diff --git a/nuxt.config.js b/nuxt.config.js
index 95910cb..190c948 100644
--- a/nuxt.config.js
+++ b/nuxt.config.js
@@ -24,6 +24,7 @@ module.exports = {
     { src: '~/plugins/element-ui', ssr: false },
     { src: '~/plugins/vue-gtag.js', ssr: false, mode: 'client' },
     { src: '~/plugins/vue-sanitize', ssr: false },
+    { src: '~/plugins/directives', ssr: false },
   ],
 
   // Auto import components: https://go.nuxtjs.dev/config-components
diff --git a/plugins/directives.js b/plugins/directives.js
new file mode 100644
index 0000000..8b2857d
--- /dev/null
+++ b/plugins/directives.js
@@ -0,0 +1,7 @@
+import Vue from 'vue'
+
+Vue.directive('fcf', {
+  inserted(el) {
+    el.innerHTML = el.innerHTML.replace(/(\d+)/g, `<sub>$1</sub>`)
+  },
+})