<fieldset class="crb-push">
  <legend class="crb-sr">Difficulty</legend>
  <label><input type="radio" name="crb-push" /><span>Easy</span></label>
  <label><input type="radio" name="crb-push" checked /><span>Hard</span></label>
  <label><input type="radio" name="crb-push" /><span>Expert</span></label>
</fieldset>

.crb-push { display: flex; gap: 8px; border: 0; padding: 0; }
.crb-push input { appearance: none; -webkit-appearance: none; position: absolute; opacity: 0; }
.crb-push label { cursor: pointer; }
.crb-push span {
  display: block; padding: 10px 18px;
  background: linear-gradient(180deg, #2a2a3e, #1a1a28);
  color: #cbd5e1; font: 600 12px/1 system-ui, sans-serif;
  border-radius: 8px;
  box-shadow: 0 3px 0 #0c0c12, inset 0 1px 0 rgba(255,255,255,0.06);
  transform: translateY(0);
  transition: transform 0.12s, box-shadow 0.12s, color 0.2s, background 0.25s;
}
.crb-push input:checked + span {
  transform: translateY(3px);
  background: linear-gradient(180deg, #1a1a28, #0c0c12);
  color: #a78bfa;
  box-shadow: 0 0 0 #0c0c12, inset 0 2px 6px rgba(0,0,0,0.5), inset 0 0 0 1px rgba(124,108,255,0.3);
}

.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;
}