I love it when I come across some bit of CSS I’ve never heard of before.

Take this article on the text-emphasis property.

“The what property?”, I hear you ask. That was my reaction too. But look, it’s totally a thing.

Or take this article by David Bushell called CSS Button Styles You Might Not Know.

Sure enough, halfway through the article David starts talking about styling the button in an input type="file” using the ::file-selector-button pseudo-element:

All modern browsers support it. I had no idea myself until recently.

He’s right!

Then I remembered that I’ve got a file upload input in the form I use for posting my notes here on adactio.com (in case I want to add a photo). I immediately opened up my style sheet, eager to use this new-to-me bit of CSS.

I found the bit where I style buttons and this is the selector I saw:

button,
input[type="submit"],
::file-selector-button

Huh. I guess I did know about that pseudo-element after all. Clearly the knowledge exited my brain shortly afterwards.

There’s that tautological cryptic saying, “You don’t know what you don’t know.” But I don’t even know what I do know!

@adactio Just this morning I stumbled across the sepia() filter. Mind blown.

@baldur this happens to me in my job as a developer on a daily basis but on a much larger scale. I have added whole features to my services or apps and then completely forgotten them, to the point that I’ll go to add a cool new bit of functionality only to see it sitting there waiting for me to discover. A gift from my younger self.