#4279, preserve em units for math, fix h1-h5 to use exact decimals as well

src/themes/default/globals/site.variables

@@ -58,13 +58,13 @@
 ---------------*/
 
 @headerFontWeight : bold;
-@headerLineHeight : 1.2857em;
+@headerLineHeight : unit((18 / 14), em);
 
-@h1 : 2rem;
-@h2 : 1.714rem;
-@h3 : 1.28rem;
-@h4 : 1.071rem;
-@h5 : 1rem;
+@h1 : unit((28 / 14), rem);
+@h2 : unit((24 / 14), rem);
+@h3 : unit((18 / 14), rem);
+@h4 : unit((15 / 14), rem);
+@h5 : unit((14 / 14), rem);
 
 /*--------------
    Form Input
@@ -82,7 +82,7 @@
 @inputPlaceholderFocusColor: lighten(@inputColor, 45);
 
 /* Line Height Default For Inputs in Browser (Descendors are 17px at 14px base em) */
-@inputLineHeight: (17 / 14);
+@inputLineHeight: unit((17 / 14), em);
 
 /*-------------------
     Focused Input