I have a site with an animation that works on all other browsers less than firefoxe, trying to fix it I realized that in my keuframes the update of my css variable is not done as it should, let me explain better the animation is to make the border of a div color as if it was rotating around it, and it is done with this command: border-image: conic-gradient(from var(--angle), #6CC1D7 15%, transparent 19%) 5 5; animation: 5s rotate2 infinite linear ; @keyframes rotate2 { 0%{ --angle:360deg; border-right: 10vmin solid; } 100% { --angle:0deg; border-right: 0vmin solid; } } What's going on, the border-right rule works correctly but the angle is not updated and as a result everything stays put. I couldn't find anything around about this, thanks in advance for the help.