Fix delete button

sass/elements/form.sass

@@ -272,6 +272,8 @@ $input-radius:              $radius !default
     display: flex
     justify-content: flex-start
     & > .control
+      flex-basis: 0
+      flex-shrink: 0
       &:not(:last-child)
         margin-bottom: 0
         margin-right: 0.75rem

sass/utilities/functions.sass

@@ -26,3 +26,11 @@
     @return rgba(#000, 0.7)
   @else
     @return #fff
+
+@function removeUnit($number)
+  @if type-of($number) == 'number' and not unitless($number)
+    @return $number / ($number * 0 + 1);
+  @return $number;
+
+@function roundToEvenNumber($number)
+  @return floor($number / 2) * 2

sass/utilities/mixins.sass

@@ -28,6 +28,11 @@
   top: 50%
 
 =delete
+  // We need even pixel dimensions to ensure the delete cross can be perfectly centered
+  $dimension-small: roundToEvenNumber(1.5 * removeUnit($size-6) * removeUnit($size-small)) * 1px
+  $dimension-normal: roundToEvenNumber(1.5 * removeUnit($size-6) * removeUnit($size-normal)) * 1px
+  $dimension-medium: roundToEvenNumber(1.5 * removeUnit($size-6) * removeUnit($size-medium)) * 1px
+  $dimension-large: roundToEvenNumber(1.5 * removeUnit($size-6) * removeUnit($size-large)) * 1px
   +unselectable
   -moz-appearance: none
   -webkit-appearance: none
@@ -37,13 +42,13 @@
   cursor: pointer
   display: inline-block
   font-size: $size-normal
-  height: 1.5em
+  height: $dimension-normal
   outline: none
   position: relative
   transform: rotate(45deg)
   transform-origin: center center
   vertical-align: top
-  width: 1.5em
+  width: $dimension-normal
   &:before,
   &:after
     background-color: $white
@@ -66,11 +71,14 @@
     background-color: rgba($black, 0.4)
   // Sizes
   &.is-small
-    font-size: $size-small
+    height: $dimension-small
+    width: $dimension-small
   &.is-medium
-    font-size: $size-medium
+    height: $dimension-medium
+    width: $dimension-medium
   &.is-large
-    font-size: $size-large
+    height: $dimension-large
+    width: $dimension-large
 
 =fa($size, $dimensions)
   display: inline-block