Convert Markdown to HTML with live preview
Headers: # H1 → <h1> | ## H2 → <h2>
# H1
<h1>
## H2
<h2>
Emphasis: **bold** → <strong> | *italic* → <em>
**bold**
<strong>
*italic*
<em>
Lists: - item → <ul> | 1. item → <ol>
- item
<ul>
1. item
<ol>
Code: `inline` → <code> | ```block``` → <pre><code>
`inline`
<code>
```block```
<pre><code>