Change the animation in the main nav (#521)

Closes #520

Author: Ryan Wilson

static/header.less

@@ -149,7 +149,7 @@
                 &:before {
                     content: '';
                     position: absolute;
-                    bottom: 20px;
+                    bottom: 8px;
                     left: 0px;
                     width: 100%;
                     height: 4px;
@@ -159,7 +159,6 @@
                     transition: all 0.4s ease-in-out;
                 }
                 &:hover:before {
-                    bottom: 8px;
                     opacity: 1;
                 }
             }
@@ -168,7 +167,6 @@
                     color: @link-color;
                 }
                 > a:before {
-                    bottom: 8px;
                     opacity: 1;
                     background-color: @link-color;
                     cursor: default;