app/assets/stylesheets/application/components/_mutable_content.css.sass
@import compass/css3/opacity
@import compass/css3/transition
@import compass/css3/transform
// transparent blocks that opacify on ancestor hover
.af-mutable-content
.af-mutable
+transition-property(opacity)
+transition-duration(250ms)
+opacity(0.10)
+translateZ(0.0)
.af-dim
+opacity(0.33)
&:hover, &.focused
.af-mutable
+opacity(1.00)