feat(aio): add original style for feature page

fixes link to quick start; moves $unit to constants

aio/content/marketing/features.html

@@ -58,7 +58,7 @@
       </div>
     </div>
   </div>
-  <div class="cta-bar"><a href="/docs/ts/latest/quickstart.html" md-button="md-button"
+  <div class="cta-bar"><a href="guide/quickstart" md-button="md-button"
                           class="button button-large button-shield mat-raised mat-primary">Get
     Started</a></div>
 </article>

aio/src/styles/2-modules/_contributor.scss

@@ -1,4 +1,3 @@
-$unit: 8px;
 $metal: #536E7A;
 $snow: #FFFFFF;
 $steel: #253238;

aio/src/styles/2-modules/_features.scss

@@ -0,0 +1,24 @@
+.feature-row {
+  display: flex;
+  justify-content: space-between;
+  flex-wrap: wrap;
+
+  @media (max-width: 600px) {
+    flex-direction: column;
+  }
+
+  h2.text-headline {
+    font-size: 28px;
+    margin-top: 10px;
+    color: #37474F;
+  }
+}
+
+.features-desc {
+  max-width: 920px;
+}
+
+.feature {
+  max-width: 350px;
+  margin-bottom: $unit * 4;
+}

aio/src/styles/2-modules/_modules-dir.scss

@@ -3,6 +3,7 @@
    ============================== */
 
    @import 'hamburger';
+   @import 'features';
    @import 'code';
    @import 'contributor';
    @import 'alert';

aio/src/styles/2-modules/_presskit.scss

@@ -1,4 +1,3 @@
-$unit: 8px;
 .presskit-container {
   h2 {
     color: #37474F;

aio/src/styles/_constants.scss

@@ -1,4 +1,5 @@
 $small-breakpoint-width: 840px;
+$unit: 8px;
 
 // TYPOGRAPHY
 $main-font: "Roboto","Helvetica Neue Light","Helvetica Neue",Helvetica,Arial,"Lucida Grande",sans-serif;