diff --git a/scss/mixins/_background.scss b/scss/mixins/_background.scss
index ea1543f..dcac6e1 100644
--- a/scss/mixins/_background.scss
+++ b/scss/mixins/_background.scss
@@ -60,7 +60,7 @@ $background-position-vertical-modes: array-concat((top, center, bottom), $css-de
       $h: nth-value($bp, 1);
       $h-valid: is-size($h) or is-percentage($h) or array-contains($background-position-horizontal-modes, $h);
 
-      $v: nth-value($bp, 2);
+      $v: if(length($bp) > 1, nth-value($bp, 2), center);
       $v-valid: is-size($v) or is-percentage($v) or array-contains($background-position-vertical-modes, $v);
 
       @return $h-valid and $v-valid;
@@ -465,30 +465,187 @@ $linear-gradient-directions: (to top, to top right, to right top, to right, to b
   @include linear-gradient-base(repeating-linear-gradient, $options...);
 }
 
-// $radial-gradient-shapes: (circle, ellipse);
+@function is-radial-gradient-size($gp) {
+  @return is-background-position($gp);
+}
+
+$radial-gradient-shapes: (circle, ellipse);
+
+@function is-radial-gradient-shape($gs) {
+  @return is-defined($gs) and array-contains($radial-gradient-shapes, $gs);
+}
+
+$radial-gradient-extent-keywords: (closest-side, closest-corner, farthest-side, farthest-corner, cover, contain);
+
+@function is-radial-gradient-extent-keyword($gek) {
+  @return is-defined($gek) and array-contains($radial-gradient-extent-keywords, $gek);
+}
+
+@function is-radial-gradient-position($gp) {
+  @return is-background-position($gp);
+}
+
+@function get-radial-gradient-definition($gd) {
+  $gradient-definition-split: string-split(inspect($gd), ' at ');
+  $gradient-definition: string-split(nth-value($gradient-definition-split, 1), ' ');
+  $gradient-position: center;
+
+  @if length($gradient-definition-split) > 1 {
+    $gradient-position: string-split(nth-value($gradient-definition-split, 2), ' ');
+  }
+
+  // $gradient-shape-width: null;
+  // $gradient-shape-height: null;
+  $gradient-shape: ellipse;
+  $gradient-extend-keyword: farthest-corner;
+
+  @each $gradient-definition-item in $gradient-definition {
+    $gradient-definition-item-index: index($gradient-definition, $gradient-definition-item);
+
+    // @if is-number-between($gradient-definition-item-index, 1, 2) {
+    //   $gradient-definition-item-number: to-number($gradient-definition-item);
+    //   @if is-relative-length($gradient-definition-item-number) or is-absolute-length($gradient-definition-item-number) {
+    //     @if $gradient-definition-item-index = 1 {
+    //       $gradient-shape-width: $gradient-definition-item-number;
+    //     }
+
+    //     @if $gradient-definition-item-index = 2 {
+    //       $gradient-shape-height: $gradient-definition-item-number;
+    //     }
+    //   }
+    // }
+
+    @if is-radial-gradient-shape($gradient-definition-item) {
+      $gradient-shape: $gradient-definition-item;
+    }
+    @else if is-radial-gradient-extent-keyword($gradient-definition-item) {
+      $gradient-extend-keyword: $gradient-definition-item;
+    }
+  }
+
+  // @if is-defined($gradient-shape-width) and is-null($gradient-shape-height) {
+  //   $gradient-shape-height: $gradient-shape-width;
+  // }
+
+  @if not is-radial-gradient-position($gradient-position) {
+    $gradient-position: center;
+  }
+
+  $radial-gradient-definition: (
+    shape: $gradient-shape,
+    extent-keyword: $gradient-extend-keyword,
+    position: $gradient-position
+  );
+
+  // @if is-defined($gradient-shape-width) and is-defined($gradient-shape-height) {
+  //   $radial-gradient-definition: extend($radial-gradient-definition, (
+  //     size: $gradient-shape-width $gradient-shape-height
+  //   ));
+  // }
+
+  @return $radial-gradient-definition;
+}
+
+@function is-radial-gradient-definition($gd) {
+  $gradient-definition-valid: false;
+
+  @if list-separator($gd) == space {
+    // $gradient-definition-size: get($gd, 'size');
+    $gradient-definition-shape: get($gd, 'shape');
+    $gradient-definition-extent-keyword: get($gd, 'extent-keyword');
+    $gradient-definition-position: get($gd, 'position');
+
+    $gradient-definition-valid: true;
+
+    // @if is-defined($gradient-definition-size) {
+    //   $gradient-definition-valid: is-radial-gradient-size($gradient-definition-size);
+    // }
+
+    // @if $gradient-definition-valid and is-defined($gradient-definition-shape) {
+    @if is-defined($gradient-definition-shape) {
+      $gradient-definition-valid: is-radial-gradient-shape($gradient-definition-shape);
+    }
+
+    @if $gradient-definition-valid and is-defined($gradient-definition-extent-keyword) {
+      $gradient-definition-valid: is-radial-gradient-extent-keyword($gradient-definition-extent-keyword);
+    }
+
+    @if $gradient-definition-valid and is-defined($gradient-definition-position) {
+      $gradient-definition-valid: is-radial-gradient-position($gradient-definition-position);
+    }
+  }
+
+  @return $gradient-definition-valid;
+}
+
+@function is-radial-gradient-options($options...) {
+  @if list-separator($options) == comma {
+    $definition: array-head($options);
+    $color-stops: $options;
 
-// @function is-radial-gradient-shape($gs) {
-//   @return is-defined($gs) and array-contains($radial-gradient-shapes, $gs);
-// }
+    @if not is-gradient-color-stop($definition) {
+      $color-stops: array-tail($options);
+    }
+    @else {
+      $definition: ellipse farthest-corner at center;
+    }
 
-// $radial-gradient-extent-modes: (closest-side, closest-corner, farthest-side, farthest-corner, cover, contain);
+    $definition: get-radial-gradient-definition($definition);
 
-// @function is-radial-gradient-extent($ge) {
-//   @return is-defined($ge) and array-contains($radial-gradient-extent-modes, $ge);
-// }
+    @return is-radial-gradient-definition($definition) and is-gradient-color-stops($color-stops...);
+  }
 
-// @function is-radial-gradient-position($gp) {
-//   @return is-background-position($gp);
-// }
+  @return false;
+}
 
-// @function is-radial-gradient-definition($gd) {
-//   @if is-array($gd) and list-separator($gd) == space {
-//     $gradient-definition: string-split($gd, ' at ');
+@mixin radial-gradient-base($function: radial-gradient, $options...) {
+  @if is-radial-gradient-options($options...) {
+    $definition: array-head($options);
+    $color-stops: $options;
 
-//     @warn($gradient-definition);
-//     @return true;
-//   }
+    @if not is-gradient-color-stop($definition) {
+      $color-stops: array-tail($options);
+    }
+    @else {
+      $definition: ellipse farthest-corner at center;
+    }
 
-//   @return false;
-// }
+    $definition: get-radial-gradient-definition($definition);
 
+    $radial-gradient-definition: '';
+
+    // $radial-gradient-definition-size: get($definition, 'size');
+
+    $radial-gradient-definition-shape: get($definition, 'shape');
+    $radial-gradient-definition-extent-keyword: get($definition, 'extent-keyword');
+    $radial-gradient-definition-position: get($definition, 'position');
+
+    // @if is-defined($radial-gradient-definition-size) {
+    //   $radial-gradient-definition: $radial-gradient-definition-size;
+    // }
+
+    @if is-defined($radial-gradient-definition-shape) {
+      $radial-gradient-definition: $radial-gradient-definition-shape;
+    }
+
+    @if is-defined($radial-gradient-definition-extent-keyword) {
+      $radial-gradient-definition: $radial-gradient-definition + ' ' + $radial-gradient-definition-extent-keyword;
+    }
+
+    @if is-defined($radial-gradient-definition-position) {
+      $radial-gradient-definition: $radial-gradient-definition + ' at ' + $radial-gradient-definition-position;
+    }
+
+    $radial-gradient-function-call: $function + '(' + $radial-gradient-definition + ',' + $color-stops + ')';
+
+    background-image: #{$radial-gradient-function-call};
+  }
+}
+
+@mixin radial-gradient($options...) {
+  @include radial-gradient-base(radial-gradient, $options...);
+}
+
+@mixin repeating-radial-gradient($options...) {
+  @include radial-gradient-base(repeating-radial-gradient, $options...);
+}
diff --git a/scss/types/_array.scss b/scss/types/_array.scss
index e450399..c71b85f 100644
--- a/scss/types/_array.scss
+++ b/scss/types/_array.scss
@@ -74,6 +74,18 @@
   @return $join-string;
 }
 
+@function array-remove($list, $value) {
+  $result: ();
+
+  @each $item in $list {
+    @if $item != $value {
+      $result: append($result, $item, list-separator($list));
+    }
+  }
+
+  @return $result;
+}
+
 @function array-remove-nth($list, $index) {
   $result: ();
 
diff --git a/scss/types/_number.scss b/scss/types/_number.scss
index dfcfe7e..c5df6b9 100644
--- a/scss/types/_number.scss
+++ b/scss/types/_number.scss
@@ -80,3 +80,61 @@
 @function is-percentage-number($pn) {
   @return is-number($pn) and is-number-between(unitstrip($pn), 0, 1);
 }
+
+///
+/// Casts a string into a number
+///
+/// @param {String | Number} $value - Value to be parsed
+///
+/// @return {Number}
+///
+@function to-number($value) {
+  @if type-of($value) == 'number' {
+    @return $value;
+  } @else if type-of($value) != 'string' {
+    $_: log('Value for `to-number` should be a number or a string.');
+  }
+
+  $result: 0;
+  $digits: 0;
+  $minus: str-slice($value, 1, 1) == '-';
+  $numbers: ('0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9);
+
+  @for $i from if($minus, 2, 1) through str-length($value) {
+    $character: str-slice($value, $i, $i);
+
+    @if not (index(map-keys($numbers), $character) or $character == '.') {
+      @return to-length(if($minus, -$result, $result), str-slice($value, $i));
+    }
+
+    @if $character == '.' {
+      $digits: 1;
+    } @else if $digits == 0 {
+      $result: $result * 10 + map-get($numbers, $character);
+    } @else {
+      $digits: $digits * 10;
+      $result: $result + map-get($numbers, $character) / $digits;
+    }
+  }
+
+  @return if($minus, -$result, $result);;
+}
+
+
+///
+/// Add `$unit` to `$value`
+///
+/// @param {Number} $value - Value to add unit to
+/// @param {String} $unit - String representation of the unit
+///
+/// @return {Number} - `$value` expressed in `$unit`
+///
+@function to-length($value, $unit) {
+  $units: ('px': 1px, 'cm': 1cm, 'mm': 1mm, '%': 1%, 'ch': 1ch, 'pc': 1pc, 'in': 1in, 'em': 1em, 'rem': 1rem, 'pt': 1pt, 'ex': 1ex, 'vw': 1vw, 'vh': 1vh, 'vmin': 1vmin, 'vmax': 1vmax);
+
+  @if not index(map-keys($units), $unit) {
+    $_: log('Invalid unit `#{$unit}`.');
+  }
+
+  @return $value * map-get($units, $unit);
+}
diff --git a/scss/types/_string.scss b/scss/types/_string.scss
index 150e9f1..600c73a 100644
--- a/scss/types/_string.scss
+++ b/scss/types/_string.scss
@@ -147,7 +147,7 @@
   @while $i!=null {
     $item: string-slice($s, 1, $i - 1);
     $split: array-concat($split, $item);
-    $s: string-slice($s, $i + 1);
+    $s: string-slice($s, $i + string-length($sep));
     $i: string-index($s, $sep);
   }