diff --git a/test_book/book.toml b/test_book/book.toml
index a30500763c..4f07778c70 100644
--- a/test_book/book.toml
+++ b/test_book/book.toml
@@ -9,6 +9,8 @@ edition = "2018"
 
 [output.html]
 mathjax-support = true
+additional-css = ["orange.css"]
+additional-theme = ["Orange"]
 
 [output.html.playground]
 editable = true
diff --git a/test_book/orange.css b/test_book/orange.css
new file mode 100644
index 0000000000..a4e325887d
--- /dev/null
+++ b/test_book/orange.css
@@ -0,0 +1,39 @@
+.orange {
+    --bg: #f6f6ef;
+    --fg: Black;
+
+    --sidebar-bg: #ff6600;
+    --sidebar-fg: Black;
+    --sidebar-non-existant: color-mix(in srgb, var(--sidebar-bg) 75%, Black);
+    --sidebar-active: White;
+    --sidebar-spacer: color-mix(in srgb, var(--sidebar-bg) 95%, Black);
+
+    --scrollbar: #8F8F8F;
+
+    --icons: #747474;
+    --icons-hover: #000000;
+
+    --links: #828282;
+
+    --inline-code-color: Black
+
+    --theme-popup-bg: #fafafa;
+    --theme-popup-border: #cccccc;
+    --theme-hover: #e6e6e6;
+
+    --quote-bg: #e9e9ed;
+    --quote-border: #8f8f9d;
+
+    --table-border-color: hsl(0, 0%, 95%);
+    --table-header-bg: hsl(0, 0%, 80%);
+    --table-alternate-bg: hsl(0, 0%, 97%);
+
+    --searchbar-border-color: #aaa;
+    --searchbar-bg: #fafafa;
+    --searchbar-fg: #000;
+    --searchbar-shadow-color: #aaa;
+    --searchresults-header-fg: #666;
+    --searchresults-border-color: #888;
+    --searchresults-li-bg: #e4f2fe;
+    --search-mark-bg: #a2cff5;
+}