SLlirik

<div class="box"></div>


.box {
    position: relative;
    width: 150px;
    height: 150px;
    border-radius: 50%;
}

.box::before {	
    --border-width: 10px;   /*Ширина границы*/
    content: '';
    position: absolute;
    inset: calc(0px - var(--border-width));
    z-index: -1;
   
   	/*
   	если нет поддержки inset:
   	top: var(--border-width);
   	left: var(--border-width);
  	right: var(--border-width);
   	bottom: var(--border-width);
   	*/
   	
    padding: var(--border-width);
    border-radius: inherit;
    background: linear-gradient(45deg, yellowgreen, orangered);
    -webkit-mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    mask: linear-gradient(#fff 0 0) content-box, linear-gradient(#fff 0 0);
    -webkit-mask-composite: xor;
    mask-composite: exclude;
}