Responsive Advice Generator App Using HTML, CSS, JAVASCRIPT, and API

Hi, this is my first Javascript project and I will love feedback on the following roadblocks:

What I found difficult while building the project? Positioning the click button in the middle. I know i am supposed to use absolute after positioning the main div as relative. However, I found it had placing the image to the middle.

Now, is there a covention on browswer use? I used Chrome and Firefox for the project but I realised they all have different output when it comes to responsiveness. Is there a cheat sheet to build a project that is responsive on all browsers? Kindly give suggestions.

Which area of my code am I u sure of? The responsiveness.

Question about best practices? Like I mentioned above, guideliines on browser responsives.