UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Example URL:
(see included sample code)

Steps to reproduce the problem:
1. Place attached files into the same directory/folder
2. Test can be run using local host or actual server
3. Navigate to "testParent.html" using Chrome v53
4. Press the various buttons to see visual abnormalities appear (Buttons are: 'Load All', 'Load #0', 'Load #1', 'Load #2')

What is the expected behavior?
The expected result is that each iframe (and the parent) contain a heading with green background and purple monospace text, followed by a series of red shapes (circle, square and triangle).  All instances of the HTML file being displayed make reference to the same three CSS files in order to acquire this specific styling: background.css, fonts.css and shapes.css.

What went wrong?
The results you will see using Chrome version 53.0.2785.116 is that at various times one or more of the pages being displayed will appear differently than expected.  Its as if at times one or more of the pages will ignore or lose track of its link to one or more of the external stylesheets.

Does it occur on multiple sites: N/A

Is it a problem with a plugin? No 

Did this work before? Yes Any Chrome version before v53

Does this work in other browsers? Yes 

Chrome version: 53.0.2785.116  Channel: stable
OS Version: 6.1 (Windows 7, Windows Server 2008 R2)
Flash Version: Shockwave Flash 23.0 r0

Please let me know if there is something I am doing wrong in my use of external spreadsheets or any other feedback you could provide.
 

Deleted: testParent.html 2.9 KB

testParent.html 2.9 KB View Download

Deleted: testChild.html 1011 bytes

testChild.html 1011 bytes View Download

Deleted: background.css 393 bytes

background.css 393 bytes View Download

Deleted: fonts.css 410 bytes

fonts.css 410 bytes View Download

Deleted: shapes.css 795 bytes

shapes.css 795 bytes View Download