<button class="btn-12"><span>Button</span></button>

<style>
/* From Uiverse.io by doniaskima - Tags: button */
.btn-12,
.btn-12 *,
.btn-12 :after,
.btn-12 :before,
.btn-12:after,
.btn-12:before {
  border: 0 solid;
  box-sizing: border-box;
}

.btn-12 {
  -webkit-tap-highlight-color: transparent;
  -webkit-appearance: button;
  background-color: #000;
  background-image: none;
  color: #fff;
  cursor: pointer;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont,
    Segoe UI, Roboto,