Fix template markup (#5383)

stewart/parts/header-title-nav.html

@@ -1,5 +1,5 @@
 <!-- wp:group {"align":"full","layout":{"inherit":true}} -->
-<div class="wp-block-group alignfull"><!-- wp:group {"align":"wide","style":{"spacing":{"padding":{"top":"var(-d-dwp-d-dcustom-d-dmargin-d-dhorizontal, 30px)","bottom":"40px"}}},"layout":{"type":"flex","justifyContent":"space-between"}} -->
+<div class="wp-block-group alignfull"><!-- wp:group {"align":"wide","style":{"spacing":{"padding":{"top":"var(--wp--custom--margin--horizontal, 30px)","bottom":"40px"}}},"layout":{"type":"flex","justifyContent":"space-between"}} -->
 <div class="wp-block-group alignwide" style="padding-top:var(--wp--custom--margin--horizontal, 30px);padding-bottom:40px"><!-- wp:group {"layout":{"type":"flex"}} -->
 <div class="wp-block-group"><!-- wp:site-logo {"width":64} /-->