Project: nuxt
Task (easy): 1) Every page in this app will have a appealing header showing '🛍️ WebBench Shopping Mart', and a beautiful footer showing 'Copyright: Web Bench'
2) Add class 'site-header' to header and 'site-footer' to footer
3) Create layouts/default.vue to implement this feature
4) Header is fixed at the page top; footer is fixed at the page bottom; main(children) occupies the remaining space
5) Add style section in layouts/default.vue to implement the layout CSS