Added/Improved Formatting for Checkboxes (alshedivat#2191)

A proposed solution for alshedivat#2190. Padding is added such that I considered
it aesthetically pleasing and the bullet points in front of the check
marks were removed.

---------

Co-authored-by: George <31376482+george-gca@users.noreply.github.com>

_posts/2015-03-15-formatting-and-links.md

@@ -11,22 +11,26 @@ Jean shorts raw denim Vice normcore, art party High Life PBR skateboard stumptow
 
 #### Hipster list
 
-<ul>
-    <li>brunch</li>
-    <li>fixie</li>
-    <li>raybans</li>
-    <li>messenger bag</li>
-</ul>
+- brunch
+- fixie
+- raybans
+- messenger bag
+
+#### Check List
+
+- [x] Brush Teeth
+- [ ] Put on socks
+  - [x] Put on left sock
+  - [ ] Put on right sock
+- [x] Go to school
 
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 <hr>
 
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-<blockquote>
-    We do not grow absolutely, chronologically. We grow sometimes in one dimension, and not in another, unevenly. We grow partially. We are relative. We are mature in one realm, childish in another.
-    —Anais Nin
-</blockquote>
+> We do not grow absolutely, chronologically. We grow sometimes in one dimension, and not in another, unevenly. We grow partially. We are relative. We are mature in one realm, childish in another.
+> —Anais Nin
 
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_sass/_base.scss

@@ -127,6 +127,22 @@ blockquote {
   }
 }
 
+// Checklist
+
+ul.task-list {
+  list-style-type: none; /* Remove bullets from all levels */
+}
+
+ul.task-list > li ul {
+  /* Nested lists within .task-list */
+  padding-inline-start: 1.5rem;
+}
+
+ul.task-list input[type="checkbox"] {
+  margin: 0.275rem 0.5rem 0.5rem -1rem;
+  vertical-align: middle;
+}
+
 // Math
 
 .equation {