enhance newsletter form default UI

assets/css/extended/newsletter.scss

@@ -324,6 +324,7 @@ body.type-newsletter.kind-page {
     padding: var(--content-gap) var(--gap);
     .notice {
       font-size: .9em;
+      font-weight: bold;
       color: var(--signature);
       line-height: 1.6;
     }

layouts/_default/single.html

@@ -56,8 +56,11 @@
     {{- if $isNewsletter }}
       <div class="newsletter-sub">
         <div class="notice">
-          <div style="font-weight: bold">Thanks for reading, if you like it, please subscribe below.</div>
-          <div style="font-size: .85em; margin-top: 8px;">感谢你能读到这里，如果觉得有趣的话，欢迎在下方输入邮箱进行订阅。</div>
+          {{- if site.Params.newsletter.notice.usePartial }}
+            {{- partial "newsletter_notice.html"}}
+          {{- else }}
+            {{- site.Params.newsletter.notice.content | default "Thanks for reading, if you like it, please subscribe below." }}
+          {{- end }}
         </div>
         {{- partial "newsletter_sub_form.html"}}
       </div>

layouts/partials/newsletter_sub_form.html

@@ -7,7 +7,7 @@
     <div class="input-group">
       <input type="text" name="email" placeholder="Your email address">
 
-      <button type="submit">Subscribe<span class="hide-for-sm"> | 订阅</span></button>
+      <button type="submit">Subscribe</span></button>
     </div>
 
   </form>