refactor: use "sidebar-tree" for entire rendering

chore: update example site content

chore: add configuration for footer

chore: allow disable footer completely

chore: navbar highlights if contains current page

chore: styling update for partial templates

chore: update steps to use markdown delimiter

exampleSite/content/docs/components/_index.ja.md

@@ -0,0 +1,13 @@
+---
+title: コンポーネント
+weight: 2
+---
+
+Hextraは、[Hugo Shortcodes](https://gohugo.io/content-management/shortcodes/)に基づいたさまざまな組み込みコンポーネントを提供しています。
+
+
+{{< cards >}}
+  {{< card link="callouts" title="Callouts" icon="warning" >}}
+  {{< card link="cards" title="Cards" icon="cards" >}}
+  {{< card link="steps" title="Steps" icon="one" >}}
+{{< /cards >}}

exampleSite/content/docs/components/steps.md

@@ -6,7 +6,7 @@ A built-in component to display a series of steps.
 
 ## Example
 
-{{< steps >}}
+{{% steps %}}
 
 ### Step 1
 
@@ -20,15 +20,15 @@ This is the second step.
 
 This is the third step.
 
-{{< /steps >}}
+{{% /steps %}}
 
 
 ## Usage
 
 Put Markdown h3 header within `steps` shortcode.
 
-```markdown
-{{</* steps */>}}
+```
+{{%/* steps */%}}
 ### Step 1
 
 This is the first step.
@@ -36,5 +36,5 @@ This is the first step.
 ### Step 2
 
 This is the second step.
-{{</* /steps */>}}
+{{%/* /steps */%}}
 ```