diff --git a/index.html b/index.html
index 977c900..a7f75dc 100644
--- a/index.html
+++ b/index.html
@@ -6,9 +6,12 @@
   <meta name="author" content="sup39">
   <meta name="viewport" content="width=device-width, initial-scale=1.0">
   <link rel="stylesheet" type="text/css" href="https://res.sup39.dev/index.css">
+  <link rel="manifest" href="./manifest.json">
   <style>
-    main {
-      width: fit-content;
+    main, footer {
+      max-width: 480px;
+      margin-left: 0;
+      margin: auto
     }
     #title {
       margin-inline-end: 0em;
@@ -17,7 +20,7 @@
       text-align: end;
     }
     #ct-root span[id] {
-      font-size: 1.5em;
+      font-size: min(3em, 10vw);
       color: #2ee5b8;
       font-weight: bold;
     }
diff --git a/manifest.json b/manifest.json
new file mode 100644
index 0000000..35405cc
--- /dev/null
+++ b/manifest.json
@@ -0,0 +1,5 @@
+{
+  "name": "Countdown | sup39",
+  "short_name": "Countdown",
+  "theme_color": "#2ee5b8"
+}