chore: extract style and component updates from BitcoinDesign#20

@GBKS getting started pr contains updates to styles that would be used by other writers - while that pr is under review this PR extracts those styles so they can be available to new contributors

_includes/image.html

@@ -6,5 +6,5 @@
     	width="{{ include.width }}" 
     	height="{{ include.height }}"
     >
-    {% if include.caption %}<figcaption class="small">{{ include.caption }}</figcaption>{% endif %}
+    {% if include.caption %}<figcaption markdown="1">{{ include.caption | markdownify }}</figcaption>{% endif %}
 </figure>

_includes/picture.html

@@ -18,5 +18,5 @@
 	    	height="{{ include.height }}"
 	    >
 	</picture>
-	{% if include.caption %}<figcaption class="small">{{ include.caption }}</figcaption>{% endif %}
+	{% if include.caption %}<figcaption markdown="1">{{ include.caption | markdownify }}</figcaption>{% endif %}
 </figure>

_sass/minima/_nav-list.scss

@@ -16,16 +16,25 @@
     position: relative;
     margin: 0;
 
-    .nav-list-link {
+    a.nav-list-link {
       display: block;
       font-size: 15px;
       line-height: 34px;
       margin-left: 34px;
+      color: black;
+
+      &:visited {
+        color: black;
+      }
 
       &.-active {
         font-weight: 500;
         color: $primary-color;
         text-decoration: none;
+
+        &:visited {
+          color: $primary-color;
+        }
       }
 
       &:hover,
@@ -82,13 +91,19 @@
     }
 
     &.-active {
-      > .nav-list-link {
-          // color: $primary-color;
+      > a.nav-list-link {
+          color: $primary-color;
+
+          &:visited {
+            color: $primary-color;
+          }
       }
 
-      > .nav-list-expander svg {
-          transform: rotate(90deg);
-          color: $primary-color;
+      > .nav-list-expander {
+          svg {
+            transform: rotate(90deg);
+            color: $primary-color;
+          }
       }
 
       > .nav-list {