/* ---------------------------------------------------------------
   Opening Trainer
   Mobile-first; matches the dark chess theme shared by the other
   PairFX sub-apps (opening-tree, 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;
}

button {
  font-family: inherit;
}

/* ---------- error banner / loading ---------- */

.error-banner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--spacing-md);
  background: var(--color-danger);
  color: #fff;
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius);
  margin-bottom: var(--spacing-md);
}

.error-banner button {
  background: none;
  border: none;
  color: #fff;
  cursor: pointer;
  font-size: 1rem;
}

.notice-banner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: var(--spacing-md);
  background: var(--color-secondary);
  border: 1px solid var(--color-info);
  color: var(--color-light);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius);
  margin-bottom: var(--spacing-md);
}

.notice-banner button {
  background: none;
  border: none;
  color: var(--color-light);
  cursor: pointer;
  font-size: 1rem;
}

.loading-store {
  text-align: center;
  color: #b8b8b8;
  padding: var(--spacing-xl);
}

/* ---------- repertoire list ---------- */

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

.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;
}

.train-all {
  display: block;
  width: 100%;
  margin-bottom: var(--spacing-md);
  padding: var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-info);
  background: var(--color-secondary);
  color: var(--color-info);
  cursor: pointer;
  font-size: 0.95rem;
}

.train-all:hover {
  background: var(--color-accent);
}

.repertoires {
  list-style: none;
  margin: 0 0 var(--spacing-lg);
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.repertoire-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--spacing-sm);
  background: var(--color-secondary);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius);
}

.repertoire-name {
  font-weight: bold;
  flex: 1 1 160px;
  cursor: pointer;
}

.repertoire-name:hover {
  text-decoration: underline;
}

.repertoire-count {
  color: #b8b8b8;
  font-size: 0.85rem;
  flex: 0 0 auto;
}

.repertoire-mastery {
  color: var(--color-success);
  font-size: 0.8rem;
  flex: 0 0 auto;
}

.repertoire-row button {
  padding: var(--spacing-xs) 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: 0.85rem;
}

.repertoire-row button:hover {
  background: var(--color-accent);
}

.repertoire-row button.delete {
  border-color: var(--color-danger);
  color: var(--color-danger);
}

.empty-list {
  color: #b8b8b8;
  font-style: italic;
  margin-bottom: var(--spacing-lg);
}

.create-form,
.upload-form {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--spacing-sm);
  background: var(--color-secondary);
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
  margin-bottom: var(--spacing-md);
}

.create-form input,
.upload-form input,
.upload-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: 0.95rem;
}

.upload-form label {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: 0.9rem;
}

.create-form button,
.upload-form button,
.settings-actions button {
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--border-radius);
  border: none;
  background: var(--color-info);
  color: #fff;
  font-size: 0.95rem;
  cursor: pointer;
}

.create-form button:hover,
.upload-form button:hover,
.settings-actions button:hover {
  filter: brightness(1.1);
}

/* ---------- browse ---------- */

.browse-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-sm);
}

.browse-header h2 {
  flex: 1;
  margin: 0;
  font-size: 1.15rem;
}

.back-to-list,
.train-repertoire {
  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;
}

.back-to-list:hover,
.train-repertoire:hover {
  background: var(--color-accent);
}

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

.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 (shared: browse + training) ---------- */

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

.board-toolbar {
  display: flex;
  justify-content: space-between;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xs);
}

.drill-branch,
.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;
}

.drill-branch:hover,
.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);
}

.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);
}

/* A "hint" square (strict wrong-move handling: the correct move, revealed) gets a glowing ring
   distinct from the ordinary move-target dot, so it reads as "the answer" rather than just
   "a legal destination." */
.board .square.hint {
  box-shadow: inset 0 0 0 3px var(--color-warning);
}

/* A square currently being dragged over (native HTML5 drag-and-drop) — distinct from
   .move-target so hovering while dragging reads as "this is where it'll land" even before the
   drop actually resolves against the tracked/legal moves. */
.board .square.drag-over {
  background: var(--color-info);
  opacity: 0.6;
}

.board .square .piece[draggable="true"] {
  cursor: grab;
}

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

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

.mastery-summary {
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-success);
  margin-top: var(--spacing-xs);
}

.show-comments-toggle {
  display: flex;
  align-items: center;
  gap: var(--spacing-xs);
  font-size: 0.85rem;
  color: #b8b8b8;
  margin-bottom: var(--spacing-md);
  cursor: pointer;
  width: fit-content;
}

.position-comment {
  font-size: 0.85rem;
  color: var(--color-light);
  background: var(--color-secondary);
  border-radius: var(--border-radius);
  padding: var(--spacing-sm);
  margin-top: var(--spacing-sm);
  text-align: left;
  max-height: 8rem;
  overflow-y: auto;
}

/* ---------- 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;
}

.badge {
  font-size: 0.75rem;
  white-space: nowrap;
}

.badge-opponent {
  color: #b8b8b8;
}

.badge-new {
  color: var(--color-info);
}

.badge-due {
  color: var(--color-warning);
}

.badge-learning {
  color: var(--color-light);
}

.badge-known {
  color: var(--color-success);
}

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

/* ---------- settings screen ---------- */

.settings-screen {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  background: var(--color-secondary);
  padding: var(--spacing-lg);
  border-radius: var(--border-radius);
  max-width: 480px;
}

.settings-screen label {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  font-size: 0.9rem;
}

.settings-screen 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: 0.95rem;
}

.settings-actions {
  display: flex;
  gap: var(--spacing-sm);
}

.cancel-settings {
  background: var(--color-primary);
  border: 1px solid var(--color-accent);
}

/* ---------- training ---------- */

.training-header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-md);
  font-size: 0.9rem;
}

.training-repertoire {
  font-weight: bold;
  flex: 1;
}

.training-progress {
  color: #b8b8b8;
}

.end-session {
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-danger);
  background: var(--color-primary);
  color: var(--color-danger);
  cursor: pointer;
  font-size: 0.85rem;
}

.training-new-variation {
  text-align: center;
  margin-bottom: var(--spacing-sm);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-info);
  background: var(--color-secondary);
  color: var(--color-info);
  font-size: 0.85rem;
  font-weight: bold;
}

.training-feedback {
  text-align: center;
  margin-bottom: var(--spacing-sm);
  /* Reserves room for the longer wrong-move message up front, so switching between the short
     prompt and the wrong-move feedback never reflows (and so shifts) the board sitting below
     it, on any viewport width. */
  min-height: 2.8em;
}

.training-feedback.prompt {
  color: #b8b8b8;
}

.training-feedback.wrong {
  color: var(--color-warning);
  font-weight: bold;
}

.training .board-toolbar {
  justify-content: flex-end;
}

.continue-training {
  display: block;
  margin: 0 auto var(--spacing-md);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--border-radius);
  border: none;
  background: var(--color-info);
  color: #fff;
  cursor: pointer;
}

/* ---------- summary ---------- */

.summary-screen {
  text-align: center;
  background: var(--color-secondary);
  padding: var(--spacing-xl);
  border-radius: var(--border-radius);
  max-width: 420px;
  margin: var(--spacing-xl) auto;
}

.summary-screen button {
  margin-top: var(--spacing-md);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--border-radius);
  border: none;
  background: var(--color-info);
  color: #fff;
  cursor: pointer;
}

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

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