fix katex build error

Author: wenluowang

next.config.js

@@ -1,3 +1,4 @@
+const path = require('path')
 const withNextra = require('nextra')({
   theme: 'nextra-theme-docs',
   themeConfig: './theme.config.jsx'
@@ -15,6 +16,13 @@ module.exports = withNextra({
   basePath,
   assetPrefix: basePath,
   trailingSlash: true,
+  webpack: (config) => {
+    config.resolve.alias['katex/dist/katex.min.css'] = path.join(
+      __dirname,
+      'styles/katex.min.css'
+    )
+    return config
+  },
 })
 
 // If you have other Next.js configurations, you can pass them as the parameter above