Added ad for clean code.

Author: Justin Martin

css/main.css

@@ -29,8 +29,12 @@ textarea {
 }
 
 img {
-  padding-top: 8px;
   border: none;
+  vertical-align: middle;
+}
+
+.gh-img {
+  padding-top: 2px;
 }
 
 h1 {
@@ -63,3 +67,12 @@ h1 {
   position: relative;
   top: 3px;
 }
+
+
+.book-ad {
+  display: inline-block;
+  padding-right: 8px;
+}
+.book-ad img {
+  height: 48px;
+}

img/clean_code.jpg

@@ -28,7 +28,8 @@ <h1>{} Json Diff</h1>
         		c-1.908-1.243-2.858-2.807-2.858-4.716l-4.853-130.47c0-2.667,0.953-4.665,2.856-5.996c2.474-2.093,4.758-3.14,6.854-3.14h62.809
         		c2.098,0,4.38,1.043,6.854,3.14c1.902,1.331,2.851,3.14,2.851,5.424L292.088,304.357z"/>
         </svg> Invalid JSON</span>
-        <a href="https://github.com/justspamjustin/online-json-diff" title="fork me on github!"><img src="img/gh.png"/></a>
+        <a class="book-ad" href="https://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882/ref=as_li_ss_il?ie=UTF8&qid=1470707326&sr=8-11&keywords=software+development&linkCode=li1&tag=justspamjusti-20&linkId=d0bf8301caceeff972273628705c7058" title="Clean Code: A Handbook of Agile Software Craftsmanship" target="_blank"><img src="img/clean_code.jpg"/></a>
+        <a href="https://github.com/justspamjustin/online-json-diff" title="fork me on github!" target="_blank"><img class="gh-img" src="img/gh.png"/></a>
       </div>
     </header>
     <div class="json-diff-input">