Add font-display for font fallback, move body font style to _fonts.scss

assets/_fonts.scss

@@ -3,6 +3,7 @@
   font-family: 'Oxygen';
   font-style: normal;
   font-weight: 300;
+  font-display: swap;
   src: url('/fonts/oxygen-v8-latin-300.eot'); /* IE9 Compat Modes */
   src: local('Oxygen Light'), local('Oxygen-Light'),
        url('/fonts/oxygen-v8-latin-300.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
@@ -16,6 +17,7 @@
   font-family: 'Oxygen';
   font-style: normal;
   font-weight: 400;
+  font-display: swap;
   src: url('/fonts/oxygen-v8-latin-regular.eot'); /* IE9 Compat Modes */
   src: local('Oxygen Regular'), local('Oxygen-Regular'),
        url('/fonts/oxygen-v8-latin-regular.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
@@ -29,6 +31,7 @@
   font-family: 'Oxygen';
   font-style: normal;
   font-weight: 700;
+  font-display: swap;
   src: url('/fonts/oxygen-v8-latin-700.eot'); /* IE9 Compat Modes */
   src: local('Oxygen Bold'), local('Oxygen-Bold'),
        url('/fonts/oxygen-v8-latin-700.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
@@ -42,6 +45,7 @@
   font-family: 'Oxygen Mono';
   font-style: normal;
   font-weight: 400;
+  font-display: swap;
   src: url('/fonts/oxygen-mono-v6-latin-regular.eot'); /* IE9 Compat Modes */
   src: local('Oxygen Mono'), local('OxygenMono-Regular'),
        url('/fonts/oxygen-mono-v6-latin-regular.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */
@@ -50,3 +54,7 @@
        url('/fonts/oxygen-mono-v6-latin-regular.ttf') format('truetype'), /* Safari, Android, iOS */
        url('/fonts/oxygen-mono-v6-latin-regular.svg#OxygenMono') format('svg'); /* Legacy iOS */
 }
+
+body {
+  font-family: "Oxygen", sans-serif;
+}

assets/book.scss

@@ -2,7 +2,6 @@
 @import "variables";
 @import "markdown";
 @import "utils";
-@import "fonts";
 
 html {
   font-size: $font-size-base;
@@ -19,8 +18,8 @@ body {
 body {
   color: $body-font-color;
   background: $body-background;
-	
-  font-family: "Oxygen",sans-serif;
+
+  font-family: sans-serif;
   font-weight: $body-font-weight;
 
   text-rendering: optimizeLegibility;
@@ -68,7 +67,7 @@ aside nav ul {
   }
 
   a:hover {
-    opacity: .5;
+    opacity: 0.5;
   }
 
   ul {
@@ -111,8 +110,9 @@ ul.pagination {
 .book-section-flat {
   margin-bottom: $padding-16 * 2;
 
-  > a, > span {
-    font-weight: 600
+  > a,
+  > span {
+    font-weight: 600;
   }
 
   > ul {
@@ -238,5 +238,8 @@ aside nav,
   }
 }
 
+// Add fonts
+@import "fonts";
+
 // Add custom defined styles
-@import 'custom'
+@import "custom";