Refactored Sass

Merged SCSS from various recent projects and implemented some of the latest features from InuitCSS.

When using the SCSS structure in your own project, modify the ‘settings/config*.scss’ files and leave ‘settings/core.scss’ intact.

Changes:
- Updated Normalize to 5.0.0;
- Migrated imports to ‘main.scss’;
- Split ‘settings.scss’ into smaller parts;
- Revised variable names for settings;
- Added spacing unit variables;
- Replaced ‘objects/grid.scss’ with ‘objects/layout.scss’ (from inuitcss);
- Added ‘objects/crop.scss’ and ‘objects/ratio.scss’ (from inuitcss);
- Added @font-face mixin/function from Bourbon;
- Added various new functions and mixins (widths, font-size, truncation,…);
- Renamed Trumps to Utilities;
- Added vatious new Utilities (print, states, spacing, widths);
- Reorganized Utilities into topics;

assets/styles/tools/_functions.scss

@@ -1,14 +1,146 @@
-// ==========================================================================
-// Functions
-// ==========================================================================
-@function em($px, $base: $font-size) {
-    @return ($px / $base) * 1em;
+///
+/// Tools / Functions
+/// ============================================================================
+///
+
+///
+/// Removes units (px, em, etc.) from a given number.
+///
+/// @param  {Number} $value - The numeric value to strip units from.
+/// @return {Number} A unitless numeric value.
+///
+@function strip-unit($value)
+{
+    @return $value / ($value * 0 + 1);
 }
 
-@function rem($px, $base: $font-size) {
-    @return ($px / $base) * 1rem;
+///
+/// Converts the given pixel value to its EM quivalent.
+///
+/// @param  {Number} $size                     - The pixel value to convert.
+/// @param  {Number} $base [$global-font-size] - The assumed base font size.
+/// @return {Number} Scalable pixel value in EMs.
+///
+@function em($size, $base: $global-font-size)
+{
+    @if (type-of($size) == number) {
+        @if (unit($size) != "px") {
+            @error "`#{$size}` needs to be a pixel value.";
+        }
+    } @else {
+        @error "`#{$size}` needs to be a number.";
+    }
+
+    @if (type-of($base) == number) {
+        @if (unit($base) != "px") {
+            @error "`#{$base}` needs to be a pixel value.";
+        }
+    } @else {
+        @error "`#{$base}` needs to be a number.";
+    }
+
+    @return ($size / $base) * 1em;
 }
 
-@function span($fraction) {
-    @return $fraction * 100%;
+///
+/// Converts the given pixel value to its REM quivalent.
+///
+/// @param  {Number} $size                     - The pixel value to convert.
+/// @param  {Number} $base [$global-font-size] - The assumed base font size.
+/// @return {Number} Scalable pixel value in REMs.
+///
+@function rem($size, $base: $global-font-size)
+{
+    @if (type-of($size) == number) {
+        @if (unit($size) != "px") {
+            @error "`#{$size}` needs to be a pixel value.";
+        }
+    } @else {
+        @error "`#{$size}` needs to be a number.";
+    }
+
+    @if (type-of($base) == number) {
+        @if (unit($base) != "px") {
+            @error "`#{$base}` needs to be a pixel value.";
+        }
+    } @else {
+        @error "`#{$base}` needs to be a number.";
+    }
+
+    @return ($size / $base) * 1rem;
 }
+
+///
+/// Converts a number to a percentage.
+///
+/// @alias  percentage()
+/// @link   http://sassdoc.com/annotations/#alias
+/// @param  {Number} $number - The value to convert.
+/// @return {Number} A percentage.
+///
+@function span($number) {
+    @return percentage($number);
+}
+
+///
+/// Checks if a list contains a value(s).
+///
+/// @link   https://github.com/thoughtbot/bourbon/blob/master/core/bourbon/validators/_contains.scss
+/// @param  {List} $list   - The list to check against.
+/// @param  {List} $values - A single value or list of values to check for.
+/// @return {Boolean}
+/// @access private
+///
+@function list-contains(
+    $list,
+    $values...
+) {
+    @each $value in $values {
+        @if type-of(index($list, $value)) != "number" {
+            @return false;
+        }
+    }
+
+    @return true;
+}
+
+///
+/// Resolve whether a rule is important or not.
+///
+/// @param  {Boolean}     $flag - Whether a rule is important (TRUE) or not (FALSE).
+/// @return {String|Null} Returns `!important` or NULL.
+///
+@function important($flag: false)
+{
+    @if ($flag == true) {
+        @return !important;
+    } @elseif ($important == false) {
+        @return null;
+    } @else {
+        @error "`#{$flag}` needs to be `true` or `false`."
+    }
+}
+
+///
+/// Determine if the current context is for a WYSIWYG editor.
+///
+/// @requires {String} $context - The global context of the stylesheet.
+/// @return   {Boolean} If the $context is set to "editor".
+///
+@function is-editor()
+{
+    @return ('editor' == $context);
+}
+
+///
+/// Determine if the current context is for the front-end.
+///
+/// @requires {String} $context - The global context of the stylesheet.
+/// @return   {Boolean} If the $context is set to "frontend".
+///
+@function is-frontend()
+{
+    @return ('frontend' == $context);
+}
+
+$context: 'frontend' !default;