My 1st Challenge with API

I've tried to put the button fixed so that it do not move whenever I click, but I can't find out that... so I simply put as it is. I also want to know How can I compare my Project just like frontend mentor project comparison above which clearly tells us where we are lacking like in margin, padding, height etc. Any Platform or website where I can compare my Project with the Ideal one before uploading my solution in frontend mentor challenge....