A CodePen by joshgreen. Simple CSS3 button

index.haml

%div.wrap
  %a{ :href => "http://www.mozilla.com/en-US/firefox/" }  Get firefox

style.sass

@import "compass"
*
  +box-sizing(border-box)

body
  background-color: #f2f2f2
  padding: 10%

.wrap
  margin: 0 auto
  text-align: center
  font-family: Lato, Helvetica Neue, sans-serif

a
  text-decoration: none
  position: relative
  font-weight: bold
  font-size: 1.6em
  +background-image(linear-gradient(rgba(254,218,113,1),rgba(254,190,77,1)))
  +border-radius(0.2em)
  padding: 0.5em 1em
  color: rgba(153,102,51,1)
  text-shadow: 0 2px 3px rgba(255,255,255,0.5)
  +box-shadow(rgba(185,138,55, 1) 0 5px 0, rgba(159,118,48, .1) 0 6px 1px, rgba(white, 1) 0 1px 0 inset)
  +transition-property(all)
  +transition-duration(0.5s) 
  border: 2px solid rgba(234,181,81,1) 
  &:hover
    +background-image(linear-gradient(rgba(254,190,77,1),rgba(254,218,113,1)))
  &:active
    +box-shadow(none)
    top: 5px