what is the default for box-sizing
the default is box-content. It is usually better to set that to box-border so when we set hight and width we set it to include content+padding+border and not just the content
list-style:none
remove the bullets of the ul/ol
calc
allows us to do calculation on properties
display:inline-block
makes an element inline but allows us to work with padding margin left/right
padding: 10px 10px
shorthand for top/buttom left/right