Check your code here : W3C.org Who make the rules, standards and practices for web code. HTML https://validator.w3.org/ CSS https://jigsaw.w3.org/css-validator/ and https://validator.w3.org/i18n-checker/ and http://mobile.css-validator.org/ Plus have a Editor free : https://www.w3.org/Amaya/ Free : http://bluegriffon.org/ think still free , Built on Firefox http://www.kompozer.net/ free Probably save the files then open them with Firefox. I never used the preview as best to save or loose it. No idea of the limitations of your program. Should save outside of the program all your files in a Folder so you can just open the folder and drag and drop it into the browser. Only way is to get a 64 bit WYSIWYG Webbuilder Hope not paying..... No there will be no fixes, you can downgrade to 32bit Firefox https://www.mozilla.org/en-US/firefox/all/ but why bother when there are tons of free stuff Just google the 1 name have provided and there is a list of programs with icons that are all reputable. Only download from their home sites. Seamonkey is a Browser based on Firefox and was part of Mozilla till late this year, it has a HTML Editor also. I do not like the code myself it puts out. All code should pass the URL's Provided above and your page will display on any browser and look the same. Also Google likes good code for page ranking. Get a Google Webmaster account, free when ready to go for it. Please let us know if this solved your issue or if need further assistance.