diff --git a/package.json b/package.json
index e54ca7033..d13f55bbb 100755
--- a/package.json
+++ b/package.json
@@ -61,6 +61,7 @@
     "@vitejs/plugin-vue": "^1.2.3",
     "@vue/composition-api": "^1.0.0-rc.12",
     "@vueuse/integrations": "^5.0.3",
+    "@windicss/plugin-utils": "^1.1.0",
     "clear-module": "^4.1.1",
     "clipboard": "^2.0.8",
     "color": "^3.1.3",
diff --git a/src/defaultTheme/module.ts b/src/defaultTheme/module.ts
index 7f338dd90..2c9c1a527 100644
--- a/src/defaultTheme/module.ts
+++ b/src/defaultTheme/module.ts
@@ -8,6 +8,7 @@ import { Module, NuxtOptions } from '@nuxt/types'
 import gracefulFs from 'graceful-fs'
 import clearModule from 'clear-module'
 import jiti from 'jiti'
+import { DefaultExtractor } from '@windicss/plugin-utils'
 import defaultWindiConfig from './windi.config'
 
 const r = (...args: string[]) => resolve(__dirname, ...args)
@@ -99,6 +100,24 @@ export default <Module>function themeSetupModule() {
       detect: [...vueFiles, ...mdFiles]
     }
 
+    // extract custom markdown syntax, #503
+    windiOptions.scanOptions.extractors.push({
+      extensions: ['md'],
+      extractor(code, id) {
+        const data = DefaultExtractor(code, id)
+
+        const classes = new Set(data.classes)
+        classes.forEach(i => {
+          if (i.startsWith('.')) classes.add(i.slice(1))
+        })
+
+        return {
+          ...data,
+          classes: Array.from(classes)
+        }
+      }
+    })
+
     // Push every included path into scan options
     windiOptions.scanOptions.include.push(
       join(contentDir, windiGlob),
diff --git a/yarn.lock b/yarn.lock
index 9c0d1de1a..6ea518040 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -111,6 +111,11 @@
   resolved "https://registry.yarnpkg.com/@antfu/utils/-/utils-0.1.7.tgz#ac9e0e62a2490db987c9d8c6b4f38076d763c27f"
   integrity sha512-XbmXbhrjfxQq+ishOKeUIK1VYxQV0B+ZkAQkz00bxhmQd5izdT0YRSDwkyH/KX46gFVBMd+6anvSDlciUt3L4A==
 
+"@antfu/utils@^0.2.2":
+  version "0.2.2"
+  resolved "https://registry.yarnpkg.com/@antfu/utils/-/utils-0.2.2.tgz#b74c5b6f6de64f7e47a669deba054790b26f85d8"
+  integrity sha512-8GwVE0j48SpZaLxsHO0BSO0sEpkb+EhFQcABFBFomH4O8AwNVVvGQNRCBKOPUwU4Vxj3ZSVz8PDjUrPGwaYP9A==
+
 "@babel/code-frame@7.12.11":
   version "7.12.11"
   resolved "https://registry.yarnpkg.com/@babel/code-frame/-/code-frame-7.12.11.tgz#f4ad435aa263db935b8f10f2c552d23fb716a63f"
@@ -2875,6 +2880,19 @@
     micromatch "^4.0.4"
     windicss "^3.1.3"
 
+"@windicss/plugin-utils@^1.1.0":
+  version "1.1.0"
+  resolved "https://registry.yarnpkg.com/@windicss/plugin-utils/-/plugin-utils-1.1.0.tgz#c0834165f40142bf52f24eced1bbf68cbf8bd506"
+  integrity sha512-v9WhtcGKRehsbY2Omd9m+Jd0IsjbKJmRSa712BuPLZ+fZuCSomne9twjqtPn29IGqS6T/9lM8aOjW7mRMU1x/g==
+  dependencies:
+    "@antfu/utils" "^0.2.2"
+    debug "^4.3.2"
+    fast-glob "^3.2.5"
+    jiti "^1.10.1"
+    magic-string "^0.25.7"
+    micromatch "^4.0.4"
+    windicss "^3.1.3"
+
 "@xtuc/ieee754@^1.2.0":
   version "1.2.0"
   resolved "https://registry.yarnpkg.com/@xtuc/ieee754/-/ieee754-1.2.0.tgz#eef014a3145ae477a1cbc00cd1e552336dceb790"