Specify image dimensions in the HTML.

site/_includes/css/style.css

@@ -157,8 +157,6 @@ body > footer img {
   position: relative;
   top: 8px;
   margin-left: 5px;
-  width: 100px;
-  height: 30px;
   opacity: .8;
   padding: 1px;
   -webkit-transition: opacity .2s;
@@ -591,8 +589,6 @@ article h2:first-child {
 }
 
 .avatar {
-  width: 24px;
-  height: 24px;
   border-radius: 3px;
   display: inline-block;
   vertical-align: middle;

site/_includes/footer.html

@@ -7,7 +7,7 @@
       <p>
         Proudly hosted by
         <a href="https://github.com">
-          <img src="/img/footer-logo.png" alt="GitHub • Social coding">
+          <img src="/img/footer-logo.png" width="100" height="30" alt="GitHub • Social coding">
         </a>
       </p>
     </div>

site/_includes/news_item.html

@@ -14,7 +14,7 @@
       {{ post.date | date_to_string }}
     </span>
     <a href="https://github.com/{{ post.author }}" class="post-author">
-      <img src="https://github.com/{{ post.author }}.png" class="avatar" alt="{{ post.author }}">
+      <img src="https://github.com/{{ post.author }}.png" class="avatar" alt="{{ post.author }}" width="24" height="24">
       {{ post.author }}
     </a>
   </div>

site/_layouts/news_item.html

@@ -17,7 +17,7 @@ layout: news
       {{ page.date | date_to_string }}
     </span>
     <a href="https://github.com/{{ page.author }}" class="post-author">
-      <img src="https://github.com/{{ page.author }}.png" class="avatar" alt="{{ page.author }}">
+      <img src="https://github.com/{{ page.author }}.png" class="avatar" alt="{{ page.author }}" width="24" height="24">
       {{ page.author }}
     </a>
   </div>

site/index.html

@@ -76,7 +76,7 @@ overview: true
     <div class="unit whole">
       <div class="grid pane">
         <div class="unit whole center-on-mobiles">
-          <img src="img/octojekyll.png" alt="Free Jekyll hosting on GitHub Pages">
+          <img src="img/octojekyll.png" width="300" height="251" alt="Free Jekyll hosting on GitHub Pages">
           <div class="pane-content">
             <h2 class="center-on-mobiles"><strong>Free hosting</strong> with GitHub Pages</h2>
             <p>Sick of dealing with hosting companies? <a href="http://pages.github.com/">GitHub Pages</a> are <em>powered by Jekyll</em>, so you can easily deploy your site using GitHub for free&mdash;<a href="https://help.github.com/articles/setting-up-a-custom-domain-with-pages">custom domain name</a> and&nbsp;all.</p>