fix: add global value definitions

Author: Kyle Sosnowski

css/basscss.css

@@ -694,3 +694,10 @@
 
 .display-none{ display:none !important }
 
+@value space-1: 0.5rem;
+
+@value space-2: 1rem;
+
+@value space-3: 2rem;
+
+@value space-4: 3rem;

src/basscss.css

@@ -12,3 +12,7 @@
 @import 'basscss-border';
 @import 'basscss-hide';
 
+@value space-1: 0.5rem;
+@value space-2: 1rem;
+@value space-3: 2rem;
+@value space-4: 3rem;