BLOG-87 Fix to unify post content title color (#88)

### Description

- Enhance typography and color consistency in PostPreview and PostContentPage
- Add tailwind configuration for custom typography styles

### Package Changes

_No response_

### Screenshots

_No response_

### Reference

Resolves #87

### Checklist

- [x] A milestone is set
- [x] The related issuse has been linked to this branch

Reviewed-on: #88
Co-authored-by: SquidSpirit <squid@squidspirit.com>
Co-committed-by: SquidSpirit <squid@squidspirit.com>

frontend/src/app.css

@@ -1,5 +1,6 @@
 @import 'tailwindcss';
 @plugin '@tailwindcss/typography';
+@config "../tailwind.config.js";
 
 @font-face {
 	font-family: 'HackNerdMono';

frontend/src/lib/post/framework/ui/PostContentPage.svelte

@@ -16,7 +16,7 @@
 	onMount(() => postBloc.dispatch({ event: PostEventType.PostLoadedEvent, id: id }));
 </script>
 
-<article class="container prose pb-10">
+<article class="container prose pb-10 prose-gray">
 	{#if state.data}
 		<PostContentHeader postInfo={state.data.info} />
 		<div class="max-w-3xl">

frontend/src/lib/post/framework/ui/PostPreview.svelte

@@ -34,7 +34,7 @@
 	</div>
 	<div class="flex flex-col gap-y-2.5">
 		<PostPreviewLabels labels={postInfo.labels} />
-		<span class="line-clamp-1 text-lg font-bold">{postInfo.title}</span>
+		<span class="line-clamp-1 text-lg font-bold text-gray-800">{postInfo.title}</span>
 		<span class="line-clamp-3 text-justify text-sm">{postInfo.description}</span>
 		<span class="text-sm text-gray-500">{postInfo.formattedPublishedTime}</span>
 	</div>

frontend/tailwind.config.js

@@ -0,0 +1,18 @@
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+	theme: {
+		extend: {
+			typography: () => ({
+				gray: {
+					css: {
+						'--tw-prose-body': 'var(--color-gray-700)',
+						'--tw-prose-headings': 'var(--color-gray-800)',
+						'--tw-prose-links': 'var(--color-gray-800)',
+						'--tw-prose-bold': 'var(--color-gray-800)',
+						'--tw-prose-quotes': 'var(--color-gray-800)'
+					}
+				}
+			})
+		}
+	}
+};