Update documentation comments in src modules.

src/_background-size.css

@@ -2,6 +2,18 @@
 
    BACKGROUND SIZE
 
+   Base:
+    bg = background-size
+
+   Modifiers:
+    cv = cover
+    cn = contain
+
+   Media Query Extensions:
+     -ns = not-small
+     -m  = medium
+     -l  = large
+
 */
 
   .bg-cv  {               background-size: cover; }

src/_base.css

@@ -1,3 +1,9 @@
+/*
+
+  BASE
+
+*/
+
 html,
 body {
   height: 100%;

src/_border-colors.css

@@ -2,6 +2,16 @@
 
    BORDER COLORS
 
+   Use in cobmination with the _borders.css module
+   Or for more flexibility the _border-styles.css and _border-widths.css modules
+
+   Base:
+     b-- = border
+
+   Modifiers:
+     Add a border color. There is a one to one mapping of color values
+     in the _colors.css module.
+
  */
 
 .b--black {        border-color: var(--black); }

src/_border-widths.css

@@ -1,4 +1,5 @@
 /*
+
    BORDER WIDTHS
 
    Base:

src/_widths.css

@@ -2,6 +2,34 @@
 
    WIDTHS
 
+   Base:
+     w = width
+
+   Modifiers
+     1 = 1st step in width scale
+     2 = 2nd step in width scale
+     3 = 3rd step in width scale
+     4 = 4th step in width scale
+     5 = 5th step in width scale
+
+     -10  = literal value 10%
+     -20  = literal value 20%
+     -25  = literal value 25%
+     -33  = literal value 33%
+     -34  = literal value 34%
+     -40  = literal value 40%
+     -50  = literal value 50%
+     -60  = literal value 60%
+     -75  = literal value 75%
+     -80  = literal value 80%
+     -100 = literal value 100%
+
+
+   Media Query Extensions:
+     -ns = not-small
+     -m  = medium
+     -l  = large
+
 */
 
 /* Width Scale */