I deal with many people who work with Windows XP (Unfortunately). But Windows XP’s last supported Internet Explorer was IE8. And, unfortunately, I have to add code to attempt to make pages IE8 compatible.
But I make no effort to make pages IE7 compatible and, if I do so, it almost always causes issues with the modern browsers. For instance, removing block will bring back spacing problems.
In the height if its popularity, IE7 web pages were still being built using a lot of table layouts. It never supported a single line of HTML5 or CSS3 and most modern code has both in it. With so few people in the world using IE7, I would advice that no amount of effort put towards it is a good investment. Microsoft and all web companies agree with me. That’s what I mean when I say, “not supported.” Microsoft and the industry in general has abandoned it and long ago made announcements that they will in no way support the IE7 platform nor attempt to make web sites work with it. More recently, most companies did the same with IE8.
Attempting to support extremely outdated browsers is a ton of effort to support perhaps 1% of the internet public. It is much more cost-effective to simply tell that 1% that the issues they see are their fault. You don’t see Nintendo making Wii U games compatible with the Nintendo 64. That’s the same number of generations back as IE7.