/* Ensure chess pieces keep a constant dark glyph color across all themes */
.chess-piece {
  color: var(--piece-black);
}
*,
*::before,
*::after {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
}

body {
  font-family: var(--font-family-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  display: flex;
  align-items: stretch;
  justify-content: center;
}

#app-root {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  min-height: 100vh;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.app-title {
  font-size: 1.4rem;
  font-weight: 600;
  margin: 0;
}

.theme-toggle {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--color-subtle-text);
}

.app-main {
  flex: 1;
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(260px, 0.9fr);
  gap: 16px;
  align-items: stretch;
}

/* Board container: always centered in its section */
.board-section {
  display: flex;
  align-items: center;
  justify-content: center;
}

#board-container {
  width: min(100%, 560px);
  aspect-ratio: 1 / 1;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  background-color: var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-soft);
}

/* Individual squares */
.chess-square {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: clamp(1.6rem, 3.2vw, 2.7rem);
  cursor: pointer;
  user-select: none;
  transition: background-color var(--transition-fast),
    box-shadow var(--transition-fast), transform var(--transition-fast);
}

.chess-square.light {
  background-color: var(--board-light);
}

.chess-square.dark {
  background-color: var(--board-dark);
}

.chess-square.highlight-selected {
  box-shadow: inset 0 0 0 2px var(--board-highlight);
}

.chess-square.highlight-legal::after {
  content: "";
  width: 26%;
  height: 26%;
  border-radius: 999px;
  background-color: var(--board-legal-move);
  box-shadow: 0 0 4px rgba(0, 0, 0, 0.28);
}

.chess-square.highlight-last-move {
  box-shadow: inset 0 0 0 2px var(--board-last-move);
}

/* Pieces as text-based icons for clarity and performance */
.chess-piece {
  z-index: 1;
  line-height: 1;
  text-shadow: 0 1px 2px rgba(0, 0, 0, 0.35);
}

/* Side panel styling */
.side-panel {
  background-color: var(--color-bg-elevated);
  border-radius: var(--radius-lg);
  padding: 14px 14px 12px;
  box-shadow: var(--shadow-soft);
  display: flex;
  flex-direction: column;
  gap: 12px;
  border: 1px solid var(--color-border);
}

.side-panel section h2 {
  margin: 0 0 6px;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-subtle-text);
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.controls-section,
.status-section,
.history-section {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.control-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: 4px;
  font-size: 0.9rem;
}

.btn-group {
  display: inline-flex;
  gap: 4px;
  flex-wrap: wrap;
}

.btn {
  border: none;
  border-radius: 999px;
  padding: 6px 10px;
  font-size: 0.82rem;
  cursor: pointer;
  background-color: var(--btn-bg);
  color: var(--btn-text);
  transition: background-color var(--transition-fast),
    color var(--transition-fast), transform var(--transition-fast),
    box-shadow var(--transition-fast);
}

.btn-sm {
  padding: 4px 9px;
  font-size: 0.78rem;
}

.btn-primary {
  background-color: var(--btn-bg-primary);
  color: var(--btn-text-primary);
  font-weight: 500;
}

.btn:hover {
  background-color: var(--btn-bg-hover);
  transform: translateY(-1px);
  box-shadow: 0 4px 10px rgba(15, 23, 42, 0.18);
}

.btn-primary:hover {
  background-color: var(--btn-bg-primary-hover);
}

.btn.active {
  background-color: var(--color-accent);
  color: var(--btn-text-primary);
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.35);
}

/* Selects */
select {
  padding: 4px 8px;
  border-radius: 8px;
  border: 1px solid var(--color-border);
  font-size: 0.82rem;
  background-color: var(--color-bg-elevated);
  color: var(--color-text);
}

/* Status & history */
.status-text {
  font-size: 0.9rem;
  color: var(--color-text);
}

.status-text.busy {
  font-style: italic;
  opacity: 0.8;
}

.status-sub {
  font-size: 0.78rem;
  color: var(--color-subtle-text);
}

.move-history-list {
  list-style: decimal;
  margin: 2px 0 0;
  padding-left: 20px;
  font-size: 0.78rem;
  max-height: 180px;
  overflow-y: auto;
}

/* Scrollbar minimal styling */
.move-history-list::-webkit-scrollbar {
  width: 4px;
}
.move-history-list::-webkit-scrollbar-track {
  background: transparent;
}
.move-history-list::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 999px;
}

/* Responsive layout */

@media (max-width: 900px) {
  .app-main {
    grid-template-columns: 1fr;
  }

  .side-panel {
    order: 2;
  }

  .board-section {
    order: 1;
  }

  #board-container {
    width: min(100%, 86vw);
  }
}

@media (max-width: 540px) {
  #app-root {
    padding: 10px;
    gap: 10px;
  }

  .app-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 4px;
  }

  .app-title {
    font-size: 1.25rem;
  }

  .side-panel {
    padding: 10px;
  }

  #board-container {
    width: min(100%, 94vw);
  }
}

/* Game End Modal */
.game-end-modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-fast), visibility var(--transition-fast);
  pointer-events: none;
}

.game-end-modal.game-end-modal-visible {
  opacity: 1;
  visibility: visible;
  pointer-events: all;
}

.game-end-modal-backdrop {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
}

.game-end-modal-content {
  position: relative;
  background-color: var(--color-bg-elevated);
  border-radius: var(--radius-lg);
  padding: 32px;
  max-width: 420px;
  width: 90%;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.3);
  border: 1px solid var(--color-border);
  text-align: center;
  transform: scale(0.9);
  transition: transform var(--transition-fast);
  z-index: 1;
}

.game-end-modal.game-end-modal-visible .game-end-modal-content {
  transform: scale(1);
}

.game-end-icon {
  font-size: 4rem;
  line-height: 1;
  margin-bottom: 16px;
  animation: modalIconPop 0.4s ease-out;
}

@keyframes modalIconPop {
  0% {
    transform: scale(0);
    opacity: 0;
  }
  50% {
    transform: scale(1.2);
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}

.game-end-title {
  font-size: 2rem;
  font-weight: 700;
  margin: 0 0 12px;
  color: var(--color-text);
}

.game-end-message {
  font-size: 1rem;
  color: var(--color-subtle-text);
  margin: 0 0 24px;
  line-height: 1.5;
}

.game-end-actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

.game-end-actions .btn {
  min-width: 120px;
  padding: 10px 20px;
  font-size: 0.9rem;
}

/* Modal variants */
.game-end-modal-victory .game-end-title {
  color: #10b981;
}

.game-end-modal-defeat .game-end-title {
  color: #ef4444;
}

.game-end-modal-draw .game-end-title {
  color: var(--color-accent);
}

/* Responsive modal */
@media (max-width: 540px) {
  .game-end-modal-content {
    padding: 24px;
    max-width: 90%;
  }

  .game-end-icon {
    font-size: 3rem;
    margin-bottom: 12px;
  }

  .game-end-title {
    font-size: 1.5rem;
  }

  .game-end-message {
    font-size: 0.9rem;
    margin-bottom: 20px;
  }

  .game-end-actions {
    flex-direction: column;
  }

  .game-end-actions .btn {
    width: 100%;
    min-width: auto;
  }
}