layout.scss

// Normalize & Layout
article, aside, details, figcaption, figure, footer,
header, hgroup, nav, section, summary { display: block; }
audio, canvas, video {
  display: inline-block;
  *display: inline;
  *zoom: 1;
  }
audio:not([controls]) { display: none; }
[hidden] { display: none; }

/* Base */
html {
  font-size: 100%;
  -webkit-text-size-adjust: 100%;
  -ms-text-size-adjust: 100%;
  }

@-ms-viewport { width: device-width; }
@-webkit-viewport { width: device-width; }
@-moz-viewport { width: device-width; }
@-o-viewport { width: device-width; }
@viewport { width: device-width; }

html, button, input, select, textarea {
  font-family: sans-serif;
  color: #222;
  }

body {
  margin: 0;
  font-size: 1em;
  line-height: 1.4;
  }

::-moz-selection {
  background: #b3d4fc;
  text-shadow: none;
  }
::selection {
  background: #b3d4fc;
  text-shadow: none;
  }

/* Embedded Content */ 
img {
  border: 0;
  vertical-align: middle;
  -ms-interpolation-mode: bicubic;
  }

svg:not(:root) { overflow: hidden; }

figure { margin: 0; }

/* Form Elements */
form { margin: 0; }
fieldset { border: 0; margin: 0; padding: 0; }
label { cursor: pointer; }
legend {
  border: 0;
  padding: 0;
  white-space: normal;
  *margin-left: -7px;
  }

button, input, select, textarea {
  font-size: 100%;
  margin: 0;
  vertical-align: baseline;
  *vertical-align: middle;
  }
button, input { line-height: normal; }

button, input[type="button"], input[type="reset"], input[type="submit"] {
  cursor: pointer;
  -webkit-appearance: button;
  *overflow: visible;
  }

button[disabled], input[disabled] { cursor: default; }
input[type="checkbox"], input[type="radio"] {
  box-sizing: border-box;
  padding: 0;
  *width: 13px;
  *height: 13px;
  }
button::-moz-focus-inner, input::-moz-focus-inner { border: 0; padding: 0; }

textarea {
  overflow: auto;
  resize: vertical;
  vertical-align: top;
  }

/* Tables */
table { border-collapse: collapse; border-spacing: 0; }
td { vertical-align: top; }

.chromeframe { background: #ccc; color: #000; margin: 0.2em 0; padding: 0.2em 0; }

// Structure

mixins.scss

// Mixins
@mixin retinaBackground($file, $width, $height, $type: png) {
  background-image: url($file + '.' + $type);

  @media (-webkit-min-device-pixel-ratio: 1.5), (-moz-min-device-pixel-ratio: 1.5), (min-resolution: 144dpi) {
    & {
      background-image: url($file + '@2x.' + $type);
      @include background-size($width $height);
    }
  }
}

@mixin size($width, $height) {
  height: $height;
  width: $width;  
}

typography.scss

// Type

// Headings
// --------------------------
h1, h2, h3, h4, h5, h6 {
  margin: ($baseLineHeight / 2) 0;
  font-family: $headingsFontFamily;
  font-weight: $headingsFontWeight;
  line-height: 1;
  color: $headingsColor;
  text-rendering: optimizelegibility; // Fix the character spacing for headings
  small {
    font-weight: normal;
    line-height: 1;
    color: $grayLight;
  }
}
h1 { font-size: 36px; line-height: 40px; }
h2 { font-size: 30px; line-height: 40px; }
h3 { font-size: 24px; line-height: 40px; }
h4 { font-size: 18px; line-height: 20px; }
h5 { font-size: 14px; line-height: 20px; }
h6 { font-size: 12px; line-height: 20px; }

h1 small { font-size: 24px; }
h2 small { font-size: 18px; }
h3 small { font-size: 14px; }
h4 small { font-size: 14px; }

// Links
// --------------------------

a {
  color: #00e;
  @include transition(color 0.25s ease);
  }

a:visited {
  color: #551a8b;
  }

a:hover {
  color: #06e;
  }
a:focus { outline: thin dotted; }
a:hover, a:active { outline: 0; }

// Lists
// --------------------------

ul, ol {
  margin: 1em 0;
  padding: 0 0 0 40px;
  }

dd { margin: 0 0 0 40px; }
nav ul, nav ol {
  list-style: none;
  list-style-image: none;
  margin: 0;
  padding: 0;
  } 


// Misc
// --------------------------

abbr[title] { border-bottom: 1px dotted; }
b, strong { font-weight: bold; }

blockquote { margin: 1em 40px; }

dfn { font-style: italic; }

hr {
  display: block;
  height: 1px;
  border: 0;
  border-top: 1px solid #ccc;
  margin: 1em 0;
  padding: 0;
  }

ins {
  background: #ff9;
  color: #000;
  text-decoration: none;
  }

mark {
  background: #ff0;
  color: #000;
  font-style: italic;
  font-weight: bold;
  }

pre, code, kbd, samp {
  font-family: monospace, serif;
  _font-family: 'courier new', monospace;
  font-size: 1em;
  }

pre {
  white-space: pre;
  white-space: pre-wrap;
  word-wrap: break-word;
  }
q { quotes: none; }
q:before, q:after {
  content: "";
  content: none;
  }

small { font-size: 85%; }

sub, sup {
  font-size: 75%;
  line-height: 0;
  position: relative;
  vertical-align: baseline;
  }
sup { top: -0.5em; }
sub { bottom: -0.25em; }

variables.scss

// Variables

// Grays
// --------------------------
$black:                 #000;
$grayDarker:            #222;
$grayDark:              #333;
$gray:                  #555;
$grayLight:             #999;
$grayLighter:           #eee;
$white:                 #fff;

// Paths
// --------------------------
$imgsPath: "/images";

// Typography
// --------------------------
$sansFontFamily:        "Helvetica Neue", Helvetica, Arial, sans-serif;
$serifFontFamily:       Georgia, "Times New Roman", Times, serif;
$monoFontFamily:        Monaco, Menlo, Consolas, "Courier New", monospace;

$baseFontSize:          14px;
$baseFontFamily:        $sansFontFamily;
$baseLineHeight:        20px;
$altFontFamily:         $serifFontFamily;

$headingsFontFamily:    inherit; // empty to use BS default, $baseFontFamily
$headingsFontWeight:    bold;    // instead of browser default, bold
$headingsColor:         inherit; // empty to use BS default, @textColor