So.. I got my evisa issued today, also in time as they promised (Sunday application day, then after two days I got it).
Since many people write about issues with photos I would like to share how I did it.
I took my Samsung Galaxy S7, stood in front of a white wall (in my room), took a selfie with the front camera of the phone (vertical), making sure my head was big enough and somewhat in the center, then I sent the photo to my email address. I sat down, opened the email on the computer, downloaded the photo, realized that the file size is too large and went to www.tinypng.com
to drag and drop the photo and make it much smaller. Then I saved the compressed photo locally and uploaded it when asked on the evisa page. And it worked perfectly fine right away.
I did not care about resolution, about dpi number, about size/ proportion of the photo etc. It seems normal vertical mobile phone size of photo is good enough.
Good luck everybody!