update spacing on preview nav

Author: catarak

client/components/PreviewNav.jsx

@@ -7,7 +7,7 @@ const logoUrl = require('../images/p5js-logo-small.svg');
 const editorUrl = require('../images/code.svg');
 
 const PreviewNav = ({ owner, project }) => (
-  <nav className="nav">
+  <nav className="nav preview-nav">
     <div className="nav__items-left">
       <div className="nav__item-logo">
         <InlineSVG src={logoUrl} alt="p5.js logo" />

client/styles/components/_preview-nav.scss

@@ -12,3 +12,9 @@
     }
   }
 }
+
+.preview-nav {
+  .nav__item {
+    margin-left: #{5 / $base-font-size}rem;
+  }
+}