Gradient Border

A gradient border rotates around the button.

.gbtn { position:relative; padding:14px 28px; background:#0a0a0b; color:white; border:none; border-radius:10px; cursor:pointer; z-index:1; }
.gbtn::before { content:""; position:absolute; inset:-2px; border-radius:12px; background:conic-gradient(#8b5cf6,#ec4899,#f59e0b,#8b5cf6); z-index:-1; animation:spin 3s linear infinite; }
@keyframes spin { to { transform:rotate(360deg); } }