Border-Image: Linear Gradient - What each of those declarations means?

I saw an question here with the same problem I was having with my css, which was: I wanted to define my border-left height but border-height doesn't exist on css.

And one of the answers (which solved my problem) was:

table td { border-image: linear-gradient(transparent 10%, blue 10% 90%, transparent 90%) 0 0 0 1 / 3px; }

But I can't understand what all of those means:

• transparent 10%, blue 10% 90%, transparent 90% ?
• 0 0 0 1 ?

I really wanted to understand how it works so I can learn with that and apply it anywhere. Not just ctrl + c and ctrl +v.

Thanks! My first post here.

https://stackoverflow.com/questions/66838061/border-image-linear-gradient-what-each-of-those-declarations-means March 28, 2021 at 11:08AM