Thanks for the detailed description. I'll try to fix it.

If you want to get rid of the file, try to delete this folder:

~/Library/Containers/com.textasticapp.textastic-mac/Data/Library/Saved Application State/com.textasticapp.textastic-mac.savedState/

Deleting this folder should remove all saved window state so that it isn't restored on the next launch of the app.

"header" in your CSS file is not a valid CSS selector since there is no "header" tag in HTML.

If "header" is used in a class attribute in your HTML file, you need to write ".header" instead of "header". If you instead have an HTML element with the id "header", you need to use "#header" as the CSS selector.

Try something like "body" to style the body tag.

It's hard to say what's correct in your case without seeing the rest of your html file.

This is really just basic HTML/CSS, so I'd recommend to have a look at some CSS and HTML tutorials on the web.

Your link tag is wrong. 

Try to replace this line:

<rel="stylesheet" type="text/css" link href="style.css">

with this:

<link rel="stylesheet"  type="text/css" href="style.css">

Also try to run your HTML file through a HTML validator like this: http://validator.w3.org/#validate_by_input. There seem to be some other syntax issues with it.

For example, it should be:

<meta charset="utf-8">

Also, you have a second html tag inside the head section...

This is a problem with Find & Replace on OS X Mavericks. It will be fixed in the next update.

Hello, 

can you please have a look at the "Console" app? Do you see an error message there when this happens? Is there a crash report?

This will be fixed in the next update.

Mavericks changed the behavior of the save panel which caused this issue.

It will be fixed in the next update.

This will be fixed in the next update.