Single post in Guide to CSS: Beginner to Expert

Making them perfectly square could get a little tricky. If your ultimate goal is to have images, icons, or emojis as tabs, it might be easy. Then you could just set fixed heights and widths to match the images, and use flex to space them evenly on large and small screens. But if you're putting text in the tab headers, unless you're very careful you could make the tabs look odd or be hard to use on some devices... you could get weird text overflow issues, and tabs that don't fit correctly on mobile. There may be ways around this, especially if it's your own signature and you know exactly what you're going to put in the tabs. But if it's for others, I'm not sure. (Side note: If this was a post template instead of a signature you might have more options... it's not always ideal but at least you have relatively unlimited vertical space, so if your tabs wrap to a second row it doesn't matter as much. But for a signature, if your tabs are tall since they're squares, and wrap to a new line, they could push all the content right out of the view window)