Typically I am a leader on a team. In my Senior Design project in college I took on the leader role. I think I'm naturally a leader but in this project we didn't have a leader and all were equally contributing / leading our teammates.
Something that helped my group was breaking apart and doing solo research on the technical challenge and coming back together to look out our different options with how to solve.
That you need to agree to disagree. We came across issues that could be solved two different ways and we would disucss which was better but ultimately had to choose. If my approach wasn't choosen I needed to agree to disagree and get on board to keep working on the project.
CSS comes with practice. The more I was working on it the more comfortable I felt with it.
More CSS and working with it. Also refactoring and thinking about different perspectives with refactoring.