Radius
Dimensions: 0, 2, 4, 8, 16, 24, circle
border radius none
border radius top
border radius right
border radius bottom
border radius left
border radius circle
= .r0
= .rt
= .rr
= .rb
= .rl
= .rc
Around
.r0
.r4
.r8
.r16
.r24
.rc
One side
.rt4
.rr24
.rb16
.rl24
.rtc
.rrc
.rbc
.rlc