/* ==========================================================================
   Tic-Tac-Toe Styles
   ========================================================================== */

/* ---- CSS Custom Properties (Design Tokens) ---- */
:root {
  /* Color palette */
  --color-bg: #0f1117;
  --color-surface: #1a1d27;
  --color-surface-raised: #232735;
  --color-border: #2e3344;
  --color-text: #e6e9f0;
  --color-text-muted: #9aa3b5;
  --color-x: #4f8cff;
  --color-o: #ff6b6b;
  --color-accent: #7c6cff;
  --color-accent-soft: rgba(124, 108, 255, 0.16);
  --color-win: #3ddc97;
  --color-overlay: rgba(10, 12, 18, 0.72);

  /* Typography */
  --font-ui: "Segoe UI", system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;

  /* Layout */
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --shadow-card: 0 18px 40px rgba(0, 0, 0, 0.35);

  /* Motion */
  --transition-fast: 0.18s ease;
  --transition-base: 0.3s ease;

  /* Fixed board geometry (derived from a CSS variable for cell sizing) */
  --board-size: 340px;
  --cell-gap: 10px;
}

/* Light theme overrides */
[data-theme="light"] {
  --color-bg: #f3f4f8;
  --color-surface: #ffffff;
  --color-surface-raised: #eceef4;
  --color-border: #d9dce6;
  --color-text: #1c2030;
  --color-text-muted: #5d6575;
  --color-x: #2f6fe0;
  --color-o: #e04444;
  --color-accent: #6a5cff;
  --color-accent-soft: rgba(106, 92, 255, 0.12);
  --color-win: #17a05f;
  --color-overlay: rgba(40, 44, 58, 0.55);
  --shadow-card: 0 18px 40px rgba(30, 34, 50, 0.18);
}

/* ---- Base Reset ---- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  color-scheme: dark;
}

[data-theme="light"] {
  color-scheme: light;
}

body {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px 16px;
  font-family: var(--font-ui);
  color: var(--color-text);
  background: var(--color-bg);
  transition: background var(--transition-base), color var(--transition-base);
}

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

.hidden {
  display: none !important;
}

/* Board becomes non-interactive while the AI is thinking */
.board.disabled {
  pointer-events: none;
  opacity: 0.75;
  transition: opacity var(--transition-fast);
}

/* ---- App Layout ---- */
.app {
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  gap: 20px;
}

/* ---- Header ---- */
.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.app-title {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: linear-gradient(120deg, var(--color-x), var(--color-accent), var(--color-o));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Theme toggle button + icons */
.theme-toggle {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  transition: background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

.theme-toggle:hover {
  border-color: var(--color-accent);
  transform: rotate(8deg) scale(1.05);
}

.icon {
  width: 22px;
  height: 22px;
  transition: opacity var(--transition-base), transform var(--transition-base);
}

/* Only show the sun (light mode target) in dark theme and vice-versa */
[data-theme="dark"] .icon-sun,
[data-theme="light"] .icon-moon {
  opacity: 1;
  transform: scale(1);
}

[data-theme="dark"] .icon-moon,
[data-theme="light"] .icon-sun {
  opacity: 0;
  transform: scale(0.5) rotate(-90deg);
  position: absolute;
  pointer-events: none;
}

/* ---- Controls (mode / difficulty) ---- */
.controls {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.mode-switch,
.difficulty-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 8px;
  padding: 6px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.mode-btn {
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-text-muted);
  transition: background var(--transition-fast), color var(--transition-fast);
}

.mode-btn:hover {
  color: var(--color-text);
}

.mode-btn.is-active {
  background: var(--color-accent-soft);
  color: var(--color-accent);
}

/* ---- Status text ---- */
.status {
  text-align: center;
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text-muted);
  min-height: 1.5em;
  transition: color var(--transition-fast);
}

.status.turn-x {
  color: var(--color-x);
}

.status.turn-o {
  color: var(--color-o);
}

/* ---- Scoreboard ---- */
.scoreboard {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.score-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 12px 8px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.score-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
}

.score-value {
  font-size: 1.4rem;
  font-weight: 800;
}

#score-x {
  color: var(--color-x);
}

#score-o {
  color: var(--color-o);
}

#score-ties {
  color: var(--color-text-muted);
}

/* ---- Board ---- */
.board-wrap {
  display: flex;
  justify-content: center;
}

.board {
  width: var(--board-size);
  height: var(--board-size);
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  gap: var(--cell-gap);
  padding: var(--cell-gap);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
}

/* Individual cells */
.cell {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-md);
  background: var(--color-surface-raised);
  border: 1px solid transparent;
  transition: background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast);
}

/* Hover indicator for empty cells when it is a human's turn */
.cell:not(.taken):not(.win):hover {
  background: var(--color-accent-soft);
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.cell:not(.taken):not(.win):hover::after {
  content: attr(data-preview);
  font-size: 3.2rem;
  font-weight: 800;
  opacity: 0.35;
  pointer-events: none;
}

/* Winning cells */
.cell.win {
  background: var(--color-win);
  border-color: transparent;
  animation: pulse 0.6s ease-in-out infinite alternate;
}

@keyframes pulse {
  from {
    box-shadow: 0 0 0 0 rgba(61, 220, 151, 0.4);
  }
  to {
    box-shadow: 0 0 0 10px rgba(61, 220, 151, 0);
  }
}

/* ---- Markings (X / O) ---- */
.mark {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 3.2rem;
  font-weight: 800;
  line-height: 1;
  animation: pop-in 0.28s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

.mark-x {
  color: var(--color-x);
}

.mark-o {
  color: var(--color-o);
}

/* Emphasize X / O strokes with a subtle shadow for depth */
.mark-x {
  text-shadow: 0 4px 14px rgba(79, 140, 255, 0.45);
}

.mark-o {
  text-shadow: 0 4px 14px rgba(255, 107, 107, 0.45);
}

/* Pop-in animation used for newly placed marks */
@keyframes pop-in {
  0% {
    opacity: 0;
    transform: scale(0.3) rotate(-20deg);
  }
  70% {
    transform: scale(1.15) rotate(6deg);
  }
  100% {
    opacity: 1;
    transform: scale(1) rotate(0deg);
  }
}

/* ---- Action buttons ---- */
.actions {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 10px;
}

.btn {
  padding: 12px 10px;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 700;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  transition: background var(--transition-fast), border-color var(--transition-fast), transform var(--transition-fast), opacity var(--transition-fast);
}

.btn:hover:not(:disabled) {
  border-color: var(--color-accent);
  transform: translateY(-2px);
}

.btn:active:not(:disabled) {
  transform: translateY(0);
}

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

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

.btn-primary:hover:not(:disabled) {
  filter: brightness(1.1);
}

/* ---- Overlay (win / draw message) ---- */
.overlay {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: grid;
  place-items: center;
  background: var(--color-overlay);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  animation: fade-in 0.25s ease both;
}

.overlay-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 14px;
  padding: 36px 44px;
  text-align: center;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  animation: slide-up 0.3s cubic-bezier(0.34, 1.56, 0.64, 1) both;
}

.overlay-title {
  font-size: 2rem;
  font-weight: 800;
}

.overlay-title.x {
  color: var(--color-x);
}

.overlay-title.o {
  color: var(--color-o);
}

.overlay-title.draw {
  color: var(--color-text-muted);
}

.overlay-subtitle {
  color: var(--color-text-muted);
}

@keyframes fade-in {
  from {
    opacity: 0;
  }
  to {
    opacity: 1;
  }
}

@keyframes slide-up {
  from {
    opacity: 0;
    transform: translateY(24px) scale(0.96);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

/* ---- Responsive adjustments ---- */
@media (max-width: 420px) {
  :root {
    --board-size: 300px;
  }

  .mark,
  .cell:not(.taken):not(.win):hover::after {
    font-size: 2.6rem;
  }

  .app-title {
    font-size: 1.4rem;
  }
}

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