perf: avoid the layout shift for post datetime

_includes/datetime.html

@@ -0,0 +1,21 @@
+<!--
+  Date format snippet
+  See: ${JS_ROOT}/utils/locale-dateime.js
+-->
+
+{% assign wrap_elem = include.wrap | default: 'em' %}
+
+{% if site.prefer_datetime_locale == 'en' or lang == 'en' %}
+  {% assign df_strftime = '%b %e, %Y' %}
+  {% assign df_dayjs = 'll' %}
+{% else %}
+  {% assign df_strftime = '%F' %}
+  {% assign df_dayjs = 'YYYY-MM-DD' %}
+{% endif %}
+
+<{{ wrap_elem }} class="{% if include.class %}{{ include.class }}{% endif %}"
+    data-ts="{{ include.date | date: '%s' }}"
+    data-df="{{ df_dayjs }}"
+    {% if include.tooltip %}data-toggle="tooltip" data-placement="bottom"{% endif %}>
+  {{ include.date | date: df_strftime }}
+</{{ wrap_elem }}>

_includes/related-posts.html

@@ -60,7 +60,6 @@
 {% assign less = TOTAL_SIZE | minus: index_list.size %}
 
 {% if less > 0 %}
-
   {% for i in (0..last_index) %}
     {% assign post = site.posts[i] %}
     {% if post.url != page.url  %}
@@ -74,10 +73,8 @@
       {% endunless %}
     {% endif %}
   {% endfor %}
-
 {% endif %}
 
-
 {% if index_list.size > 0 %}
   <div id="related-posts" class="mt-5 mb-2 mb-sm-4">
     <h3 class="pt-2 mt-1 mb-4 ml-1"
@@ -89,7 +86,7 @@
       <div class="card">
         <a href="{{ post.url | relative_url }}">
           <div class="card-body">
-            {% include timeago.html date=post.date class="small" %}
+            {% include datetime.html date=post.date class="small" %}
             <h3 class="pt-0 mt-1 mb-3" data-toc-skip>{{ post.title }}</h3>
             <div class="text-muted small">
               <p>

_includes/timeago.html

@@ -1,15 +0,0 @@
-<!--
-  Date format snippet
-  See: ${JS_ROOT}/utils/timeago.js
--->
-
-<em class="timeago{% if include.class %} {{ include.class }}{% endif %}"
-    data-ts="{{ include.date | date: '%s' }}"
-    {% if include.tooltip %}
-      data-toggle="tooltip" data-placement="bottom" data-tooltip-df="llll"
-    {% endif %}
-    {% if include.capitalize %}
-      data-capitalize="true"
-    {% endif %}>
-  {{ include.date | date: '%Y-%m-%d' }}
-</em>