input-placeholder.sass

// Mixins ---------------------------------------------------------------

=placeholder
  &::-webkit-input-placeholder
    @children
  &:-moz-placeholder
    @children
  &.placeholder 
    @children

=my-placeholder
  +placeholder
    color: #777
    // add your defaults here.

// if you need more than type you can create several mixins,
=another-kind-of-placeholder
  +placeholder
    color: red

// Template --------------------------------------------------------------
// you can create as many templates as you need for your site

.placeholders
  +my-placeholder

// Placeholders --------------------------------------------------------------
// call the template with @extend when you can
// or, when fighting the cascade you can call the mixin

input, textarea
  @extend .placeholders

.something
  +another-kind-of-placeholder