tidy up, add base responsive nav, update readme

assets/styles/config/_mixins.scss

@@ -1,60 +1,56 @@
 /*
  * Media query to respond to a minimum size (mobile first)
  */
-
 @mixin resp-min($size) {
-    @media screen and (min-width: $size) { 
-        @content; 
-    }
+  @media screen and (min-width: $size) {
+    @content;
+  }
 }
 
 
 /*
  * Media query to respond to a maximum size
  */
-
 @mixin resp-max($size) {
-    @media screen and (max-width: $size) { 
-        @content; 
-    }
+  @media screen and (max-width: $size) {
+    @content;
+  }
 }
 
 
 /*
  * Output font size in px/rem
  */
-
 @mixin font-size($px) {
-    font-size: $px + px;
-    font-size: #{$px / 16}rem;
+  font-size: $px + px;
+  font-size: #{$px / 16}rem;
 }
 
 
 /*
  * Placeholder mixin for <input>
  */
-
 @mixin placeholder {
-    $placeholders: ":-webkit-input" ":-moz" "-moz" "-ms-input";
-    @each $placeholder in $placeholders {
-        &:#{$placeholder}-placeholder {
-            @content;
-        }
+  $placeholders: ":-webkit-input" ":-moz" "-moz" "-ms-input";
+  @each $placeholder in $placeholders {
+    &:#{$placeholder}-placeholder {
+      @content;
     }
+  }
 }
 
 
 /**
  * Clearfix
  */
-
 @mixin clearfix {
-    &:before,
-    &:after{
-        content: " ";
-        display: table;
-    }
-    &:after{
-        clear: both;
-    }
+  &:before,
+  &:after {
+    content: " ";
+    display: table;
+  }
+
+  &:after {
+    clear: both;
+  }
 }