This is now tracked on CONF-41035, please follow that issue instead.

Reproduced the problem.

Chrome Canary - Version 51.0.2679.0 canary (64-bit)
Confluence 5.9.5
Windows 7 Pro SP1

Just FYI: I've applied the following styles via Stylish extension for workaround:

#main .edit#content {
    height: calc(100% - 42px);
    width: 100%;
    position: absolute!important;
}

Hope it helps.

updated:

nhoxuan suggested better style:

#content.edit {
    display: table-cell;
}

Ref: CONF-41035

They are aware and currently working on this:
https://bugs.chromium.org/p/chromium/issues/detail?id=346275

I don't think it'll make it into the stable release.

So if the Chrome beta code makes it to production which it most likely will a lot of Confluence users will be affected. Is there a workaround like adding some JavaScript/Css via settings or something to fix this while a code fix is worked out?

We run into the same issue with Confluence 5.9.4.

I'm seeing the same as per issue CONF-41035

This issue has made it into Chrome beta. Reproducible on Version 50.0.2661.26 beta (64-bit)

I also ran into the same issue using the Canary version - Version 50.0.2640.0 canary (64-bit)
But confirmed that it still works on my earlier version of Chrome - my current version is - Version 48.0.2564.97 m (64-bit)
(Same machine - running Windows 10)

Confluence version - 6.0.0-OD-2016.03.1-0006

Hey Daniel,

Thank you for bringing this to our attention.

The version of Chrome you specified is the dev channel, which you can expect to be unstable. For now, you can either switch to the current stable version of Chrome, or the Chrome beta, or try a workaround mentioned in the knowledge base you linked to.

If this bug gets released into a Chrome "Stable" version or even the beta version, we will reopen this ticket or create a new ticket. As Espen pointed out, it looks like they already know about the bug.

Regards,
Jonah Turnquist
Software Engineer, Confluence
Atlassian