cleanup and response to PR review

lms/static/sass/shared/_footer.scss

@@ -32,16 +32,16 @@
 
     // colophon
     .colophon {
-      margin-right: flex-gutter();
+      @include margin-right(flex-gutter());
       width: flex-grid(8,12);
-      float: left;
+      @include float(left);
 
       .nav-colophon {
         @include clearfix();
         margin: $footer_margin;
 
         li {
-          float: left;
+          @include float(left);
           margin-right: ($baseline*0.75);
 
           a {
@@ -102,12 +102,12 @@
       margin: -2px 0 8px 0;
       font-size: em(11);
       color: $gray-l2;
-      text-align: left;
+      @include text-align(left);
     }
 
     .nav-legal {
       @include clearfix();
-      text-align: left;
+      @include text-align(left);
 
       li {
         display: inline-block;
@@ -154,10 +154,11 @@
 
     // platform Open edX logo and link
     .powered-by {
+      @include float(right);
       width: flex-grid(3,12);
       display: inline-block;
       vertical-align: bottom;
-      text-align: right;
+      @include text-align(right);
 
       a {
         display: inline-block;

lms/static/sass/shared/_header.scss

@@ -146,6 +146,7 @@ header.global {
         @include background-image(url('../images/small-header-home-icon.png'));
         background-repeat: no-repeat;
 
+        // CASE: right to left layout
         @include rtl {
           background-position: top right;
         }
@@ -420,7 +421,7 @@ header.global-new {
       vertical-align: middle;
 
       &:last-child {
-        @include margin-right(0px);
+        @include margin-right(0);
       }
 
       &:hover, &:focus, &:active {
@@ -436,12 +437,12 @@ header.global-new {
     > .primary {
       display: block;
       @include float(left);
-      margin: 0px;
+      margin: 0;
       position: relative;
 
       > a {
         margin: 0px;
-        @include border-right-radius(0px);
+        @include border-right-radius(0);
       }
 
       &:last-child {
@@ -497,7 +498,7 @@ header.global-new {
       display: none;
       padding: 5px 10px;
       position: absolute;
-      @include right(0px);
+      @include right(0);
       top: 34px;
       width: 170px;
       z-index: 3;