Different browsers show webpages differently. After you have done this for a short period of time, you'll find out that any mistakes you make, show up on different browsers.

If you want to experiment with this, there is a HTML kit that can be downloaded for free at

http://www.download.com/HTML-Kit/3000-2048_4-4687625.html

Make sure to go to

http://www.chami.com/html-kit/plugins/

and get the HTML tidy plugin. The html kit will allow you to change and edit everything while offline. Using the plugin html tidy, help you to correct your mistakes. It will even let you change the color of your fonts.

Another thing would be is to go to

http://www.mozilla.org/

and download the Mozilla Firefox browser. Then get the extention called Html Validator 0.7.1

You can get the extention at

https://addons.mozilla.org/quicksearch.php?q=html+validator&section=A

You click on view source and the validator will chow you the source. Then if you click on clean up this page, It will also help you clean it up. However if you have made any mistakes, don't expect the page to look correct. before you do this I would reccommend you copy the html code and paste it to notepad. That way you have your origional code to fall back on. It may take you a few times until you get this correct, but then here is the real test.

Go to

http://validator.w3.org/

and type in your url. It will tell you all the mistakes and give you information.

Hope this helps.