remove unused 300 & 600 font weights

Only 400 and "800" are used in the codebase for Open Sans.  And, we've only ever had up to 700 as available weights, so everything that is set to "800" is actually getting weight 700 (which looks better).

shared/naturalcrit/styles/fonts/fonts.css

@@ -1,12 +1,4 @@
 /* open-sans-latin-wght-normal */
-@font-face {
-	font-family   : 'Open Sans';
-	font-style    : normal;
-	font-weight   : 300;
-	src           : url('open-sans-latin-300-normal.woff2') format('woff2');
-	font-display  : swap;
-	unicode-range : U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD;
-}
 
 @font-face {
 	font-family   : 'Open Sans';
@@ -17,15 +9,11 @@
 	unicode-range : U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD;
 }
 
-@font-face {
-	font-family   : 'Open Sans';
-	font-style    : normal;
-	font-weight   : 600;
-	src           : url('open-sans-latin-600-normal.woff2') format('woff2');
-	font-display  : swap;
-	unicode-range : U+0000-00FF,U+0131,U+0152-0153,U+02BB-02BC,U+02C6,U+02DA,U+02DC,U+0304,U+0308,U+0329,U+2000-206F,U+20AC,U+2122,U+2191,U+2193,U+2212,U+2215,U+FEFF,U+FFFD;
-}
-
+/*
+* Nowhere is font-weight: 700 actually used with Open Sans, everything is set to 800.
+* But, 800 *is* too bold.  And since we don't have an 800 font file, it's just using the 
+* 700 font file and it looks fine.  Not sure it's worth changing everything to 700?
+*/
 @font-face {
 	font-family   : 'Open Sans';
 	font-style    : normal;