Pretty old huh? But I still find it funny

This is so me. I've been doing some frontend at work and feel so lost.
Luckily the frontend guys are good at QA.

Front end developer with a pixel perfect manager.

I thought everybody did frontend the way I do it:
1. guess a random number for width/height that sounds right
2. F5
3. look at it for 30 seconds
4. make another guess, hopefully a bit closer to what you want to achieve
5. repeat from step 2. until it looks ok