gradiente linear de base e imagem e raio de borda
.rounded-corners-gradient-borders {
width: 300px;
height: 80px;
border: double 4px transparent;
border-radius: 80px;
background-image: linear-gradient(white, white), radial-gradient(circle at top left, #f00,#3020ff);
background-origin: border-box;
background-clip: content-box, border-box;
}
Sergiu The Man