feat: add syntax highlighting and fix code alignment

src/app/post/[slug]/page.tsx

@@ -7,6 +7,7 @@
 import Markdown from "react-markdown";
 import rehypeRaw from "rehype-raw";
 import remarkGfm from "remark-gfm";
+import rehypeHighlight from "rehype-highlight";
 import type { JSX } from "react";
 import { Rule } from "@/components/rule";
 import { getPostData } from "@/lib/posts";
@@ -34,7 +35,7 @@ const Page = async({
       <h2 className="text-center">{post.data.summary}</h2>
       <p className="text-center">{`A ${post.data.readtime}.`}</p>
       <Rule />
-      <Markdown rehypePlugins={[ rehypeRaw ]} remarkPlugins={[ remarkGfm ]}>
+      <Markdown rehypePlugins={[ rehypeRaw, rehypeHighlight ]} remarkPlugins={[ remarkGfm ]}>
         {post.content}
       </Markdown>
       <Rule />