canvas{--angle: 0deg;border:15px solid;border-image:conic-gradient(from var(--angle),red,yellow,lime,aqua,blue,magenta,red) 1;border-image-slice:1;animation:10s rotate linear infinite}@keyframes rotate{to{--angle: 360deg}}h1,p{font-size:24px;text-align:center}div{display:flex;justify-content:center}@property --angle{syntax: "<angle>"; initial-value: 0deg; inherits: false;}