/* ============================================================
   DESIGN TOKENS
   ============================================================ */
:root {
  --bg-primary: #0D1117;
  --bg-secondary: #161B22;
  --bg-tertiary: #21262D;
  --text-primary: #F0F6FC;
  --text-secondary: #8B949E;
  --text-muted: #484F58;
  --accent: #3B82F6;
  --accent-glow: rgba(59, 130, 246, 0.3);
  --border: #30363D;
  --btn-bg: #21262D;
  --btn-active: #30363D;
  --overlay-bg: rgba(0, 0, 0, 0.85);
  --board-bg: #0A0E14;

  --cell-empty: #161B22;
  --cell-filled: #3B82F6;
  --cell-marked: transparent;
  --clue-satisfied: #484F58;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #FFFFFF;
    --bg-secondary: #F6F8FA;
    --bg-tertiary: #E9ECF0;
    --text-primary: #1B1E28;
    --text-secondary: #57606A;
    --text-muted: #8C959F;
    --accent: #3182F6;
    --accent-glow: rgba(49, 130, 246, 0.2);
    --border: #D0D7DE;
    --btn-bg: #E9ECF0;
    --btn-active: #D0D7DE;
    --overlay-bg: rgba(255, 255, 255, 0.9);
    --board-bg: #F0F2F5;

    --cell-empty: #E9ECF0;
    --cell-filled: #3182F6;
    --cell-marked: transparent;
    --clue-satisfied: #C0C8D0;
  }
}

/* ============================================================
   RESET & BASE
   ============================================================ */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  height: 100dvh;
  overflow: hidden;
  touch-action: none;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Pretendard', 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  -webkit-tap-highlight-color: transparent;
  user-select: none;
  -webkit-user-select: none;
}

/* ============================================================
   OVERLAYS
   ============================================================ */
.overlay {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--overlay-bg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  padding: 24px;
  animation: fadeIn 0.25s ease;
}

.overlay.hidden {
  display: none;
}

@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

@keyframes slideUp {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

.overlay-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  width: 100%;
  max-width: 320px;
  animation: slideUp 0.3s ease;
}

.game-title {
  font-size: 48px;
  font-weight: 900;
  letter-spacing: 0.08em;
  background: linear-gradient(135deg, #3B82F6, #8B5CF6, #EC4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  text-align: center;
}

.overlay-icon {
  font-size: 56px;
  line-height: 1;
}

.overlay-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--text-primary);
}

.overlay-desc {
  font-size: 15px;
  color: var(--text-secondary);
  text-align: center;
  line-height: 1.5;
}

.overlay-stats {
  font-size: 14px;
  color: var(--text-muted);
  min-height: 20px;
}

.win-stats {
  width: 100%;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.win-stat-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.win-stat-label {
  font-size: 14px;
  color: var(--text-secondary);
}

.win-stat-value {
  font-size: 20px;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

.new-record {
  font-size: 18px;
  font-weight: 700;
  color: #F59E0B;
  text-align: center;
  animation: pulse 0.8s ease infinite alternate;
}

.new-record.hidden {
  display: none;
}

@keyframes pulse {
  from { opacity: 0.7; transform: scale(0.97); }
  to   { opacity: 1;   transform: scale(1.03); }
}

/* ============================================================
   DIFFICULTY SELECTOR
   ============================================================ */
.difficulty-selector {
  display: flex;
  gap: 8px;
  width: 100%;
}

.diff-btn {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 12px 8px;
  background: var(--bg-tertiary);
  border: 2px solid var(--border);
  border-radius: 12px;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s, box-shadow 0.15s, transform 0.1s;
  font-family: inherit;
}

.diff-btn:hover {
  background: var(--btn-active);
}

.diff-btn:active {
  transform: scale(0.96);
}

.diff-btn.selected {
  border-color: var(--accent);
  box-shadow: 0 0 12px var(--accent-glow);
  background: var(--bg-secondary);
}

.diff-label {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
}

.diff-info {
  font-size: 11px;
  color: var(--text-muted);
  white-space: nowrap;
}

/* ============================================================
   BUTTONS
   ============================================================ */
.btn-primary {
  width: 100%;
  padding: 14px 24px;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 12px;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  transition: opacity 0.15s, transform 0.1s, box-shadow 0.15s;
  box-shadow: 0 0 0 0 var(--accent-glow);
  font-family: inherit;
}

.btn-primary:hover {
  opacity: 0.92;
  box-shadow: 0 0 16px var(--accent-glow);
}

.btn-primary:active {
  transform: scale(0.97);
  opacity: 0.85;
}

.btn-secondary {
  width: 100%;
  padding: 12px 24px;
  background: var(--btn-bg);
  color: var(--text-secondary);
  border: 1px solid var(--border);
  border-radius: 12px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
  font-family: inherit;
}

.btn-secondary:hover {
  background: var(--btn-active);
}

.btn-secondary:active {
  transform: scale(0.97);
}

/* ============================================================
   GAME LAYOUT
   ============================================================ */
.game-wrapper {
  display: flex;
  flex-direction: column;
  width: 100%;
  max-width: 520px;
  height: 100dvh;
  padding: env(safe-area-inset-top, 0) env(safe-area-inset-right, 0) env(safe-area-inset-bottom, 0) env(safe-area-inset-left, 0);
}

/* ============================================================
   HEADER
   ============================================================ */
.game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px 12px;
  border-bottom: 1px solid var(--border);
  background: var(--bg-secondary);
  flex-shrink: 0;
}

.header-title {
  font-size: 20px;
  font-weight: 900;
  letter-spacing: 0.1em;
  background: linear-gradient(135deg, #3B82F6, #8B5CF6, #EC4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.header-stats {
  display: flex;
  gap: 10px;
  align-items: center;
}

.stat-pill {
  display: flex;
  align-items: center;
  gap: 5px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 5px 12px;
  min-width: 64px;
}

.stat-icon {
  font-size: 14px;
  line-height: 1;
}

.stat-value {
  font-size: 15px;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
  min-width: 28px;
}

/* ============================================================
   NONOGRAM BOARD
   ============================================================ */
.board-container {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--board-bg);
  overflow: hidden;
  padding: 8px;
}

.nonogram-board {
  display: grid;
  gap: 0;
  width: fit-content;
  max-width: 100%;
  max-height: 100%;
}

.corner-spacer {
  grid-area: 1 / 1 / 2 / 2;
}

/* ============================================================
   CLUES
   ============================================================ */
.col-clues {
  grid-area: 1 / 2 / 2 / 3;
  display: flex;
  flex-direction: row;
}

.col-clue {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: flex-end;
  gap: 0;
  padding: 2px 0 4px;
}

.col-clue span {
  font-size: var(--clue-font);
  font-weight: 700;
  color: var(--text-secondary);
  line-height: 1.5;
  min-height: 1.5em;
}

.col-clue span.satisfied {
  color: var(--clue-satisfied);
}

.row-clues {
  grid-area: 2 / 1 / 3 / 2;
  display: flex;
  flex-direction: column;
}

.row-clue {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 2px;
  padding: 0 6px 0 2px;
}

.row-clue span {
  font-size: var(--clue-font);
  min-width: 1.4em;
  text-align: center;
  font-weight: 700;
  color: var(--text-secondary);
  line-height: 1.3;
}

.row-clue span.satisfied {
  color: var(--clue-satisfied);
}

/* ============================================================
   GRID
   ============================================================ */
.grid {
  grid-area: 2 / 2 / 3 / 3;
  display: grid;
  gap: 1px;
  background: var(--border);
  border: 2px solid var(--text-muted);
}

.grid-line-v {
  pointer-events: none;
}

.cell {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background 0.08s, transform 0.06s;
  background: var(--cell-empty);
  position: relative;
  -webkit-tap-highlight-color: transparent;
}

.cell:active {
  transform: scale(0.9);
}

.cell.filled {
  background: var(--cell-filled);
}

.cell.marked::after {
  content: '✕';
  font-size: var(--mark-font);
  font-weight: 700;
  color: var(--text-muted);
  line-height: 1;
}

/* 5x5 thick border lines */
.cell.border-right {
  border-right: 2px solid var(--text-muted);
}

.cell.border-bottom {
  border-bottom: 2px solid var(--text-muted);
}

/* Win animation */
.cell.win-pop {
  animation: winCellPop 0.4s ease forwards;
}

@keyframes winCellPop {
  0%   { transform: scale(1); }
  50%  { transform: scale(1.15); }
  100% { transform: scale(1); }
}

/* Error flash */
.cell.error {
  animation: errorFlash 0.5s ease;
}

@keyframes errorFlash {
  0%, 100% { background: var(--cell-empty); }
  25%      { background: #EF4444; }
  50%      { background: var(--cell-empty); }
  75%      { background: #EF4444; }
}

/* ============================================================
   FOOTER
   ============================================================ */
.game-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  border-top: 1px solid var(--border);
  background: var(--bg-secondary);
  gap: 12px;
  flex-shrink: 0;
}

.mode-toggle {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  background: var(--btn-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  cursor: pointer;
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 600;
  transition: background 0.15s, border-color 0.15s, box-shadow 0.15s;
  font-family: inherit;
  flex: 1;
}

.mode-toggle:hover {
  background: var(--btn-active);
}

.mode-toggle:active {
  transform: scale(0.97);
}

.mode-toggle.mark-mode {
  border-color: #F59E0B;
  box-shadow: 0 0 8px rgba(245, 158, 11, 0.25);
}

.mode-icon {
  font-size: 18px;
  line-height: 1;
}

.mode-label {
  color: var(--text-secondary);
  font-size: 13px;
}

.btn-icon {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 10px 16px;
  background: var(--btn-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  cursor: pointer;
  color: var(--text-primary);
  font-size: 18px;
  font-weight: 600;
  transition: background 0.15s, transform 0.1s;
  font-family: inherit;
}

.btn-icon .btn-text {
  font-size: 13px;
  color: var(--text-secondary);
}

.btn-icon:hover {
  background: var(--btn-active);
}

.btn-icon:active {
  transform: scale(0.95);
}

/* ============================================================
   SCROLLBAR HIDE
   ============================================================ */
::-webkit-scrollbar { display: none; }