Update post styles for improved readability and aesthetics

- Increased the font size of post titles (h1) from 3xl to 4xl and changed the color to white for better visibility.
- Updated the color of inline code snippets from red to purple for enhanced contrast and visual appeal.

src/styles/post.css

@@ -11,7 +11,7 @@
 }
 
 .post h1 {
-  @apply mt-8 text-3xl text-slate-400;
+  @apply mt-8 text-4xl text-white;
 }
 
 .post h2 {
@@ -23,7 +23,7 @@
 }
 
 .post code {
-  @apply rounded-sm bg-neutral-800 px-1 py-[2px] text-red-500;
+  @apply rounded-sm bg-neutral-800 px-1 py-[2px] text-purple-400;
 }
 
 .post a {