tested the current behavior and then with some in-browser hacking I was able to show expected behavior as well. 

Basically when you set minmax(auto, 600px) you expect the pink box to shrink with the viewport and be responsive due to min part of minmax() being set to 'auto' and you expect the same box not to grow any larger than 600px because of the max value was explicitly set to '600px'. however it seems like and overflow element can break both min and  max value and neither would work correctly as demonstrated. 

Deleted: minmax.mov 13.6 MB

minmax.mov 13.6 MB Download

Thank you for providing more feedback. Adding requester "sc00335628@techmahindra.com" to the cc list and removing "Needs-Feedback" label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Able to reproduce the issue on reported version 63.0.3239.132 and latest canary 65.0.3323.0 using Mac 10.13.1, Ubuntu 14.04 and Windows-10 hence providing Bisect Info

Bisect Info:
================
Good build: 57.0.2928.0
Bad build: 57.0.2929.0

You are probably looking for a change made after 433852 (known good), but no later than 433853 (first known bad).

https://chromium.googlesource.com/chromium/src/+log/c11607a50691c6da823467bb389d14f659433c77..79bd413143afe5ad68104a3c99b9c04f64fc25ac

Review-Url: https://codereview.chromium.org/2521953002

@rego: Please confirm the issue and help in re-assigning if it is not related to your change.

Thanks!

This is the expected behavior, so this is not a bug.
Imagine you have a column "minmax(auto, 200px)" and it has an element with "width: 400px",
the size of the column is going to be 400px. It'd be something like minmax(400px, 200px),
and min wins over max, like in other places in CSS (min-width and max-width).

See the text in the spec (https://drafts.csswg.org/css-grid/#valdef-grid-template-columns-minmax):
"If max < min, then max is ignored and minmax(min,max) is treated as min."

I believe you could use "grid-template-columns: 1fr repeat(2, minmax(0px, 300px)) 1fr;"
in your example to get the behavior you're looking for.

BTW, some other comments:
* This is working the same in all browsers: Chrome, Firefox, Edge and Safari.
* This is not a regression as it has been working like this since Grid Layout was enabled,
  in the commit pointed in the previous comment.

You are correct, it seems like the proper min value for a container should be 0px rather than auto because according to the spec min can become more than max. I stand corrected, this is not a bug.