Font-Awesome/scss/_core.scss

/* FONT AWESOME CORE
 * -------------------------- */

.#{$fa-css-prefix} {
  display: inline-block;
  font-family: FontAwesome;
  font-style: normal;
  font-weight: normal;
  line-height: 1;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* makes the font 33% larger relative to the icon container */
.#{$fa-css-prefix}-lg {
  font-size: (4em / 3);
  line-height: (3em / 4);
  vertical-align: -15%;
}

.#{$fa-css-prefix}-fixed-width {
 width: (18em / 14);
 text-align: center;
}


// Icon UL & LI
// -------------------------

.#{$fa-css-prefix}-ul {
  padding-left: 0;
  margin-left: $fa-icon-li-width;
  list-style-type: none;

  > li { position: relative; }
}
.#{$fa-css-prefix}-li {
  position: absolute;
  left: -$fa-icon-li-width;
  width: $fa-icon-li-width;
  top: (2em / 14);
  text-align: center;
  &.#{$fa-css-prefix}-lg {
    left: -$fa-icon-li-width + (4em / 14);
  }
}


// allows usage of the hide class directly on font awesome icons
.#{$fa-css-prefix}.hide { display: none; }

.#{$fa-css-prefix}-muted { color: $fa-icon-muted; }
.#{$fa-css-prefix}-light { color: $fa-icon-light; }
.#{$fa-css-prefix}-dark { color: $fa-icon-dark; }


// Icon Borders
// -------------------------

.#{$fa-css-prefix}-border {
  padding: .2em .25em .15em;
  border: solid 1px $fa-border-color;
  border-radius: 3px;
}


// Icon Sizes
// -------------------------

.#{$fa-css-prefix}-2x {
  font-size: 2em;
  &.#{$fa-css-prefix}-border {
    border-width: 2px;
    border-radius: 4px;
  }
}
.#{$fa-css-prefix}-3x {
  font-size: 3em;
  &.#{$fa-css-prefix}-border {
    border-width: 3px;
    border-radius: 5px;
  }
}
.#{$fa-css-prefix}-4x {
  font-size: 4em;
  &.#{$fa-css-prefix}-border {
    border-width: 4px;
    border-radius: 6px;
  }
}
.#{$fa-css-prefix}-5x {
  font-size: 5em;
  &.#{$fa-css-prefix}-border {
    border-width: 5px;
    border-radius: 7px;
  }
}


// Floats & Margins
// -------------------------

// Quick floats
.pull-right { float: right; }
.pull-left { float: left; }

.#{$fa-css-prefix} {
  &.pull-left { margin-right: .3em; }
  &.pull-right { margin-left: .3em; }
}