Use Oxygen font

assets/_variables.scss

@@ -26,7 +26,7 @@ $color-visited-link: #8440f1;
 
 $body-background: white;
 $body-font-color: $gray-800;
-$body-font-weight: 300;
+$body-font-weight: 400;
 $body-min-width: 25rem;
 
 $nav-background: $body-background; //$gray-100;

assets/book.scss

@@ -15,7 +15,7 @@ html, body {
 body {
   color: $body-font-color;
   background: $body-background;
-  font-family: 'Roboto', sans-serif;
+  font-family: 'Oxygen', sans-serif;
   font-weight: $body-font-weight;
 
   box-sizing: border-box;
@@ -100,7 +100,6 @@ main {
 
     .brand {
       margin-top: 0;
-      margin-bottom: $padding-16;
     }
 
     nav {