<fieldset class="crb-pill">
  <legend class="crb-sr">Billing</legend>
  <input type="radio" name="crb-pill" id="crb-pill-1" checked />
  <label for="crb-pill-1">Monthly</label>
  <input type="radio" name="crb-pill" id="crb-pill-2" />
  <label for="crb-pill-2">Yearly</label>
  <input type="radio" name="crb-pill" id="crb-pill-3" />
  <label for="crb-pill-3">Forever</label>
  <span class="crb-pill-thumb"></span>
</fieldset>

.crb-pill {
  display: inline-flex; position: relative; padding: 4px;
  background: #1a1a28; border: 1px solid rgba(255,255,255,0.08);
  border-radius: 999px;
}
.crb-pill input { appearance: none; -webkit-appearance: none; position: absolute; opacity: 0; }
.crb-pill label {
  flex: 1 1 0; min-width: 80px;
  position: relative; z-index: 1;
  padding: 8px 16px;
  font: 600 12px/1 system-ui, sans-serif; color: #b8b6d4;
  text-align: center;
  cursor: pointer; transition: color 0.25s;
  border-radius: 999px;
}
.crb-pill input:checked + label { color: #fff; }
.crb-pill-thumb {
  position: absolute; top: 4px; bottom: 4px; left: 4px;
  width: calc(33.333% - 2.667px);
  background: linear-gradient(135deg, #7c6cff, #a78bfa);
  border-radius: 999px; z-index: 0;
  transition: transform 0.4s cubic-bezier(0.65,0,0.35,1);
}
#crb-pill-2:checked ~ .crb-pill-thumb { transform: translateX(100%); }
#crb-pill-3:checked ~ .crb-pill-thumb { transform: translateX(200%); }

.crb-sr {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}