あまり見なかったので作った 後で整理する
.ribbon-vertical
w = 46px
size = 3px
position absolute
width (w + size)px
height h = 29px
top t = -(size)px
left 10px
overflow hidden
&::before
position absolute
content ""
width 0
height 0
top t
left (w - size)px
border-width 3px
border-style solid
border-color transparent transparent #333
z-index 1
&::after
position absolute
display block
text-align center
content "New"
color #FFF
background #ccc
width w
height h
line-height h
z-index 10
top 0
left 0