diff --git a/.env.example b/.env.example
index 2013aa5..cf935ec 100644
--- a/.env.example
+++ b/.env.example
@@ -17,5 +17,6 @@ BOOK_LABEL_WEBSITE=Your website (optional):
 BOOK_LABEL_MESSAGE=Your message:
 BOOK_TEXTAREA_ROWS=8
 BOOK_TEXTAREA_COLS=60
+# BOOK_STYLE_FILE=./my-styles.css
 # BOOK_STYLE=.entry-name { font-weight: bold; }
 # BOOK_TEMPLATE=./templates/default.html
diff --git a/module.nix b/module.nix
index 6464d15..1bbe6ef 100644
--- a/module.nix
+++ b/module.nix
@@ -87,6 +87,12 @@ in
       description = "Custom CSS injected into a style tag. Use class names: .guestbook-form, .guestbook-prompt, .guestbook-label, .guestbook-input, .guestbook-textarea, .guestbook-button, .entry-header, .entry-name, .entry-website, .entry-body, .entry-separator";
     };
 
+    styleFile = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = "Path to a CSS file. Takes precedence over style.";
+    };
+
     formPrompt = mkOption {
       type = types.str;
       default = "If you visited my site, please sign my guestbook!";
@@ -177,6 +183,8 @@ in
           BOOK_OPEN_REGISTRATION = if cfg.openRegistration then "true" else "false";
           BOOK_SEPARATOR = cfg.separator;
           BOOK_STYLE = cfg.style;
+        } // lib.optionalAttrs (cfg.styleFile != null) {
+          BOOK_STYLE_FILE = cfg.styleFile;
           BOOK_FORM_PROMPT = cfg.formPrompt;
           BOOK_BUTTON_TEXT = cfg.buttonText;
           BOOK_LABEL_NAME = cfg.labelName;
diff --git a/src/config.rs b/src/config.rs
index b552b1e..75e93bd 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -72,7 +72,14 @@ impl Config {
                 std::fs::read_to_string(&path)
                     .unwrap_or_else(|e| panic!("failed to read template {path}: {e}"))
             }),
-            style: env::var("BOOK_STYLE").unwrap_or_default(),
+            style: env::var("BOOK_STYLE_FILE")
+                .ok()
+                .map(|path| {
+                    std::fs::read_to_string(&path)
+                        .unwrap_or_else(|e| panic!("failed to read style file {path}: {e}"))
+                })
+                .or_else(|| env::var("BOOK_STYLE").ok())
+                .unwrap_or_default(),
             form_prompt: env::var("BOOK_FORM_PROMPT")
                 .unwrap_or_else(|_| "If you visited my site, please sign my guestbook!".into()),
             button_text: env::var("BOOK_BUTTON_TEXT")