/* ===================================
   CSS CUSTOM PROPERTIES
   =================================== */
:root {
  /* Colors - Monochrome Palette */
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-text-muted: #666666;
  --color-border: #e0e0e0;

  /* Board Colors */
  --color-square-light: #d9d9d9;
  --color-square-dark: #6b6b6b;
  --color-square-selected: #5a5a5a;
  --color-square-last-move: #7a7a7a;
  --color-square-valid: #9a9a9a;

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 0.75rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;

  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;

  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 6px;

  /* Transitions */
  --transition-base: 150ms ease;
}

/* ===================================
   BASE STYLES
   =================================== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-family);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
  min-height: 100vh;
}

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  outline: none;
}

/* ===================================
   APP CONTAINER
   =================================== */
.app-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  min-height: 100vh;
  padding: var(--spacing-md);
  gap: var(--spacing-lg);
}

/* ===================================
   GAME AREA
   =================================== */
.game-area {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  width: 100%;
  max-width: 520px;
}

/* ===================================
   PLAYER CARDS
   =================================== */
.player-card {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  padding: var(--spacing-md);
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
}

.player-card.active {
  border-left: 2px solid var(--color-text);
}

.player-avatar {
  width: clamp(36px, 8vw, 48px);
  height: clamp(36px, 8vw, 48px);
  border-radius: 50%;
  background-color: var(--color-text-muted);
  flex-shrink: 0;
}

.player-info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xs);
  flex: 1;
}

.player-name {
  font-size: clamp(0.875rem, 3vw, 1rem);
  font-weight: 600;
  color: var(--color-text);
}

.player-rating {
  font-size: clamp(0.75rem, 2vw, 0.875rem);
  color: var(--color-text-muted);
}

.turn-indicator {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: transparent;
  border: 1px solid var(--color-border);
  flex-shrink: 0;
}

.turn-indicator.active {
  background-color: var(--color-text);
  border: 1px solid var(--color-text);
}

/* ===================================
   BOARD CONTAINER
   =================================== */
.board-container {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
}

.board {
  width: 100%;
  height: 100%;
}

/* Custom monochrome board theme */
.cm-chessboard.monochrome .board .square.white {
  fill: var(--color-square-light);
}

.cm-chessboard.monochrome .board .square.black {
  fill: var(--color-square-dark);
}

.cm-chessboard.monochrome.border-type-frame .board .border {
  fill: var(--color-square-light);
  stroke: none;
}

.cm-chessboard.monochrome.border-type-frame .board .border-inner {
  fill: var(--color-square-dark);
  stroke: none;
}

.cm-chessboard.monochrome .coordinates .coordinate {
  fill: var(--color-text-muted);
  font-size: clamp(6px, 1.5vw, 7px);
  cursor: default;
}

.cm-chessboard.monochrome .coordinates .coordinate.black {
  fill: var(--color-text-muted);
}

.cm-chessboard.monochrome .coordinates .coordinate.white {
  fill: var(--color-text-muted);
}

/* Valid move highlights - flat overlays */
.cm-chessboard.monochrome .markers .marker.marker-square {
  fill: var(--color-square-valid);
  opacity: 0.5;
}

.cm-chessboard.monochrome .markers .marker.marker-dot {
  fill: var(--color-text-muted);
  opacity: 0.6;
}

.cm-chessboard.monochrome .markers .marker.marker-frame {
  stroke: var(--color-text-muted);
  stroke-width: 1.5px;
  opacity: 0.5;
}

.cm-chessboard.monochrome .markers .marker.marker-frame-primary {
  stroke: var(--color-text-muted);
  stroke-width: 1.5px;
  opacity: 0.5;
}

.cm-chessboard.monochrome .markers .marker.marker-circle {
  stroke: var(--color-text-muted);
  stroke-width: 2px;
  opacity: 0.5;
}

.cm-chessboard.monochrome .markers .marker.marker-circle-primary {
  stroke: var(--color-text-muted);
  stroke-width: 2px;
  opacity: 0.5;
}

/* Selected piece highlight */
.cm-chessboard.monochrome .square.highlight-selected {
  fill: var(--color-square-selected);
}

/* Last move highlight */
.cm-chessboard.monochrome .square.highlight-last {
  fill: var(--color-square-last-move);
}

/* ===================================
   MODEL LOADING
   =================================== */
.model-loading {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-bg);
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  z-index: 10;
  opacity: 1;
  visibility: visible;
  transition: opacity 0.3s, visibility 0.3s;
}

.model-loading.hidden {
  opacity: 0;
  visibility: hidden;
}

/* ===================================
   CONTROLS
   =================================== */
.controls {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
  flex-wrap: wrap;
  width: 100%;
  max-width: 520px;
}

.control-button {
  padding: var(--spacing-sm) var(--spacing-lg);
  background-color: transparent;
  color: var(--color-text);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: border-color var(--transition-base);
  min-height: 44px;
  min-width: 44px;
}

.control-button:hover {
  border-color: var(--color-text-muted);
}

.control-button:focus-visible {
  outline: 2px solid var(--color-text);
  outline-offset: 1px;
}

.control-button:active {
  border-color: var(--color-text);
}

/* ===================================
   OVERLAY
   =================================== */
.overlay {
  position: fixed;
  inset: 0;
  background-color: rgba(255, 255, 255, 0.95);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 1;
  visibility: visible;
  transition: opacity 0.3s, visibility 0.3s;
}

.overlay.hidden {
  opacity: 0;
  visibility: hidden;
}

.overlay-content {
  background-color: var(--color-bg);
  border: 1px solid var(--color-border);
  padding: var(--spacing-xl);
  border-radius: var(--radius-md);
  text-align: center;
  max-width: 90vw;
}

.overlay-content h2 {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: var(--spacing-lg);
}

.primary-button {
  padding: var(--spacing-sm) var(--spacing-xl);
  background-color: var(--color-text);
  color: var(--color-bg);
  border: 1px solid var(--color-text);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 500;
  transition: background-color var(--transition-base);
  min-height: 44px;
  min-width: 48px;
}

.primary-button:hover {
  background-color: #000000;
}

.primary-button:focus-visible {
  outline: 2px solid var(--color-text);
  outline-offset: 2px;
}

.primary-button:active {
  background-color: #333333;
}

/* ===================================
   ACCESSIBILITY
   =================================== */

/* Reduced Motion */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* High Contrast Mode */
@media (prefers-contrast: high) {
  :root {
    --color-border: #000000;
  }

  .control-button,
  .primary-button {
    border-width: 2px;
  }
}

/* Focus styles for keyboard navigation */
button:focus-visible {
  outline: 2px solid var(--color-text);
  outline-offset: 2px;
}