There's a white box over my screen, so I can't see full window.
The zoom settings of the browser needs to be checked. Ensure that the value is not something bigger than 100%
To solve this, press CTRL + 0 (that's Zero key) on your keyboard while your browser is open. This should set the zoom back to 100%.
Here is a video replicating the issue
If at 100% you are still not seeing your page and page contents (big white box) on the right, please try to make your screen even smaller - say 60%.