html, body {
  margin: 0;
  overflow: hidden;
}

.stage {
  box-sizing: border-box;
  min-height: 100vh;
  display: grid;
  place-items: center;
  margin: 0;
  background: #ffffff;
  font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
  padding: clamp(8px, 4vw, 24px);
}

.cm {
  width: 100%;
  max-width: 320px;
  display: grid;
  gap: 20px;
  justify-items: center;
}

.cm__row {
  display: flex;
  align-items: center;
  background: #17141a;
  border-radius: 12px;
  padding: 16px;
  box-sizing: border-box;
  width: 100%;
}

.cm__group {
  position: relative;
  width: 13px;
  height: 20px;
  margin-right: 0;
}
.cm__group--gap {
  margin-left: 8px;
}

.cm__digit,
.cm__mask {
  position: absolute;
  inset: 0;
  display: grid;
  place-items: center;
  font-family: "SFMono-Regular", Consolas, monospace;
  font-weight: 600;
  font-size: 16px;
  color: #fff7e6;
  transition: transform 220ms cubic-bezier(0.2, 0.8, 0.2, 1), opacity 220ms ease-out;
  transition-delay: calc(var(--i, 0) * 45ms);
}

.cm__digit--fixed {
  position: static;
  transition: none;
}

.cm__mask {
  opacity: 0;
  transform: scale(0.4);
}

.cm--masked .cm__digit:not(.cm__digit--fixed) {
  opacity: 0;
  transform: scale(0.4);
}
.cm--masked .cm__mask {
  opacity: 1;
  transform: scale(1);
}

.cm__toggle {
  border: 0;
  border-radius: 999px;
  padding: 8px 20px;
  background: #17141a;
  color: #fff7e6;
  font-weight: 700;
  font-size: 13px;
  cursor: pointer;
  transition: transform 140ms ease-out;
}
.cm__toggle:active {
  transform: scale(0.95);
}
.cm__toggle:focus-visible {
  outline: 2px solid #0a4fe8;
  outline-offset: 2px;
}

@media (max-width: 340px) {
  .cm__row {
    padding: 12px;
  }
  .cm__group {
    width: 11px;
  }
  .cm__digit, .cm__mask {
    font-size: 14px;
  }
}
@media (prefers-reduced-motion: reduce) {
  .cm__digit, .cm__mask {
    transition: none;
    transition-delay: 0ms;
  }
  .cm__toggle {
    transition: none;
  }
}