/* ---------------------------------------------------------------
   Opening Tree — Opponent Prep
   Mobile-first; matches the dark chess theme shared by the other
   PairFX sub-apps (opening-selector, chess-classroom).
--------------------------------------------------------------- */

:root {
  --color-primary: #1a1a1a;
  --color-secondary: #2d2d2d;
  --color-accent: #4a4a4a;
  --color-light: #e8e8e8;
  --color-white: #ffffff;
  --color-success: #28a745;
  --color-warning: #ffc107;
  --color-danger: #dc3545;
  --color-info: #17a2b8;

  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;

  --border-radius: 8px;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-secondary) 100%);
  color: var(--color-light);
  min-height: 100vh;
  line-height: 1.5;
}

.page {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

header {
  background: #000;
  padding: var(--spacing-lg);
  text-align: center;
  border-bottom: 3px solid var(--color-accent);
}

header h1 {
  margin: 0 0 var(--spacing-xs);
  font-size: 1.6rem;
}

header .subtitle {
  margin: 0 0 var(--spacing-sm);
  color: #b8b8b8;
  font-size: 0.95rem;
}

.back-link {
  color: var(--color-info);
  text-decoration: none;
  font-size: 0.9rem;
}

.back-link:hover {
  text-decoration: underline;
}

#app {
  flex: 1;
  padding: var(--spacing-md);
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
}

/* ---------- lookup form ---------- */

.lookup-form {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  background: var(--color-secondary);
  padding: var(--spacing-lg);
  border-radius: var(--border-radius);
  align-items: flex-end;
}

.lookup-form label {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  font-size: 0.9rem;
  flex: 1 1 160px;
}

.lookup-form input,
.lookup-form select {
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-accent);
  background: var(--color-primary);
  color: var(--color-light);
  font-size: 1rem;
}

.lookup-form button {
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--border-radius);
  border: none;
  background: var(--color-info);
  color: #fff;
  font-size: 1rem;
  cursor: pointer;
  flex: 0 0 auto;
}

.lookup-form button:hover {
  filter: brightness(1.1);
}

.lookup-form button:disabled {
  opacity: 0.6;
  cursor: wait;
}

/* ---------- status ---------- */

.status {
  margin-top: var(--spacing-md);
}

.status.error {
  color: var(--color-danger);
  font-weight: bold;
}

.status.loading {
  color: var(--color-light);
}

.status.loading p {
  margin: 0 0 var(--spacing-xs);
}

.progress-bar {
  position: relative;
  height: 10px;
  border-radius: 5px;
  background: var(--color-secondary);
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--color-info);
  transition: width 0.2s ease;
}

.progress-bar.indeterminate .progress-bar-fill {
  position: absolute;
  top: 0;
  width: 35%;
  animation: progress-indeterminate 1.2s ease-in-out infinite;
}

@keyframes progress-indeterminate {
  0% {
    left: -35%;
  }
  100% {
    left: 100%;
  }
}

.progress-bar-label {
  display: block;
  font-size: 0.75rem;
  color: #b8b8b8;
  margin-top: var(--spacing-xs);
}

/* ---------- results ---------- */

.results {
  margin-top: var(--spacing-lg);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.summary {
  font-size: 0.95rem;
  color: #b8b8b8;
}

.color-tabs {
  display: flex;
  gap: var(--spacing-sm);
}

.color-tabs button {
  flex: 1;
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-accent);
  background: var(--color-primary);
  color: var(--color-light);
  cursor: pointer;
  font-size: 1rem;
}

.color-tabs button.active {
  background: var(--color-info);
  border-color: var(--color-info);
  color: #fff;
}

.filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-md);
  background: var(--color-secondary);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius);
  align-items: center;
  font-size: 0.9rem;
}

.speed-filters {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-sm);
}

.speed-filters label {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  text-transform: capitalize;
}

.filters select {
  padding: var(--spacing-xs);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-accent);
  background: var(--color-primary);
  color: var(--color-light);
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: var(--spacing-xs);
  font-size: 0.9rem;
}

.breadcrumb button {
  background: none;
  border: none;
  color: var(--color-info);
  cursor: pointer;
  padding: 0;
  font-size: 0.9rem;
}

.breadcrumb button:hover {
  text-decoration: underline;
}

.breadcrumb .sep {
  color: #888;
}

.explorer {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

@media (min-width: 700px) {
  .explorer {
    flex-direction: row;
    align-items: flex-start;
  }

  .board-wrap {
    flex: 0 0 auto;
  }

  .move-list {
    flex: 1;
  }
}

/* ---------- board ---------- */

.board-wrap {
  width: min(90vw, 420px);
  margin: 0 auto;
}

.board-toolbar {
  display: flex;
  justify-content: flex-end;
  margin-bottom: var(--spacing-xs);
}

.flip-board {
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-accent);
  background: var(--color-secondary);
  color: var(--color-light);
  cursor: pointer;
  font-size: 0.85rem;
}

.flip-board:hover {
  background: var(--color-accent);
}

.board {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  width: 100%;
  aspect-ratio: 1;
  border: 2px solid var(--color-accent);
  border-radius: 4px;
  overflow: hidden;
}

.board .square {
  display: flex;
  align-items: center;
  justify-content: center;
  user-select: none;
  cursor: pointer;
  position: relative;
}

.board .square.light {
  background: #e8dfc8;
}

.board .square.dark {
  background: #7a6a52;
}

.board .square.selected {
  box-shadow: inset 0 0 0 3px var(--color-accent);
}

/* A move-target square gets a dot (empty square) or a ring (capture) rather than a fill, so the
   piece already on it — if any — stays fully visible. */
.board .square.move-target::after {
  content: "";
  position: absolute;
  border-radius: 50%;
}

.board .square.move-target:not(:has(.piece))::after {
  width: 30%;
  height: 30%;
  background: rgba(0, 0, 0, 0.35);
}

.board .square.move-target:has(.piece)::after {
  inset: 6%;
  box-shadow: inset 0 0 0 3px rgba(0, 0, 0, 0.35);
}

.board .square .piece {
  width: 88%;
  height: 88%;
}

.node-summary {
  text-align: center;
  font-size: 0.9rem;
  color: #b8b8b8;
  margin-top: var(--spacing-sm);
}

/* ---------- games panel ---------- */

.games-panel {
  margin-top: var(--spacing-sm);
}

.games-toggle {
  display: block;
  width: 100%;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-accent);
  background: var(--color-secondary);
  color: var(--color-light);
  cursor: pointer;
  font-size: 0.85rem;
}

.games-toggle:hover {
  background: var(--color-accent);
}

.games-list {
  list-style: none;
  margin: var(--spacing-sm) 0 0;
  padding: 0;
  max-height: 320px;
  overflow-y: auto;
  border-radius: var(--border-radius);
  background: var(--color-secondary);
}

.game-row {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-xs) var(--spacing-sm);
  font-size: 0.8rem;
}

.game-row + .game-row {
  border-top: 1px solid var(--color-primary);
}

.game-outcome {
  flex: 0 0 34px;
  font-weight: bold;
  font-size: 0.7rem;
  text-align: center;
  border-radius: 3px;
  padding: 1px 0;
}

.game-outcome.win {
  background: var(--color-success);
  color: #fff;
}

.game-outcome.draw {
  background: var(--color-warning);
  color: #1a1a1a;
}

.game-outcome.loss {
  background: var(--color-danger);
  color: #fff;
}

.game-date {
  flex: 0 0 auto;
  color: #b8b8b8;
  white-space: nowrap;
}

.game-players {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.game-players strong {
  color: var(--color-light);
}

.game-speed {
  flex: 0 0 auto;
  color: #b8b8b8;
  text-transform: capitalize;
}

.game-link {
  flex: 0 0 auto;
  color: var(--color-info);
  text-decoration: none;
  white-space: nowrap;
}

.game-link:hover {
  text-decoration: underline;
}

.games-more-note {
  font-size: 0.75rem;
  color: #888;
  text-align: center;
  margin: var(--spacing-xs) 0 0;
}

/* ---------- move list ---------- */

.move-list table {
  width: 100%;
  border-collapse: collapse;
}

.move-list th,
.move-list td {
  padding: var(--spacing-sm);
  text-align: left;
  font-size: 0.9rem;
}

.move-list tbody tr {
  cursor: pointer;
  background: var(--color-secondary);
}

.move-list tbody tr:hover {
  background: var(--color-accent);
}

.move-list tbody tr + tr {
  border-top: 4px solid var(--color-primary);
}

.move-list .san {
  font-weight: bold;
  white-space: nowrap;
}

.move-list .count {
  white-space: nowrap;
  color: #b8b8b8;
}

.result-bar {
  display: flex;
  height: 14px;
  width: 100%;
  min-width: 80px;
  border-radius: 3px;
  overflow: hidden;
  background: var(--color-primary);
}

.result-bar .win {
  background: var(--color-success);
}

.result-bar .draw {
  background: var(--color-warning);
}

.result-bar .loss {
  background: var(--color-danger);
}

.empty-node {
  color: #b8b8b8;
  font-style: italic;
  padding: var(--spacing-md);
  text-align: center;
}

.legend {
  display: flex;
  gap: var(--spacing-md);
  font-size: 0.8rem;
  color: #b8b8b8;
  flex-wrap: wrap;
}

.legend span::before {
  content: "";
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 2px;
  margin-right: 4px;
  vertical-align: middle;
}

.legend .win::before {
  background: var(--color-success);
}

.legend .draw::before {
  background: var(--color-warning);
}

.legend .loss::before {
  background: var(--color-danger);
}

footer.credit {
  text-align: center;
  padding: var(--spacing-md);
  font-size: 0.8rem;
  color: #777;
}

footer.credit a {
  color: var(--color-info);
}