[Vuejs]-How should I organise vue.js components in a reasonable way?

Use <style scoped> to namespace the elements you want namespaced. I work on a pretty complex app written in Vue and when I need to style lots of elements that are shared by many components, I either include unscoped styles in the parent components, or I use scss or css modules in ./src/scss/ to style those shared elements. That way, you get to take advantage of Vue’s scoped styles, but also create more reusable styles if you need.