button {
  background: none;
  text-decoration: inherit;
  font-family: system-ui;
  font-size: 1rem;
  padding: 1rem 2rem;
}

.border-gradient {
  border: 10px solid;
  border-image-slice: 1;
  border-width: 5px;
}

.border-gradient-purple {
  border-image-source: linear-gradient(to left, #743ad5, #d53a9d);
}

.border-gradient-green {
  border-image-source: linear-gradient(to left, #00C853, #B2FF59);
}

.only-top {
  border-left: 0;
  border-right: 0;
  border-bottom: 0;
}

body {
  height: 100vh;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;
}
body > div {
  width: 100%;
  text-align: center;
}
body > div > div {
  width: 100%;
  padding: 1rem;
}

.on-dark {
  background: #222;
}
.on-dark button {
  color: white;
}