LinkedIn Software Engineer - Front-End interview questions

I was contacted by a recruiter on Linkedin. Overall the process was great and everybody I spoke to were nice. Apart from the position , I was mainly concerned about culture and work-life balance and everybody I spoke to were really happy about working there. 1) Technical phone screen - This was a standard collabedit phone screen. Part-1 I was given some code and was asked the output and how to fix it. It was based on scope and JS inheritance. Part-2 HTML/CSS Had to code it from an image they had. I was also asked to explain floats| promises| accessibility.This was pretty straightforward, make sure you brush up on core JS. 2) Heard back roughly a week later and was invited Onsite. The onsite had 6 interviews with lunch. The HR will give you the different modules each interview focuses on. All interviews we mainly focused on UI(html/css/js) except 1 which was an Algo string manipulation question. Some modules were just JS, some I had to build out the whole component as a plugin(html/css/js). The design question was also more UI layer focused than system architecture which was unusual. 3) I left thinking I did well in all my interviews. But unfortunately I didn't get the job, the reason I was given was Design and 1 Js round feedback wasn't good. In both interviews I kept an open dialog discussed solution , improved with hints and reach a agreeable outcome. It was disappointing to not get specific feedback , so I'm not sure what really went wrong.