I am not sure if you’ve used Microsoft FrontPage before which was Microsoft’s popular WYSIWYG HTML editor. They’ve replaced it with Office SharePoint Designer which is much better than the FrontPage software.
SharePoint Designer has the rendering engine that is more compliant to the existing web standards so that you can create websites cross browser compatible taking into account all the earlier versions of Microsoft Internet Explorer and other browsers too.
Now Microsoft is giving away SharePoint designer as a free software for download. You just need a LIVE id to sign in and download the software. You can also update it by downloading and installing SharePoint Designer service pack 1.
Please note that this is not to be confused with the SharePoint server software which is for enterprise use and is not free.
Also if you are looking for designing websites and make them cross browser compatible then do also check our article "11 steps to make your website cross browser compatible"