feat: rework style imports

src/styles/variables/_index.scss

@@ -3,4 +3,10 @@
 @import "variables";
 
 // the default values get overwritten by the definitions above
-@import "bulma/sass/utilities/_all";
+@import "bulma/sass/utilities/_all";
+
+// this is needed so that the shared form variables are globally defined aswell 
+@import "bulma/sass/form/shared";
+
+// since $tablet is defined by bulma we can just define it after importing the utilities
+$mobile: math.div($tablet, 2);

src/styles/variables/variables.scss

@@ -1,5 +1,3 @@
-@import 'colors';
-
 $white: #fff;
 $black: hsl(0, 0%, 4%) !default;
 $orange: #ff851b;