// extendはsnakecase %box_center

margin: 0 auto

%text_center

text-align: center

%text_bold

font-weight: bold

%clearfix

&:after
  content: ''
  display: block
  clear: both

%reset_default_input

+appearance(none)
+border-radius(0)
background-color: transparent
border: none
padding: 0