diff --git a/book.toml b/book.toml
index 614bac6..a9fa90f 100644
--- a/book.toml
+++ b/book.toml
@@ -15,3 +15,4 @@ command = "python3 tools/mdbook_zh_preprocessor.py"
 git-repository-url = "https://github.com/openmlsys/openmlsys-zh"
 mathjax-support = true
 preferred-dark-theme = "navy"
+additional-css = ["theme/dark-mode-images.css"]
diff --git a/theme/dark-mode-images.css b/theme/dark-mode-images.css
new file mode 100644
index 0000000..43917b8
--- /dev/null
+++ b/theme/dark-mode-images.css
@@ -0,0 +1,8 @@
+/* 暗色模式下为图片添加浅灰色背景，提高透明背景图片的可读性 */
+.navy img,
+.coal img,
+.ayu img {
+    background-color: #e8e8e8;
+    border-radius: 4px;
+    padding: 8px;
+}