Why is the home page like this?

All of a sudden my home page is displaying like I am using mobile browser.
This sudden change has also affected teammate part of the board in bughouse (If you have played bughouse using mobile browsers, this is how it displays).

I have cleared data and cache, I also use Firefox and chrome browser and the result is still the same. Am I the only one seeing this new change? If it is not a bug, please how do I rectify it?

Under the light UI button there will be a button expand

click that

^

Thanks, I found it.

Thanks, I have rectified it.

Once you zoom your screen above 100% (110%) the collapse/Expand button disappears. That's why I haven't been able to find the button for some days now.