Add subtitles support

Fixes #3

_includes/page_header.html

@@ -12,5 +12,8 @@
   {% if meta != "" %}
     <p class="meta">{{ meta }}</p>
   {% endif %}
-  <h1 class="page-header__title">{{ page.title }}</h1>
+  <h1>{{ page.title }}</h1>
+  {% if page.subtitle %}
+    <p class="lead">{{ page.subtitle }}</p>
+  {% endif %}
 </header>

_posts/2019-09-09-subtitles.md

@@ -0,0 +1,32 @@
+---
+subtitle: Posts can have subtitles, which appear in large text beneath the title. "Lead" paragraphs also use the same large text style.
+---
+
+Subtitles and Lead Paragraphs
+=============================
+
+To give a post a subtitle by add a `subtitle` to its [YAML front matter](https://jekyllrb.com/docs/front-matter/):
+
+```yaml
+---
+title: Subtitles and Lead Paragraphs
+subtitle: Posts can have subtitles, which appear in large text beneath the title.
+---
+```
+
+Subtitles appear beneath the title at the top of the page, in large text.
+
+You can also use this large text style anywhere in a page by creating a
+paragraph with the CSS class `lead`. For example this:
+
+```html
+<p class="lead">This is a "lead" paragraph. It stands out more than other
+paragraphs. These can go anywhere on the page, not just at the top of
+posts.</p>
+```
+
+Will render like this:
+
+<p class="lead">This is a "lead" paragraph. It stands out more than other
+paragraphs. These can go anywhere on the page, not just at the top of
+posts.</p>

_sass/_layout.scss

@@ -90,7 +90,6 @@ body {
 
 .page-header {
   padding-top: 50px;
-  padding-bottom: 45px;
 }
 
 .inner-container {
@@ -99,10 +98,6 @@ body {
   margin-right: auto;
 }
 
-.page-header__title {
-  margin-bottom: 0;
-}
-
 .content .posts-list {
   list-style-type: none;
 }

index.md

@@ -20,7 +20,7 @@ and lots of typographical extras like
 [footnotes](_posts/2019-08-06-footnotes.md),
 [emoji](_posts/2019-08-11-emoji.md),
 [alerts](_posts/2019-09-09-alert-boxes.md),
-[lead paragraphs](_posts/2019-09-09-lead-paragraphs.md),
+[subtitles](_posts/2019-09-09-subtitles.md),
 [badges](_posts/2019-09-13-badges-and-pills.md)
 and more.