diff --git a/.env.example b/.env.example
index 11a34fc..2661515 100644
--- a/.env.example
+++ b/.env.example
@@ -12,3 +12,9 @@ DB_TYPE=sqlite
 
 # Database write interval in seconds (0 for real-time)
 DB_INTERVAL=60
+
+# Log level: either 'debug' | 'info' | 'warn' | 'error' | 'none'
+LOG_LEVEL=debug
+
+# Google Analytics `G-Tag` ID
+# GA_ID=G-XXXX
diff --git a/.gitignore b/.gitignore
index b329f95..b079941 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,7 @@ count.db
 
 # misc
 .DS_Store
+.env
 .env.local
 .env.development.local
 .env.test.local
diff --git a/assets/script.js b/assets/script.js
index 9babf1a..27b8aed 100644
--- a/assets/script.js
+++ b/assets/script.js
@@ -145,8 +145,8 @@
 
   const lazyLoadOptions = {
     selector: 'img[data-src]:not([src])',
-    loading: '/img/loading.svg',
-    failed: '/img/failed.svg',
+    loading: `${__global_data.site}/img/loading.svg`,
+    failed: `${__global_data.site}/img/failed.svg`,
     rootMargin: '200px',
     threshold: 0.01
   };
diff --git a/index.js b/index.js
index ac994ba..66e0a3c 100644
--- a/index.js
+++ b/index.js
@@ -8,7 +8,7 @@ const { z } = require("zod");
 const db = require("./db");
 const { themeList, getCountImage } = require("./utils/themify");
 const { cors, ZodValid } = require("./utils/middleware");
-const { randomArray } = require("./utils");
+const { randomArray, logger } = require("./utils");
 
 const app = express();
 
@@ -19,8 +19,10 @@ app.set("view engine", "pug");
 
 app.get('/', (req, res) => {
   const site = process.env.APP_SITE || `${req.protocol}://${req.get('host')}`
+  const ga_id = process.env.GA_ID || null
   res.render('index', {
     site,
+    ga_id,
     themeList,
   })
 });
@@ -71,7 +73,7 @@ app.get(["/@:name", "/get/@:name"],
 
     res.send(renderSvg);
 
-    console.log(
+    logger.debug(
       data,
       { theme, ...req.query },
       `ip: ${req.headers['x-forwarded-for'] || req.connection.remoteAddress}`,
@@ -93,11 +95,11 @@ app.get("/record/@:name", async (req, res) => {
 app.get("/heart-beat", (req, res) => {
   res.set("cache-control", "max-age=0, no-cache, no-store, must-revalidate");
   res.send("alive");
-  console.log("heart-beat");
+  logger.debug("heart-beat");
 });
 
 const listener = app.listen(process.env.APP_PORT || 3000, () => {
-  console.log("Your app is listening on port " + listener.address().port);
+  logger.info("Your app is listening on port " + listener.address().port);
 });
 
 let __cache_counter = {};
@@ -116,7 +118,7 @@ async function pushDB() {
 
   try {
     needPush = false;
-    console.log("pushDB", __cache_counter);
+    logger.info("pushDB", __cache_counter);
 
     const counters = Object.keys(__cache_counter).map((key) => {
       return {
@@ -128,7 +130,7 @@ async function pushDB() {
     await db.setNumMulti(counters);
     __cache_counter = {};
   } catch (error) {
-    console.log("pushDB is error: ", error);
+    logger.error("pushDB is error: ", error);
   }
 }
 
@@ -151,7 +153,7 @@ async function getCountByName(name, num) {
 
     return { name, num: __cache_counter[name] };
   } catch (error) {
-    console.log("get count by name is error: ", error);
+    logger.error("get count by name is error: ", error);
     return defaultCount;
   }
 }
diff --git a/utils/index.js b/utils/index.js
index 687737b..f369e06 100644
--- a/utils/index.js
+++ b/utils/index.js
@@ -1,8 +1,28 @@
+const log_level = process.env.LOG_LEVEL || 'info';
+
+const levels = ['none', 'error', 'warn', 'info', 'debug'];
+const currentLevelIndex = levels.indexOf(log_level);
+
+const buildLogMethod = (level) => (...args) => {
+  const levelIndex = levels.indexOf(level);
+  const shouldLog = levelIndex <= currentLevelIndex;
+
+  if (shouldLog) {
+    console[level](...args);
+  }
+};
+
 module.exports = {
   randomArray: (arr) => {
     return arr[Math.floor(Math.random() * arr.length)]
   },
   toFixed: (num, digits = 2) => {
     return parseFloat(Number(num).toFixed(digits))
+  },
+  logger: {
+    debug: buildLogMethod('debug'),
+    info: buildLogMethod('info'),
+    warn: buildLogMethod('warn'),
+    error: buildLogMethod('error')
   }
 }
diff --git a/views/index.pug b/views/index.pug
index 5e5303d..fa489f7 100644
--- a/views/index.pug
+++ b/views/index.pug
@@ -2,19 +2,20 @@ html
   head
     title='Moe Counter!'
     meta(name='viewport', content='width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no')
-    link(rel='icon', type='image/png', href='favicon.png')
+    link(rel='icon', type='image/png', href=`${site}/favicon.png`)
     link(rel='stylesheet', href='https://cdn.jsdelivr.net/npm/normalize.css')
     link(rel='stylesheet', href='https://cdn.jsdelivr.net/npm/bamboo.css')
-    link(rel='stylesheet/less', href='style.less')
+    link(rel='stylesheet/less', href=`${site}/style.less`)
     script(less, src='https://cdn.jsdelivr.net/npm/less')
-    <!-- Global site tag (gtag.js) - Google Analytics -->
-    script(async, src='https://www.googletagmanager.com/gtag/js?id=G-2RLWN5JXRL')
+    if ga_id
+      <!-- Global site tag (gtag.js) - Google Analytics -->
+      script(async, src='https://www.googletagmanager.com/gtag/js?id=#{ga_id}')
     script.
       window.dataLayer = window.dataLayer || [];
-      function gtag() {dataLayer.push(arguments); }
+      function gtag() { dataLayer.push(arguments); }
       gtag('js', new Date());
 
-      gtag('config', 'G-2RLWN5JXRL');
+      gtag('config', '#{ga_id}');
 
       function _evt_push(type, category, label) {
         gtag('event', type, {
@@ -148,4 +149,4 @@ html
     div.back-to-top
 
     script(async, src='https://cdn.jsdelivr.net/npm/party-js@2/bundle/party.min.js')
-    script(async, src='script.js')
+    script(async, src=`${site}/script.js`)