I’ve something strange since upgrading to 0.91.1. My hass.io runs on a VM and I use a combination of web browsers (OSX, Raspbian, IOS) and apps to access Home Assistant.
Since upgrading to 0.91.1 (and now 0.91.4) when viewing the overview:
On OSX and Chrome - All appears in one large screen with no tabs in regular mode
On OSX and Chrome in incognito - All appears as normal with separate tabs and items
On OSX and Safari - All appears and normal
On Raspbian and Chromium - All appears as configured with separate tabs and items
On IOS devices using the app - Same as Chromium, all works
I’ve tried clearing the cache, deleting extensions, etc. No luck with chrome.
You could be looking at the ipaddress/states/default_view web page instead of the ipaddress/lovelace/default_view web page for the one with everything on one page.
Check your links / bookmmarks. Also check the development tools info panel and make sure the big button above the system health box is set to lovelace as default for the browser that is showing everything on one page.