Content
1
2
width / height
width: 50%
width: 100px
border
solid
dashed
dotted
border-bottom
border: 1px solid black;
border-bottom: 5px solid green;
border-radius
10px
50%
outline
outline: 2px solid red;
box-sizing: border-box
content-box (width: 200px)
border-box
(width: 200px)