Many small adjustments

- Adjust header width for scrollbar presence
- Added new header assets for grass and dirt
- Adjusted styles for hosted and tracker
- Expand header to implement templating system
- Much more I have forgotten

WebHostLib/static/assets/tutorial.js

@@ -44,6 +44,7 @@ window.addEventListener('load', () => {
 
         // Populate page with HTML generated from markdown
         tutorialWrapper.innerHTML += (new showdown.Converter()).makeHtml(results);
+        adjustHeaderWidth();
 
         // Reset the id of all header divs to something nicer
         const headers = Array.from(document.querySelectorAll('h1, h2, h3, h4, h5, h6'));