Add donate button

README.md

@@ -2,3 +2,5 @@
 
 <!-- {.massive-header.-with-tagline} -->
 > An optimization handbook from a high level point of view.
+
+<a class="badge" target="_blank" href="https://paypal.me/kikobeats"><img src="https://img.shields.io/badge/donate-paypal-blue.svg?style=flat-square" alt="Donate"></a>

assets/scss/_markdown.scss

@@ -127,7 +127,7 @@ html .markdown-body {
   max-width: 740px;
 }
 
-html .markdown-body a {
+html .markdown-body a:not(.badge) {
   font-weight: bold;
   color: $secondary-color;
   border-bottom: 1px solid $secondary-color;
@@ -224,7 +224,7 @@ html .markdown-body h4 {
     padding-top: 0;
     margin-top: 0;
     margin-bottom: 0;
-    padding-bottom: 21vh;
+    padding-bottom: 10vh;
     font-size: 4em;
     color: $gray-light;
     padding-right: 10%;

bibliography.md

@@ -13,5 +13,6 @@
 
 * [Optimization killers](https://github.com/petkaantonov/bluebird/wiki/Optimization-killers).
 * [Performance Tips for JavaScript in V8](http://www.html5rocks.com/en/tutorials/speed/v8/).
+* [Let’s Write Fast JavaScript](https://medium.com/@mdibaiee/lets-write-fast-javascript-2b03c5575d9e).
 * [Writing Fast, Memory-Efficient JavaScript](http://www.smashingmagazine.com/2012/11/writing-fast-memory-efficient-javascript/#de-referencing-misconceptions).
 * [Unquoted property names / object keys in JavaScript](https://mathiasbynens.be/notes/javascript-properties).