<label class="tg-flap">
  <input class="tg-flap-input" type="checkbox" checked>
  <span class="tg-flap-stage" aria-hidden="true">
    <span class="tg-flap-row">
      <span class="tg-flap-lbl">Status</span>
      <span class="tg-flap-board">
        <span class="tg-flap-char" data-off="O" data-on="O"></span>
        <span class="tg-flap-char" data-off="F" data-on="N"></span>
        <span class="tg-flap-char" data-off="F" data-on="L"></span>
        <span class="tg-flap-char" data-off="L" data-on="I"></span>
        <span class="tg-flap-char" data-off="I" data-on="N"></span>
        <span class="tg-flap-char" data-off="N" data-on="E"></span>
        <span class="tg-flap-char" data-off="E" data-on="·"></span>
      </span>
    </span>
    <span class="tg-flap-row">
      <span class="tg-flap-lbl">Mode</span>
      <span class="tg-flap-board">
        <span class="tg-flap-char" data-off="S" data-on="A"></span>
        <span class="tg-flap-char" data-off="T" data-on="C"></span>
        <span class="tg-flap-char" data-off="A" data-on="T"></span>
        <span class="tg-flap-char" data-off="N" data-on="I"></span>
        <span class="tg-flap-char" data-off="D" data-on="V"></span>
        <span class="tg-flap-char" data-off="B" data-on="E"></span>
        <span class="tg-flap-char" data-off="Y" data-on="·"></span>
      </span>
    </span>
  </span>
</label>

.tg-flap {
  --tg-flap-bg: #0a0a12;
  --tg-flap-border: #1a1a28;
  --tg-flap-ash: #7a7a98;
  --tg-flap-volt: #e0ff00;
  --tg-flap-ice: #00e5ff;
  --tg-flap-flip: 0.5s;
  display: inline-block;
  cursor: pointer;
  font-family: "Inconsolata", "Roboto Mono", ui-monospace, monospace;
  user-select: none;
}
.tg-flap-input {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0);
  white-space: nowrap; border: 0;
}
.tg-flap-stage {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.tg-flap-row {
  display: flex;
  align-items: center;
  gap: 10px;
}
.tg-flap-lbl {
  min-width: 56px;
  font-size: 12px;
  color: var(--tg-flap-ash);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}
.tg-flap-board {
  display: flex;
  gap: 4px;
}
/* Each char is a black tile with a horizontal seam down the middle and
   a CSS-only flip. The letter is rendered via data-off/data-on attrs in
   a pseudo, so toggling swaps which attr is shown. */
.tg-flap-char {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 38px;
  border-radius: 5px;
  background: var(--tg-flap-bg);
  border: 1px solid var(--tg-flap-border);
  font-size: 18px;
  font-weight: 500;
  color: var(--tg-flap-ash);
  box-shadow:
    inset 0 1px 0 rgba(255,255,255,0.04),
    inset 0 -1px 0 rgba(0,0,0,0.3);
  overflow: hidden;
  transform-style: preserve-3d;
  perspective: 400px;
  transition: color var(--tg-flap-flip) ease;
}
/* Seam across the middle of every char tile. */
.tg-flap-char::after {
  content: "";
  position: absolute;
  left: 0; right: 0;
  top: 50%;
  height: 1px;
  background: rgba(0,0,0,0.6);
  z-index: 2;
  pointer-events: none;
}
/* The letter itself lives in ::before so we can flip it independently
   of the tile chrome. Default shows the off character. */
.tg-flap-char::before {
  content: attr(data-off);
  display: inline-block;
  transform-origin: center;
  animation: tg-flap-off var(--tg-flap-flip) ease both;
}
@keyframes tg-flap-off {
  0%   { transform: rotateX(-90deg); }
  50%  { content: attr(data-off); }
  100% { transform: rotateX(0); }
}
@keyframes tg-flap-on {
  0%   { transform: rotateX(0); }
  50%  { transform: rotateX(-90deg); }
  51%  { transform: rotateX(90deg); }
  100% { transform: rotateX(0); }
}
/* Stagger — each char is delayed 80ms further than the previous so the
   board cascades. Both rows share the same stagger pattern. */
.tg-flap-board .tg-flap-char:nth-child(1) { animation-delay: 0ms; }
.tg-flap-board .tg-flap-char:nth-child(2) { animation-delay: 80ms; }
.tg-flap-board .tg-flap-char:nth-child(3) { animation-delay: 160ms; }
.tg-flap-board .tg-flap-char:nth-child(4) { animation-delay: 240ms; }
.tg-flap-board .tg-flap-char:nth-child(5) { animation-delay: 320ms; }
.tg-flap-board .tg-flap-char:nth-child(6) { animation-delay: 400ms; }
.tg-flap-board .tg-flap-char:nth-child(7) { animation-delay: 480ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-char {
  color: var(--tg-flap-volt);
}
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-row:nth-child(2) .tg-flap-char {
  color: var(--tg-flap-ice);
}
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-char::before {
  content: attr(data-on);
  animation: tg-flap-on var(--tg-flap-flip) ease both;
  animation-delay: inherit;
}
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(1) { animation-delay: 0ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(2) { animation-delay: 80ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(3) { animation-delay: 160ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(4) { animation-delay: 240ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(5) { animation-delay: 320ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(6) { animation-delay: 400ms; }
.tg-flap-input:checked ~ .tg-flap-stage .tg-flap-board .tg-flap-char:nth-child(7) { animation-delay: 480ms; }
.tg-flap-input:focus-visible ~ .tg-flap-stage {
  outline: 2px solid var(--tg-flap-volt);
  outline-offset: 6px;
  border-radius: 6px;
}
@media (prefers-reduced-motion: reduce) {
  .tg-flap-char,
  .tg-flap-char::before { animation: none; transition: none; }
  .tg-flap-char::before { content: attr(data-off); }
  .tg-flap-input:checked ~ .tg-flap-stage .tg-flap-char::before { content: attr(data-on); }
}