How can I maintain html and css typography ?

I saw many themes which was rejected for less typography , but how can I maintain typography …

however, if my body is font-size, color, line-height, link transition,font-weight like

body {font-size:16px;line-height:28px;color:red;},
a { transition:all .3s ease-in-out} ,

can I over use font-size, color, line-height, link transition,font-weight … when Paragraph, Anger tag is same like body font-size such as p {font-size:16px;line-height:28px; color:red}

how many color can I give my theme ?

overall , Can I used again and again …