Enfored sentence case with mixin

Author: cwhite911

theme.scss

@@ -301,6 +301,13 @@ $important: false) {
   filter: hue-rotate(#{$hue}deg) saturate($saturation-factor) brightness(#{$brightness-factor})#{$important-flag}; 
 }
 
+@mixin sentence-case() {
+  text-transform: lowercase;
+  &::first-letter {
+    text-transform: uppercase;
+  }
+}
+
 /*-- scss:rules --*/
 
 /* Header Styles
@@ -312,15 +319,16 @@ h1 {
   font-size: 2.25em;
   line-height: 1.3;
   margin: 0 0 1em;
+  @include sentence-case;
 }
 
 h2 {
   font-family: $gs-grass-font--light;
   color: $gs-secondary-light-color;
   font-size: 2em;
-  text-transform: none;
   line-height: 1.4;
   margin: .64em 0 .64em;
+  @include sentence-case;
 }
 
 h3 {
@@ -330,6 +338,11 @@ h3 {
   letter-spacing: -.01em;
   line-height: 1.5;
   margin: 1.6em 0 .8em;
+  @include sentence-case;
+}
+
+h4, h5, h6 {
+  @include sentence-case;
 }
 
 /* Code Styles