:root { color-scheme: dark; }
html, body { height: 100%; margin: 0; }
body {
  background: #000;
  color: #fff;
  display: grid;
  place-items: center;
  font: 16px/1.4 system-ui, -apple-system, "Segoe UI", sans-serif;
}
.gate { position: relative; display: flex; gap: 8px; width: min(320px, calc(100vw - 32px)); }
input {
  flex: 1;
  min-width: 0;
  background: #000;
  color: #fff;
  border: 1px solid #333;
  border-radius: 999px;
  padding: 12px 18px;
  font: inherit;
  outline: none;
  transition: border-color .2s;
}
input:focus { border-color: #888; }
input::placeholder { color: #555; }
button {
  width: 46px;
  flex: none;
  background: #fff;
  color: #000;
  border: 0;
  border-radius: 999px;
  font: inherit;
  font-size: 18px;
  cursor: pointer;
}
button:focus-visible { outline: 2px solid #888; outline-offset: 2px; }
button:disabled { opacity: .5; cursor: default; }
.msg { position: absolute; top: 100%; left: 0; right: 0; margin: 14px 0 0; text-align: center; color: #888; font-size: 14px; min-height: 1.4em; }
.shake { animation: shake .35s; }
@keyframes shake { 20%, 60% { transform: translateX(-8px); } 40%, 80% { transform: translateX(8px); } }
@media (prefers-reduced-motion: reduce) { .shake { animation: none; } }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }