diff --git a/modules/book/book.admin.css b/modules/book/book.admin.css
index e69de29..655d219 100644
--- a/modules/book/book.admin.css
+++ b/modules/book/book.admin.css
@@ -0,0 +1,12 @@
+#book-outline {
+  min-width: 40em;
+}
+html.js #edit-book-pick-book {
+  display: none;
+}
+.form-item-book-bid .description {
+  clear: both;
+}
+#book-admin-edit .form-item {
+  float: left;
+}
diff --git a/modules/book/book.admin.inc b/modules/book/book.admin.inc
index 7b9dea3..73b5835 100644
--- a/modules/book/book.admin.inc
+++ b/modules/book/book.admin.inc
@@ -174,6 +174,7 @@ function _book_admin_table($node, &$form) {
  * @see book_admin_edit()
  */
 function _book_admin_table_tree($tree, &$form) {
+  drupal_add_css(drupal_get_path('module', 'book') . '/book.admin.css');
   // The delta must be big enough to give each node a distinct value.
   $count = count($tree);
   $delta = ($count < 30) ? 15 : intval($count / 2) + 1;
diff --git a/modules/book/book.css b/modules/book/book.css
deleted file mode 100644
index a8d2136..0000000
--- a/modules/book/book.css
+++ /dev/null
@@ -1,54 +0,0 @@
-
-.book-navigation .menu {
-  border-top: 1px solid #888;
-  padding: 1em 0 0 3em; /* LTR */
-}
-.book-navigation .page-links {
-  border-top: 1px solid #888;
-  border-bottom: 1px solid #888;
-  text-align: center;
-  padding: 0.5em;
-}
-.book-navigation .page-previous {
-  text-align: left;
-  width: 42%;
-  display: block;
-  float: left; /* LTR */
-}
-.book-navigation .page-up {
-  margin: 0 5%;
-  width: 4%;
-  display: block;
-  float: left; /* LTR */
-}
-.book-navigation .page-next {
-  text-align: right;
-  width: 42%;
-  display: block;
-  float: right;
-}
-#book-outline {
-  min-width: 56em;
-}
-.book-outline-form .form-item {
-  margin-top: 0;
-  margin-bottom: 0;
-}
-html.js #edit-book-pick-book {
-  display: none;
-}
-.form-item-book-bid .description {
-  clear: both;
-}
-#book-admin-edit select {
-  margin-right: 24px;
-}
-#book-admin-edit select.progress-disabled {
-  margin-right: 0;
-}
-#book-admin-edit tr.ajax-new-content {
-  background-color: #ffd;
-}
-#book-admin-edit .form-item {
-  float: left;
-}
diff --git a/modules/book/book.info b/modules/book/book.info
index 0f4d2b1..15984ad 100644
--- a/modules/book/book.info
+++ b/modules/book/book.info
@@ -5,4 +5,4 @@ version = VERSION
 core = 8.x
 files[] = book.test
 configure = admin/content/book/settings
-stylesheets[all][] = book.css
+stylesheets[all][] = book.theme.css
diff --git a/modules/book/book.theme.css b/modules/book/book.theme.css
index e69de29..d53656e 100644
--- a/modules/book/book.theme.css
+++ b/modules/book/book.theme.css
@@ -0,0 +1,28 @@
+.book-navigation .menu {
+  border-top: 1px solid #888;
+  padding: 1em 0 0 3em; /* LTR */
+}
+.book-navigation .page-links {
+  border-top: 1px solid #888;
+  border-bottom: 1px solid #888;
+  text-align: center;
+  padding: 0.5em;
+}
+.book-navigation .page-previous {
+  text-align: left;
+  width: 42%;
+  display: block;
+  float: left; /* LTR */
+}
+.book-navigation .page-up {
+  margin: 0 5%;
+  width: 4%;
+  display: block;
+  float: left; /* LTR */
+}
+.book-navigation .page-next {
+  text-align: right;
+  width: 42%;
+  display: block;
+  float: right;
+}