style: 优化管理后台文章页头部按钮的样式布局

src/routes/admin/posts/[id]/+page.svelte

@@ -458,6 +458,17 @@
 		gap: 10px;
 	}
 
+	.header-actions .btn {
+		display: inline-flex;
+		align-items: center;
+		justify-content: center;
+		box-sizing: border-box;
+		min-height: 42px;
+		margin: 0;
+		line-height: 1;
+		white-space: nowrap;
+	}
+
 	.btn {
 		display: inline-block;
 		padding: 10px 20px;

src/routes/admin/posts/new/+page.svelte

@@ -464,6 +464,17 @@
 		gap: 10px;
 	}
 
+	.header-actions .btn {
+		display: inline-flex;
+		align-items: center;
+		justify-content: center;
+		box-sizing: border-box;
+		min-height: 42px;
+		margin: 0;
+		line-height: 1;
+		white-space: nowrap;
+	}
+
 	.btn {
 		display: inline-block;
 		padding: 10px 20px;