Refactored CSS classes.

A bit more BEM.

jquery.lightbox.css

@@ -11,27 +11,31 @@
 	-webkit-filter: none !important;
 	z-index: 9997;
 }
+
 .lightbox img {
 	display: block;
 	position: absolute;
 	border: 5px solid #fff;
 	box-shadow: 0 0 20px #000;
 	border-radius: 1px;
 }
+
 body.blurred > * {
   -webkit-filter: blur(2px);
   -webkit-transform: translate3d(0, 0, 0);
 }
-.lightbox-loading {
+
+.lightbox__loading {
 	background: url(loading.gif) center center no-repeat;
-	width: 31px;
-	height: 31px;
+	width: 32px;
+	height: 32px;
 	margin: -16px 0 0 -16px;
 	position: absolute;
-	top: 48%;
+	top: 50%;
 	left: 50%;
 }
-.lightbox-caption {
+
+.lightbox__caption {
 	display: none;
 	position: absolute;
 	left: 0;
@@ -43,7 +47,7 @@ body.blurred > * {
 	background: rgba(0,0,0,0.7);
 }
 
-.lightbox-caption p {
+.lightbox__caption p {
 	margin: 0 auto;
 	max-width: 70%;
 	display: inline-block;
@@ -55,7 +59,7 @@ body.blurred > * {
 	line-height: 18px;
 }
 
-.lightbox-button {
+.lightbox__button {
 	position: absolute;
 	z-index: 9999;
 	background: no-repeat center center;
@@ -68,27 +72,33 @@ body.blurred > * {
 	transition: 		all 0.3s;
 }
 
-.lightbox-button:hover,
-.lightbox-button:focus {
+.lightbox__button:hover,
+.lightbox__button:focus {
 	opacity: 1;
 	-webkit-transform: scale(1.4);
 	-moz-transform: scale(1.4);
 	-ms-transform: scale(1.4);
 	transform: scale(1.4);
 }
 
-.lightbox-close {
+.lightbox__close {
 	right: 10px;
 	top: 10px;
 	background-image: url('close.png');
 }
-.lightbox-next {
+
+.lightbox__nav {
+    top: 50%;
+    margin-top: -16px;
+}
+
+.lightbox__nav--next {
 	right: 10px;
-	top: 48%;
 	background-image: url('next.png');
 }
-.lightbox-previous {
+
+.lightbox__nav--prev {
 	left: 10px;
-	top: 48%;
 	background-image: url('previous.png');
 }
+}

jquery.lightbox.js

@@ -1,5 +1,5 @@
 /*!
- * jquery.lightbox.js v1.1
+ * jquery.lightbox.js v1.2
  * https://github.com/duncanmcdougall/Responsive-Lightbox
  * Copyright 2015 Duncan McDougall and other contributors; @license Creative Commons Attribution 2.5
  *
@@ -39,23 +39,21 @@
                 if (!plugin.lightbox) {
                     $('body').append(
                       '<div id="'+id+'" class="lightbox" style="display:none;">'+
-                      '<a href="#" class="lightbox-close lightbox-button"></a>' +
-                      '<div class="lightbox-nav">'+
-                      '<a href="#" class="lightbox-previous lightbox-button"></a>' +
-                      '<a href="#" class="lightbox-next lightbox-button"></a>' +
-                      '</div>' +
-                      '<div href="#" class="lightbox-caption"><p></p></div>' +
+                      '<a href="#" class="lightbox__close lightbox__button"></a>' +
+                      '<a href="#" class="lightbox__nav lightbox__nav--prev lightbox__button"></a>' +
+                      '<a href="#" class="lightbox__nav lightbox__nav--next lightbox__button"></a>' +
+                      '<div href="#" class="lightbox__caption"><p></p></div>' +
                       '</div>'
                     );
 
                     plugin.lightbox = $("#"+id);
-                    plugin.caption = $('.lightbox-caption', plugin.lightbox);
+                    plugin.caption = $('.lightbox__caption', plugin.lightbox);
                 }
 
                 if (plugin.items.length > 1 && opts.nav) {
-                    $('.lightbox-nav', plugin.lightbox).show();
+                    $('.lightbox__nav', plugin.lightbox).show();
                 } else {
-                    $('.lightbox-nav', plugin.lightbox).hide();
+                    $('.lightbox__nav', plugin.lightbox).hide();
                 }
 
                 plugin.bindEvents();
@@ -67,12 +65,12 @@
                     $("body").addClass("blurred");
                 }
                 $("img", plugin.lightbox).remove();
-                plugin.lightbox.fadeIn('fast').append('<span class="lightbox-loading"></span>');
+                plugin.lightbox.fadeIn('fast').append('<span class="lightbox__loading"></span>');
 
                 var img = $('<img src="' + $(plugin.current).attr('href') + '" draggable="false">');
 
                 $(img).load(function () {
-                    $('.lightbox-loading').remove();
+                    $('.lightbox__loading').remove();
                     plugin.lightbox.append(img);
                     plugin.image = $("img", plugin.lightbox).hide();
                     plugin.resizeImage();
@@ -179,19 +177,19 @@
                 });
 
                 // Previous click
-                $(plugin.lightbox).on('click', '.lightbox-previous', function () {
+                $(plugin.lightbox).on('click', '.lightbox__nav--prev', function () {
                     plugin.previous();
                     return false;
                 });
 
                 // Next click
-                $(plugin.lightbox).on('click', '.lightbox-next', function () {
+                $(plugin.lightbox).on('click', '.lightbox__nav--next', function () {
                     plugin.next();
                     return false;
                 });
 
                 // Close click
-                $(plugin.lightbox).on('click', '.lightbox-close', function () {
+                $(plugin.lightbox).on('click', '.lightbox__close', function () {
                     plugin.close();
                     return false;
                 });