*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --black:     #0A0A0A;
  --bone:      #F0EBE3;
  --concrete:  #2A2826;
  --dim:       #635E59;

  --teal:      #00F0B5;
  --blue:      #0038FF;
  --red:       #FF0A0A;
  --yellow:    #FFD900;
  --pink:      #FF0090;
}

html { background: var(--black); }

body {
  background: var(--black);
  color: var(--bone);
  font-family: 'IBM Plex Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-weight: 300;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 4rem 2rem 5rem;
}

a { color: var(--bone); text-decoration: none; }
a:hover { color: var(--teal); }

#app {
  width: 100%;
  max-width: 640px;
}

h1, h2, h3 {
  font-family: 'IBM Plex Sans', sans-serif;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--bone);
}

h1 {
  text-align: center;
  font-size: 2.8rem;
  letter-spacing: 0.25em;
  margin-bottom: 2rem;
}

h2 {
  font-size: 0.85rem;
  color: var(--dim);
  letter-spacing: 0.12em;
  margin-bottom: 1.4rem;
}

.panel {
  background: var(--concrete);
  padding: 2rem;
}

.hidden { display: none !important; }

/* Settings */
.setting {
  margin-bottom: 1.4rem;
}

.setting label {
  display: block;
  font-size: 0.78rem;
  font-weight: 300;
  color: var(--dim);
  margin-bottom: 0.5rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

select, input[type="number"] {
  background: var(--black);
  border: 1px solid rgba(240, 235, 227, 0.1);
  border-radius: 0;
  color: var(--bone);
  padding: 0.55rem 0.75rem;
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.88rem;
  font-weight: 300;
  outline: none;
  transition: border-color 0.15s;
}

select:focus, input[type="number"]:focus {
  border-color: var(--teal);
}

select { width: 100%; }

#pile-inputs {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
  margin-bottom: 0.8rem;
}

.pile-input {
  width: 64px;
  text-align: center;
}

.pile-buttons {
  display: flex;
  gap: 0.5rem;
}

/* Buttons */
button {
  cursor: pointer;
  font-family: 'IBM Plex Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-weight: 300;
  border-radius: 0;
  transition: color 0.15s, background 0.15s, border-color 0.15s;
}

.btn-primary {
  background: var(--blue);
  color: var(--bone);
  border: none;
  padding: 0.65rem 1.5rem;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  width: 100%;
  margin-top: 1rem;
}
.btn-primary:hover { background: var(--teal); color: var(--black); }
.btn-primary:disabled { background: var(--dim); color: var(--concrete); cursor: not-allowed; }

.btn-danger {
  background: transparent;
  color: var(--red);
  border: 1px solid var(--red);
  padding: 0.55rem 1.2rem;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  width: 100%;
  margin-top: 0.75rem;
}
.btn-danger:hover { background: var(--red); color: var(--bone); }

.btn-sm {
  background: transparent;
  color: var(--dim);
  border: 1px solid rgba(240, 235, 227, 0.1);
  padding: 0.35rem 0.75rem;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}
.btn-sm:hover { color: var(--teal); border-color: var(--teal); }

/* Status bar */
#status-bar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.4rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid rgba(240, 235, 227, 0.07);
}

#turn-label {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 300;
  font-size: 0.88rem;
  color: var(--teal);
  letter-spacing: 0.04em;
}

/* AI's turn uses pink */
#turn-label.ai-turn {
  color: var(--pink);
}

#variant-label {
  font-size: 0.72rem;
  color: var(--dim);
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

/* Piles */
#piles-container {
  display: flex;
  flex-direction: column;
  gap: 1px;
  margin-bottom: 1.6rem;
}

.pile-row {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.85rem 1rem;
  background: var(--black);
  border: 1px solid transparent;
  cursor: pointer;
  transition: border-color 0.15s;
}

.pile-row:hover:not(.empty):not(.disabled) {
  border-color: var(--teal);
}

.pile-row.selected {
  border-color: var(--teal);
}

.pile-row.empty {
  opacity: 0.2;
  cursor: default;
}

.pile-row.disabled {
  cursor: default;
}

.pile-label {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.72rem;
  color: var(--dim);
  min-width: 52px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

.stones {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  flex: 1;
}

.stone {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--bone);
  opacity: 0.7;
  transition: opacity 0.25s, transform 0.25s;
}

.stone.removing {
  opacity: 0;
  transform: scale(0.3);
}

.stone.selected-stone {
  background: var(--teal);
  opacity: 1;
}

.pile-count {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 0.78rem;
  color: var(--dim);
  min-width: 28px;
  text-align: right;
}

/* Controls */
#controls {
  background: var(--black);
  padding: 1rem;
  margin-bottom: 1rem;
  border: 1px solid rgba(240, 235, 227, 0.07);
}

.control-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
  font-size: 0.88rem;
}

.control-row label {
  font-family: 'IBM Plex Mono', monospace;
  color: var(--dim);
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  min-width: 36px;
}

#take-count { width: 70px; text-align: center; }

#selected-pile-label {
  font-family: 'IBM Plex Mono', monospace;
  font-weight: 300;
  color: var(--teal);
}

/* Result */
#result-banner {
  background: var(--black);
  border: 1px solid var(--yellow);
  padding: 1.8rem;
  text-align: center;
  margin-bottom: 1rem;
}

#result-text {
  font-family: 'IBM Plex Mono', monospace;
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--yellow);
  margin-bottom: 0.6rem;
}

#play-again { margin-top: 0; }

/* Back button — Signal Red for return navigation */
#back-btn {
  background: transparent;
  color: var(--red);
  border: 1px solid var(--red);
}
#back-btn:hover {
  background: var(--red);
  color: var(--bone);
}

/* AI thinking indicator */
.ai-thinking #turn-label::after {
  content: ' …';
  animation: blink 0.8s step-end infinite;
}

@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0; }
}

/* Site mark — parallel morphism logo, bottom center */
.site-mark {
  position: fixed;
  bottom: 1.5rem;
  left: 50%;
  transform: translateX(-50%);
  color: var(--bone);
  opacity: 0.45;
  transition: color 0.15s, opacity 0.15s;
  line-height: 0;
  display: block;
}
.site-mark:hover {
  color: var(--red);
  opacity: 1;
}

/* Responsive: generous spacing on larger screens */
@media (min-width: 768px) {
  body { padding: 4rem 6rem 5rem; }
}