:root {
  color-scheme: dark;
  --ink: #effbff;
  --muted: #9abdc9;
  --panel: #102e3b;
  --panel-deep: #0a202b;
  --line: rgba(171, 231, 245, 0.2);
  --cyan: #a7e9f3;
  --pink: #f8b0cc;
  --yellow: #ffdb8b;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-width: 320px;
  min-height: 100vh;
  overflow-x: hidden;
  background:
    radial-gradient(circle at 50% -10%, rgba(74, 172, 207, 0.28), transparent 44%),
    #081a24;
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

button,
a {
  font: inherit;
}

button {
  cursor: pointer;
}

.shell {
  display: grid;
  min-height: 100vh;
  place-items: center;
  padding: 26px 16px;
}

.game {
  position: relative;
  width: min(100%, 540px);
  min-height: 720px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 30px;
  background: linear-gradient(145deg, rgba(22, 60, 75, 0.97), rgba(7, 24, 33, 0.99));
  box-shadow: 0 28px 80px rgba(0, 0, 0, 0.34);
}

.topbar,
.scorebar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 22px;
  color: var(--muted);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.topbar strong {
  color: var(--cyan);
  font-size: 0.68rem;
}

.back-link,
.hub-link {
  color: var(--muted);
  text-decoration: none;
}

.back-link:hover,
.hub-link:hover {
  color: var(--ink);
}

.scorebar {
  gap: 14px;
  justify-content: flex-start;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.scorebar span {
  display: grid;
  gap: 5px;
  min-width: 104px;
}

.scorebar small {
  color: var(--muted);
  font-size: 0.63rem;
}

.scorebar strong {
  color: var(--ink);
  font-size: 1.04rem;
  letter-spacing: 0.08em;
}

.signal-panel {
  padding: 28px 22px 0;
  text-align: center;
}

.kicker {
  margin: 0 0 12px;
  color: var(--cyan);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

h1,
h2 {
  margin: 0 auto;
  max-width: 12ch;
  color: var(--ink);
  font-size: clamp(2.35rem, 10vw, 3.5rem);
  letter-spacing: -0.08em;
  line-height: 0.95;
}

h1 em,
h2 em {
  color: var(--pink);
  font-family: Georgia, serif;
  font-weight: 400;
}

.signal {
  --signal-hue: 190;
  --signal-saturation: 65%;
  --signal-lightness: 64%;
  --signal-tilt: 0deg;
  --signal-line: 50%;
  --signal-density: 10px;
  position: relative;
  overflow: hidden;
  isolation: isolate;
  background:
    radial-gradient(circle at 78% 20%, hsla(var(--signal-hue), 95%, 88%, 0.82), transparent 29%),
    linear-gradient(145deg,
      hsl(var(--signal-hue), var(--signal-saturation), calc(var(--signal-lightness) + 8%)),
      hsl(calc(var(--signal-hue) + 24), var(--signal-saturation), calc(var(--signal-lightness) - 22%)));
}

.signal::before {
  position: absolute;
  inset: -30%;
  z-index: -1;
  background: repeating-linear-gradient(
    calc(82deg + var(--signal-tilt)),
    transparent 0 var(--signal-density),
    rgba(255, 255, 255, 0.24) calc(var(--signal-density) + 1px),
    transparent calc(var(--signal-density) + 3px)
  );
  content: "";
  opacity: 0.7;
  transform: translateX(var(--signal-shift, 0px));
}

.signal::after {
  position: absolute;
  top: var(--signal-line);
  right: -8%;
  left: -8%;
  height: 28px;
  border-top: 2px solid rgba(255, 255, 255, 0.74);
  background: repeating-linear-gradient(
    90deg,
    transparent 0 20px,
    rgba(255, 255, 255, 0.3) 21px 23px,
    transparent 24px 38px
  );
  content: "";
  opacity: 0.62;
  transform: rotate(var(--signal-tilt));
}

.signal--target {
  width: 100%;
  height: 132px;
  margin: 25px auto 0;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 22px;
  box-shadow: 0 16px 34px rgba(0, 0, 0, 0.2), inset 0 0 30px rgba(255, 255, 255, 0.12);
}

.signal--target::before {
  animation: scan-drift 4.8s linear infinite;
}

.signal--target::after {
  animation: pulse-line 2.4s ease-in-out infinite;
}

.target-caption {
  margin: 14px auto 0;
  max-width: 38ch;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.45;
}

.status {
  min-height: 21px;
  margin: 14px 0 0;
  color: var(--cyan);
  font-size: 0.82rem;
}

.choice-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 10px;
  padding: 22px;
}

.choice {
  position: relative;
  aspect-ratio: 1.18;
  overflow: hidden;
  padding: 0;
  border: 1px solid rgba(171, 231, 245, 0.23);
  border-radius: 15px;
  background: var(--panel-deep);
  box-shadow: inset 0 0 0 1px rgba(255, 255, 255, 0.03);
  transition: border-color 160ms ease, box-shadow 160ms ease, transform 160ms ease;
}

.choice:hover {
  border-color: var(--cyan);
  box-shadow: 0 8px 24px rgba(96, 190, 213, 0.15);
  transform: translateY(-2px);
}

.signal--choice {
  position: absolute;
  inset: 0;
}

.choice-number {
  position: absolute;
  right: 7px;
  bottom: 6px;
  z-index: 1;
  color: rgba(255, 255, 255, 0.74);
  font-size: 0.62rem;
  letter-spacing: 0.08em;
}

.choice.is-correct {
  border-color: var(--cyan);
  box-shadow: 0 0 0 2px rgba(167, 233, 243, 0.25), 0 0 28px rgba(167, 233, 243, 0.3);
  animation: correct-pop 420ms ease;
}

.choice.is-wrong {
  border-color: var(--pink);
  box-shadow: 0 0 0 2px rgba(248, 176, 204, 0.2);
  animation: wrong-shake 320ms ease;
}

.footnote {
  margin: -5px 22px 26px;
  color: rgba(154, 189, 201, 0.72);
  font-size: 0.68rem;
  text-align: center;
}

.overlay {
  position: absolute;
  inset: 0;
  z-index: 2;
  display: grid;
  place-items: center;
  padding: 28px;
  background: rgba(5, 18, 26, 0.86);
  opacity: 0;
  pointer-events: none;
  transition: opacity 180ms ease;
}

.overlay--visible {
  opacity: 1;
  pointer-events: auto;
}

.card {
  width: min(100%, 370px);
  padding: 34px 28px 30px;
  border: 1px solid rgba(167, 233, 243, 0.24);
  border-radius: 24px;
  background: linear-gradient(145deg, #1a4a5a, #102b39);
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.36);
  text-align: center;
}

.hero-scan {
  position: relative;
  display: grid;
  width: 130px;
  height: 72px;
  margin: 0 auto 26px;
  place-items: center;
  border: 1px solid rgba(167, 233, 243, 0.34);
  border-radius: 50%;
  background: radial-gradient(circle, rgba(167, 233, 243, 0.27), transparent 60%);
  transform: rotate(-5deg);
}

.hero-scan span,
.hero-scan i,
.hero-scan b {
  position: absolute;
  display: block;
  border: 1px solid rgba(167, 233, 243, 0.52);
  border-radius: 50%;
}

.hero-scan span { width: 90px; height: 43px; }
.hero-scan i { width: 56px; height: 27px; }
.hero-scan b { width: 18px; height: 9px; background: var(--pink); box-shadow: 0 0 20px rgba(248, 176, 204, 0.6); }

.card p:not(.kicker) {
  margin: 22px auto 26px;
  max-width: 31ch;
  color: var(--muted);
  line-height: 1.55;
}

.card > small {
  display: block;
  margin-top: 14px;
  color: var(--muted);
  font-size: 0.72rem;
}

.primary {
  width: 100%;
  border: 1px solid var(--cyan);
  border-radius: 999px;
  padding: 14px 18px;
  background: var(--cyan);
  color: #143744;
  font-weight: 800;
  transition: transform 160ms ease, box-shadow 160ms ease;
}

.primary:hover {
  box-shadow: 0 10px 30px rgba(167, 233, 243, 0.18);
  transform: translateY(-2px);
}

.hub-link {
  display: block;
  margin-top: 26px;
  font-size: 0.78rem;
}

.seal {
  display: grid;
  width: 54px;
  height: 54px;
  margin: 0 auto 22px;
  place-items: center;
  border: 1px solid var(--cyan);
  border-radius: 50%;
  color: var(--cyan);
  font-size: 1.45rem;
}

.result {
  display: flex;
  justify-content: center;
  gap: 26px;
  margin: 4px 0 24px;
  color: var(--muted);
  font-size: 0.68rem;
  letter-spacing: 0.13em;
}

.result b {
  display: block;
  margin-top: 6px;
  color: var(--yellow);
  font-size: 1.1rem;
  letter-spacing: 0.08em;
}

@keyframes scan-drift {
  from { transform: translateX(-2%) rotate(0deg); }
  to { transform: translateX(2%) rotate(1deg); }
}

@keyframes pulse-line {
  0%, 100% { opacity: 0.42; transform: rotate(var(--signal-tilt)) scaleX(0.96); }
  50% { opacity: 0.82; transform: rotate(var(--signal-tilt)) scaleX(1.02); }
}

@keyframes correct-pop {
  0%, 100% { transform: scale(1); }
  45% { transform: scale(1.05); }
}

@keyframes wrong-shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-4px); }
  75% { transform: translateX(4px); }
}

@media (max-width: 430px) {
  .shell {
    padding: 10px;
  }

  .game {
    min-height: calc(100vh - 20px);
    border-radius: 24px;
  }

  .topbar,
  .scorebar {
    padding-inline: 16px;
  }

  .signal-panel {
    padding-inline: 16px;
  }

  .choice-grid {
    gap: 7px;
    padding-inline: 16px;
  }
}