.box{position:relative;--mask:radial-gradient(30px at 30px 30px,#0000 calc(98% - 7px),#000 calc(100% - 7px) 98%,#0000) -30px -30px,linear-gradient(90deg,#000 14px,#0000 0) -7px 50% /100% calc(100% - 60px + 7px) repeat-x,linear-gradient(#000 14px,#0000 0) 50% -7px /calc(100% - 60px + 7px) 100% repeat-y}.box:before{content:"";position:absolute;inset:0;background:#000;-webkit-mask:var(--mask);mask:var(--mask)}.gradient-box{position:relative;padding:2px;box-sizing:border-box;color:#fff;background:#000;background-clip:padding-box;
  /* !importanté */border:5px solid transparent;
  /* !importanté */border-radius:6px}.gradient-box:before{content:"";position:absolute;top:0;right:0;bottom:0;left:0;margin:-5px;
  /* !importanté */border-radius:inherit;
  /* !importanté */background:linear-gradient(180deg,#7dd3fc,#0369a1)}