:root {
  --bg: #11151b;
  --panel: #1a212b;
  --panel-2: #212a36;
  --border: #2c3744;
  --text: #e7ecf2;
  --text-dim: #8a96a6;
  --accent: #4fd1c5;
  --accent-soft: rgba(79, 209, 197, 0.14);
  --danger: #e0584a;
  --danger-soft: rgba(224, 88, 74, 0.14);
  --success: #5fd38d;
  --success-soft: rgba(95, 211, 141, 0.14);

  --peg-0: #e0483e; /* red */
  --peg-1: #36b37e; /* green */
  --peg-2: #4aa3ec; /* blue */
  --peg-3: #9b6dff; /* purple */
  --peg-4: #f3c012; /* yellow */
  --peg-5: #ef8d3c; /* orange */

  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

/*
 * Several rules below (.thinking, .btn, ...) set `display: flex` /
 * `inline-flex` unconditionally. Per the CSS cascade, an author-origin rule
 * always wins over the browser's built-in `[hidden] { display: none }`
 * user-agent rule, REGARDLESS of selector specificity or source order -
 * origin takes precedence over specificity. Without this rule, any element
 * that is both `hidden` and matched by one of those `display`-setting
 * classes stays visible. Concretely this caused the "Computing the optimal
 * guess..." panel to remain stuck on screen (frozen, since its countdown
 * timer is cleared once the request finishes) even after `thinking` flips
 * back to false - looking exactly like the app had become unresponsive.
 * `!important` here is intentional and restores the native, expected
 * behavior of the `hidden` attribute for every element, regardless of what
 * other classes are applied to it.
 */
[hidden] {
  display: none !important;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

.app {
  max-width: 1080px;
  margin: 0 auto;
  padding: 24px 20px 60px;
}

/* ---------- Header ---------- */

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 28px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 16px;
}

.brand-mark {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 4px;
  width: 40px;
  height: 40px;
  flex: none;
}

.brand-peg {
  border-radius: 50%;
  box-shadow: inset 0 -2px 3px rgba(0, 0, 0, 0.25), inset 0 1px 1px rgba(255, 255, 255, 0.25);
}

.brand-peg.p0 { background: var(--peg-0); }
.brand-peg.p1 { background: var(--peg-1); }
.brand-peg.p2 { background: var(--peg-2); }
.brand-peg.p4 { background: var(--peg-4); }

.brand h1 {
  margin: 0;
  font-size: 1.4rem;
  letter-spacing: 0.02em;
}

.subtitle {
  margin: 2px 0 0;
  color: var(--text-dim);
  font-size: 0.9rem;
}

/* ---------- Layout ---------- */

.layout {
  display: grid;
  grid-template-columns: 1fr 320px;
  gap: 20px;
  align-items: start;
}

@media (max-width: 820px) {
  .layout {
    grid-template-columns: 1fr;
  }
}

.panel-title {
  font-size: 1rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-dim);
  margin: 0 0 12px;
}

.board-panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 20px;
}

/* ---------- Board ---------- */

.board {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 10px 14px;
  border-radius: 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
}

.row.current {
  border-color: var(--accent);
  background: linear-gradient(180deg, var(--accent-soft), transparent 70%), var(--panel-2);
  box-shadow: 0 0 0 1px var(--accent-soft);
}

.row-index {
  font-variant-numeric: tabular-nums;
  color: var(--text-dim);
  font-size: 0.85rem;
  width: 64px;
  flex: none;
}

.row.current .row-index {
  color: var(--accent);
  font-weight: 600;
}

.row-label {
  display: block;
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-top: 2px;
  color: var(--text-dim);
}

.pegs {
  display: flex;
  gap: 8px;
}

.peg {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  font-weight: 700;
  color: #fff;
  box-shadow: inset 0 -3px 5px rgba(0, 0, 0, 0.25), inset 0 2px 2px rgba(255, 255, 255, 0.25);
}

.peg.peg-4 {
  color: #1a212b;
}

.peg.peg-3 {
  color: #fff;
}

.peg-0 { background: var(--peg-0); }
.peg-1 { background: var(--peg-1); }
.peg-2 { background: var(--peg-2); }
.peg-3 { background: var(--peg-3); }
.peg-4 { background: var(--peg-4); }
.peg-5 { background: var(--peg-5); }

.peg-mini {
  width: 22px;
  height: 22px;
  font-size: 0.65rem;
}

.feedback {
  margin-left: auto;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  grid-template-rows: repeat(2, 1fr);
  gap: 4px;
  width: 28px;
  height: 28px;
  flex: none;
}

.feedback-peg {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: #0d1117;
  border: 1px solid var(--border);
}

.feedback-peg.black {
  background: #0d1117;
  border-color: #444f5d;
}

.feedback-peg.white {
  background: #eef1f4;
  border-color: #c4ccd6;
}

.feedback-placeholder {
  margin-left: auto;
  width: 28px;
  height: 28px;
  flex: none;
}

/* ---------- Thinking indicator ---------- */

.thinking {
  margin-top: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
  padding: 12px 14px;
  border-radius: 10px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  font-size: 0.9rem;
  color: var(--text-dim);
}

.spinner {
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  flex: none;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

.thinking-time {
  font-variant-numeric: tabular-nums;
  color: var(--accent);
  font-weight: 600;
}

.btn-small {
  width: auto;
  padding: 4px 10px;
  font-size: 0.8rem;
  margin: 0 0 0 auto;
}

.exploratory-badge {
  display: inline-block;
  margin-top: 2px;
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 999px;
  padding: 1px 6px;
  white-space: nowrap;
}

/* ---------- Banner ---------- */

.banner {
  margin-top: 16px;
  padding: 14px 16px;
  border-radius: 10px;
  font-size: 0.95rem;
  line-height: 1.5;
}

.banner.success {
  background: var(--success-soft);
  border: 1px solid var(--success);
  color: var(--success);
}

.banner.info {
  background: var(--accent-soft);
  border: 1px solid var(--accent);
  color: var(--accent);
}

.banner.danger {
  background: var(--danger-soft);
  border: 1px solid var(--danger);
  color: var(--danger);
}

/* ---------- Side panel / cards ---------- */

.side-panel {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
}

.card h2 {
  margin: 0 0 10px;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--text-dim);
}

.hint {
  margin: 0 0 14px;
  font-size: 0.85rem;
  line-height: 1.5;
  color: var(--text-dim);
}

.hint strong {
  color: var(--text);
}

/* ---------- Stats ---------- */

.stats {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 0;
}

.stats > div {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}

.stats dt {
  color: var(--text-dim);
  font-size: 0.85rem;
}

.stats dd {
  margin: 0;
  font-size: 1.1rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

/* ---------- Segmented control ---------- */

.segmented {
  display: flex;
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
}

.segmented button {
  flex: 1;
  border: none;
  background: transparent;
  color: var(--text-dim);
  padding: 8px 0;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
}

.segmented button + button {
  border-left: 1px solid var(--border);
}

.segmented button.active {
  background: var(--accent-soft);
  color: var(--accent);
}

.segmented button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ---------- Peg counter / steppers ---------- */

.peg-counter {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 10px;
}

.peg-counter-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
}

.peg-dot {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  display: inline-block;
}

.peg-dot-black {
  background: #0d1117;
  border: 1px solid #444f5d;
}

.peg-dot-white {
  background: #eef1f4;
  border: 1px solid #c4ccd6;
}

.stepper {
  display: flex;
  align-items: center;
  gap: 10px;
}

.stepper span {
  min-width: 1.2em;
  text-align: center;
  font-size: 1.05rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.step-btn {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  font-size: 1.1rem;
  line-height: 1;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
}

.step-btn:hover:not(:disabled) {
  border-color: var(--accent);
}

.step-btn:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  padding: 10px 16px;
  border-radius: 10px;
  border: 1px solid var(--border);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, opacity 0.15s;
  margin-top: 4px;
}

.btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #0c1418;
}

.btn-primary:hover:not(:disabled) {
  opacity: 0.9;
}

.btn-primary:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.btn-ghost {
  background: transparent;
  color: var(--text);
  width: auto;
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
}

#new-game {
  flex: none;
}

/* ---------- Misc ---------- */

.error {
  margin: 10px 0 0;
  color: var(--danger);
  font-size: 0.85rem;
}

.legend {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.legend li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.footer {
  margin-top: 28px;
  text-align: center;
  color: var(--text-dim);
  font-size: 0.8rem;
}

.footer p {
  margin: 0;
}