refactor: 调整文章详情页封面图的显示位置

src/routes/posts/[slug]/+page.svelte

@@ -63,11 +63,6 @@
 <main id="pjax-container">
 	<div class="wrapper container narrow contents-wrap">
 		<article class="article-detail yue">
-			{#if data.post.cover}
-				<div class="post-cover detail-cover">
-					<img src={data.post.cover} alt={data.post.title} />
-				</div>
-			{/if}
 			<div class="banner-title">
 				<h1 class="post-title">{data.post.title}</h1>
 				<p class="post-meta">
@@ -75,6 +70,11 @@
 					<time>{data.post.date}</time>
 				</p>
 			</div>
+			{#if data.post.cover}
+				<div class="post-cover detail-cover">
+					<img src={data.post.cover} alt={data.post.title} />
+				</div>
+			{/if}
 			
 			<MarkdownRenderer content={data.post.content} />