Add overflow-auto and overflow-hidden utilities

scss/utilities/_overflow.scss

@@ -0,0 +1,5 @@
+// stylelint-disable declaration-no-important
+
+@each $value in $overflows {
+  .overflow-#{$value} { overflow: $value !important; }
+}

scss/utilities/_position.scss

@@ -1,11 +1,6 @@
 // stylelint-disable declaration-no-important
 
 // Common values
-
-// Sass list not in variables since it's not intended for customization.
-// stylelint-disable-next-line scss/dollar-variable-default
-$positions: static, relative, absolute, fixed, sticky;
-
 @each $position in $positions {
   .position-#{$position} { position: $position !important; }
 }