style: enhance Header component and update SCSS imports

- Improved the Header component by adding a site title with styling.
- Wrapped navigation links in a div for better structure.
- Updated SCSS imports across multiple components for consistency.

src/components/PostSummary.astro

@@ -12,7 +12,7 @@ const formattedDate = dayjs(post.data.pubDate.toString()).format("MMMM DD, YYYY"
 ---
 
 <style lang="scss">
-        @use "../scss/variables" as *;
+	@use "../scss/variables" as *;
 
 	a {
 		color: $colorText;