fix image borders

build/js/build.js

@@ -158,7 +158,7 @@ Handlebars.registerHelper('image', function(options) {
 
   options.hash.examplePath = options.data.root.examplePath;
   options.hash.className = options.hash.className || '';
-  options.hash.caption = options.hash.caption || '';
+  options.hash.caption = options.hash.caption || undefined;
 
   if (options.hash.url.substring(0, 4) === 'http') {
     options.hash.examplePath = '';

threejs/lessons/resources/lesson.css

@@ -214,6 +214,7 @@ code {
 
 .threejs_image>img {
     width: 100%;
+    display: block;
 }
 .threejs_math {
   margin-left: auto;

threejs/lessons/threejs-setup.md

@@ -19,7 +19,7 @@ Next download one of these simple web servers
 If you'd prefer a web server with a user interface there's 
 [Servez](https://greggman.github.io/servez)
 
-{{{image url="resources/servez.gif" }}}
+{{{image url="resources/servez.gif" className="border" }}}
 
 Just point it at the folder where you unzipped the files, click "Start", then go to
 in your browser [`http://localhost:8080/`](http://localhost:8080/) or if you'd