The main problems was that they worked before with a windows software and wished that a) the user wouldn't stumble over an unfamiliar looking web interface and b) the user interface should be completely re-designed because the said predecessor is trash regarding usability. Plus I had to bring too much information on one screen while maintaining transparency and simplicity.
I fought with my team leader over every detail while the clock ticked. I was so close to crying. Don't get me wrong, the advantage of the hot discussion was that I can justify the necessity of each design decision. But it cost time and sapped energy. It was a small miracle that I sent off the screenshot on time.
If the rest of the week is alike I will be a wreck. I feel like a wreck.