.block-with-border

html,
body {
  padding: 0;
  margin: 0;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
}

.block-with-border {
  position: relative;
  width: 300px;

  &::before {
    content: "";
    display: block;
    height: 1px;
    background: radial-gradient(circle at center, gray, transparent);
  }
}