/* ============================================================
   PicPuzzle — Premium iOS-style design system
   ============================================================ */

@import url('https://fonts.googleapis.com/css2?family=Nunito:wght@400;600;700;800;900&display=swap');

/* ── CSS Variables / Design Tokens ─────────────────────────── */
:root {
  --font: 'Nunito', system-ui, sans-serif;

  /* Dark theme (default) */
  --bg-base: #0d0d1a;
  --bg-surface: rgba(255,255,255,0.06);
  --bg-card: rgba(255,255,255,0.08);
  --bg-elevated: rgba(255,255,255,0.12);
  --bg-overlay: rgba(0,0,0,0.6);

  --accent-primary: #8b5cf6;
  --accent-secondary: #06b6d4;
  --accent-success: #10b981;
  --accent-danger: #f43f5e;
  --accent-warning: #f59e0b;
  --accent-gold: #fbbf24;

  --gradient-main: linear-gradient(135deg, #0f0c29 0%, #302b63 50%, #24243e 100%);
  --gradient-card: linear-gradient(135deg, rgba(139,92,246,0.2) 0%, rgba(6,182,212,0.1) 100%);
  --gradient-btn: linear-gradient(135deg, #8b5cf6 0%, #6366f1 100%);
  --gradient-btn-danger: linear-gradient(135deg, #f43f5e 0%, #e11d48 100%);
  --gradient-btn-success: linear-gradient(135deg, #10b981 0%, #059669 100%);
  --gradient-btn-surprise: linear-gradient(135deg, #f59e0b 0%, #d97706 100%);
  --gradient-header: linear-gradient(180deg, rgba(13,13,26,0.98) 0%, rgba(13,13,26,0) 100%);

  --text-primary: #f0f0ff;
  --text-secondary: rgba(240,240,255,0.6);
  --text-muted: rgba(240,240,255,0.35);
  --text-on-accent: #ffffff;

  --border: rgba(255,255,255,0.1);
  --border-accent: rgba(139,92,246,0.4);
  --shadow-sm: 0 2px 8px rgba(0,0,0,0.3);
  --shadow-md: 0 8px 32px rgba(0,0,0,0.4);
  --shadow-lg: 0 20px 60px rgba(0,0,0,0.5);
  --shadow-glow: 0 0 30px rgba(139,92,246,0.35);
  --shadow-tile: 0 4px 16px rgba(0,0,0,0.4);

  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-xl: 32px;
  --radius-full: 9999px;

  --safe-top: env(safe-area-inset-top, 0px);
  --safe-bottom: env(safe-area-inset-bottom, 0px);
  --safe-left: env(safe-area-inset-left, 0px);
  --safe-right: env(safe-area-inset-right, 0px);

  --transition-fast: 0.15s cubic-bezier(0.4,0,0.2,1);
  --transition-med: 0.3s cubic-bezier(0.4,0,0.2,1);
  --transition-slow: 0.5s cubic-bezier(0.4,0,0.2,1);
  --spring: 0.4s cubic-bezier(0.34,1.56,0.64,1);
}

[data-theme="light"] {
  --bg-base: #f0f0ff;
  --bg-surface: rgba(255,255,255,0.7);
  --bg-card: rgba(255,255,255,0.85);
  --bg-elevated: rgba(255,255,255,0.95);
  --bg-overlay: rgba(0,0,0,0.4);

  --gradient-main: linear-gradient(135deg, #e0e7ff 0%, #c7d2fe 50%, #ddd6fe 100%);
  --gradient-card: linear-gradient(135deg, rgba(139,92,246,0.12) 0%, rgba(6,182,212,0.06) 100%);

  --text-primary: #1e1b4b;
  --text-secondary: rgba(30,27,75,0.65);
  --text-muted: rgba(30,27,75,0.4);

  --border: rgba(139,92,246,0.15);
  --border-accent: rgba(139,92,246,0.35);
  --shadow-sm: 0 2px 8px rgba(100,80,200,0.12);
  --shadow-md: 0 8px 32px rgba(100,80,200,0.18);
  --shadow-lg: 0 20px 60px rgba(100,80,200,0.22);
  --shadow-glow: 0 0 30px rgba(139,92,246,0.2);
  --shadow-tile: 0 4px 16px rgba(100,80,200,0.2);
}

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

html {
  height: 100%;
  -webkit-text-size-adjust: 100%;
  touch-action: manipulation;
}

body {
  font-family: var(--font);
  background: var(--bg-base);
  color: var(--text-primary);
  min-height: 100%;
  min-height: 100dvh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  user-select: none;
  -webkit-user-select: none;
  padding-top: var(--safe-top);
  padding-bottom: var(--safe-bottom);
  padding-left: var(--safe-left);
  padding-right: var(--safe-right);
}

/* ── Background ─────────────────────────────────────────────── */
#bg-canvas {
  position: fixed;
  inset: 0;
  background: var(--gradient-main);
  z-index: -2;
}

.bg-orb {
  position: fixed;
  border-radius: 50%;
  filter: blur(80px);
  opacity: 0.25;
  z-index: -1;
  animation: orb-drift 15s ease-in-out infinite alternate;
}
.bg-orb-1 { width: 400px; height: 400px; background: #8b5cf6; top: -100px; left: -100px; animation-delay: 0s; }
.bg-orb-2 { width: 300px; height: 300px; background: #06b6d4; bottom: -80px; right: -80px; animation-delay: -5s; }
.bg-orb-3 { width: 250px; height: 250px; background: #f59e0b; top: 40%; left: 60%; animation-delay: -10s; }

[data-theme="light"] .bg-orb { opacity: 0.12; }

@keyframes orb-drift {
  0% { transform: translate(0,0) scale(1); }
  100% { transform: translate(30px,20px) scale(1.08); }
}

/* ── Screens ─────────────────────────────────────────────────── */
.screen {
  display: none;
  flex-direction: column;
  min-height: 100dvh;
  animation: screen-in 0.4s cubic-bezier(0.4,0,0.2,1) both;
}
.screen.active { display: flex; }

@keyframes screen-in {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Glass Card ─────────────────────────────────────────────── */
.glass {
  background: var(--bg-card);
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
}

.glass-elevated {
  background: var(--bg-elevated);
  backdrop-filter: blur(30px) saturate(200%);
  -webkit-backdrop-filter: blur(30px) saturate(200%);
  border: 1px solid var(--border-accent);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg), var(--shadow-glow);
}

/* ── Buttons ─────────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 24px;
  border: none;
  border-radius: var(--radius-full);
  font-family: var(--font);
  font-size: 16px;
  font-weight: 800;
  letter-spacing: 0.3px;
  cursor: pointer;
  transition: transform var(--transition-fast), box-shadow var(--transition-fast), opacity var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
  outline: none;
  position: relative;
  overflow: hidden;
  white-space: nowrap;
}

.btn::after {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0.15);
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.btn:active { transform: scale(0.94); }
.btn:active::after { opacity: 1; }

.btn-primary {
  background: var(--gradient-btn);
  color: #fff;
  box-shadow: 0 4px 20px rgba(139,92,246,0.5);
}
.btn-primary:hover { box-shadow: 0 6px 28px rgba(139,92,246,0.7); transform: translateY(-1px); }

.btn-surprise {
  background: var(--gradient-btn-surprise);
  color: #fff;
  box-shadow: 0 4px 20px rgba(245,158,11,0.5);
}
.btn-surprise:hover { box-shadow: 0 6px 28px rgba(245,158,11,0.7); transform: translateY(-1px); }

.btn-success {
  background: var(--gradient-btn-success);
  color: #fff;
  box-shadow: 0 4px 20px rgba(16,185,129,0.5);
}

.btn-danger {
  background: var(--gradient-btn-danger);
  color: #fff;
  box-shadow: 0 4px 20px rgba(244,63,94,0.4);
}

.btn-ghost {
  background: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
}
.btn-ghost:hover { background: var(--bg-elevated); }

.btn-icon {
  width: 44px;
  height: 44px;
  padding: 0;
  border-radius: var(--radius-md);
  font-size: 20px;
  background: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border);
}

.btn-lg { padding: 18px 32px; font-size: 18px; }
.btn-sm { padding: 10px 18px; font-size: 14px; }
.btn-full { width: 100%; }

/* ── Typography ─────────────────────────────────────────────── */
h1 { font-size: clamp(28px, 8vw, 38px); font-weight: 900; line-height: 1.1; }
h2 { font-size: clamp(20px, 5vw, 26px); font-weight: 800; }
h3 { font-size: 18px; font-weight: 700; }
p  { line-height: 1.6; }

.text-gradient {
  background: linear-gradient(135deg, #c4b5fd, #67e8f9, #a78bfa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
[data-theme="light"] .text-gradient {
  background: linear-gradient(135deg, #7c3aed, #0891b2, #6d28d9);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.text-secondary { color: var(--text-secondary); }
.text-muted { color: var(--text-muted); }
.text-center { text-align: center; }

/* ══════════════════════════════════════════════════════════════
   HOME SCREEN
   ══════════════════════════════════════════════════════════════ */
#screen-home {
  padding: 24px 20px;
  gap: 0;
  align-items: stretch;
}

.home-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 0 16px;
}

.home-logo {
  display: flex;
  align-items: center;
  gap: 10px;
}

.home-logo-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-glow);
}

.home-logo-icon img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.home-logo-text {
  font-size: 22px;
  font-weight: 900;
}

.home-header-actions {
  display: flex;
  gap: 8px;
}

/* Hero */
.home-hero {
  text-align: center;
  padding: 20px 0 28px;
}

.home-hero h1 { margin-bottom: 8px; }
.home-hero p { color: var(--text-secondary); font-size: 15px; }

/* Image source section */
.section-label {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 10px;
}

.home-section {
  margin-bottom: 22px;
}

.image-preview-area {
  position: relative;
  width: 100%;
  height: 180px;
  border-radius: var(--radius-lg);
  background: var(--bg-surface);
  border: 2px dashed var(--border-accent);
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 12px;
  transition: border-color var(--transition-med);
  cursor: pointer;
}

.image-preview-area.has-image {
  border-style: solid;
  border-color: var(--accent-primary);
}

.image-preview-area img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.preview-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.45);
  display: flex;
  align-items: center;
  justify-content: center;
}

.preview-placeholder {
  font-size: 40px;
  opacity: 0.3;
}

.preview-placeholder-text {
  font-size: 13px;
  color: var(--text-muted);
  font-weight: 700;
}

.image-btns {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 10px;
}

/* Difficulty Pills */
.diff-pills {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.diff-pill {
  flex: 1;
  min-width: 60px;
  padding: 10px 6px;
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  border: 1.5px solid var(--border);
  font-family: var(--font);
  font-weight: 700;
  font-size: 12px;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  text-align: center;
  -webkit-tap-highlight-color: transparent;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

.diff-pill:active { transform: scale(0.93); }

.diff-pill .diff-grid {
  font-size: 18px;
  font-weight: 900;
  line-height: 1;
}

.diff-pill .diff-name {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.diff-pill.selected {
  background: linear-gradient(135deg, rgba(139,92,246,0.3), rgba(6,182,212,0.2));
  border-color: var(--accent-primary);
  color: var(--text-primary);
  box-shadow: 0 0 16px rgba(139,92,246,0.3);
}

/* Mode toggle */
.mode-toggle {
  display: flex;
  gap: 0;
  background: var(--bg-surface);
  border-radius: var(--radius-full);
  padding: 4px;
  border: 1px solid var(--border);
}

.mode-btn {
  flex: 1;
  padding: 10px 16px;
  border: none;
  border-radius: var(--radius-full);
  font-family: var(--font);
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition-med);
  color: var(--text-secondary);
  background: transparent;
  -webkit-tap-highlight-color: transparent;
}

.mode-btn.selected {
  background: var(--gradient-btn);
  color: #fff;
  box-shadow: 0 2px 12px rgba(139,92,246,0.5);
}

/* Start button area */
.home-start {
  margin-top: auto;
  padding-top: 16px;
}

/* ══════════════════════════════════════════════════════════════
   GAME SCREEN
   ══════════════════════════════════════════════════════════════ */
#screen-game {
  padding: 0;
}

.game-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 20px;
  padding-top: calc(14px + var(--safe-top));
  background: var(--gradient-header);
  gap: 12px;
  position: relative;
  z-index: 10;
}

.game-stats {
  display: flex;
  gap: 10px;
  flex: 1;
  justify-content: center;
}

.stat-pill {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border-radius: var(--radius-full);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  font-weight: 800;
  font-size: 14px;
}

.stat-pill .stat-icon { font-size: 16px; }
.stat-pill .stat-val { color: var(--text-primary); }

.game-actions {
  display: flex;
  gap: 8px;
}

/* Board */
.game-board-wrap {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px 16px;
}

#puzzle-board {
  display: grid;
  gap: 4px;
  width: min(90vw, 90vh - 160px);
  height: min(90vw, 90vh - 160px);
  aspect-ratio: 1;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-lg), var(--shadow-glow);
  border: 2px solid var(--border-accent);
  position: relative;
}

/* Tiles */
.tile {
  position: absolute;
  background-size: cover;
  background-position: center;
  border-radius: 4px;
  cursor: pointer;
  transition: transform var(--spring), box-shadow var(--transition-fast);
  box-shadow: var(--shadow-tile);
  border: 1px solid rgba(255,255,255,0.08);
  -webkit-tap-highlight-color: transparent;
  will-change: transform;
}

.tile::after {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(255,255,255,0.08) 0%, transparent 60%);
  pointer-events: none;
  border-radius: inherit;
}

.tile:hover { box-shadow: 0 8px 24px rgba(0,0,0,0.5), 0 0 0 2px var(--accent-primary); }
.tile:active { transform: scale(0.96) !important; }

/* While being finger-dragged */
.tile.dragging {
  z-index: 10;
  box-shadow: 0 16px 40px rgba(0,0,0,0.6), 0 0 0 2.5px var(--accent-secondary) !important;
  filter: brightness(1.08);
}

.tile.empty {
  background: rgba(0,0,0,0.3) !important;
  cursor: default;
  box-shadow: inset 0 2px 8px rgba(0,0,0,0.4);
  border: 1px dashed rgba(255,255,255,0.08);
}

.tile.empty::after { display: none; }
.tile.empty:hover { box-shadow: inset 0 2px 8px rgba(0,0,0,0.4); }

.tile.sliding {
  transition: transform 0.18s cubic-bezier(0.34,1.4,0.64,1), box-shadow var(--transition-fast);
}

/* Preview overlay */
.preview-toggle-btn {
  position: fixed;
  bottom: calc(24px + var(--safe-bottom));
  left: 50%;
  transform: translateX(-50%);
  z-index: 20;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.preview-modal {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-overlay);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  animation: fade-in 0.2s ease both;
  padding: 40px 24px;
}

.preview-modal img {
  max-width: 100%;
  max-height: 100%;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
}

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

/* Pause overlay */
.pause-overlay {
  position: fixed;
  inset: 0;
  z-index: 90;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  background: var(--bg-overlay);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  animation: fade-in 0.2s ease both;
  padding: 40px 32px;
}

.pause-overlay h2 { font-size: 36px; }
.pause-overlay .pause-btns { display: flex; flex-direction: column; gap: 12px; width: 100%; max-width: 280px; }

/* ══════════════════════════════════════════════════════════════
   WIN SCREEN
   ══════════════════════════════════════════════════════════════ */
#screen-win {
  padding: 32px 24px;
  align-items: center;
  justify-content: center;
  gap: 24px;
  position: relative;
  overflow: hidden;
}

.win-card {
  width: 100%;
  max-width: 360px;
  padding: 32px 24px;
  text-align: center;
  position: relative;
  z-index: 1;
}

.win-emoji { font-size: 72px; display: block; margin-bottom: 8px; animation: pop-in 0.5s var(--spring) both 0.1s; }
.win-title { margin-bottom: 4px; }
.win-new-record { font-size: 18px; font-weight: 800; color: var(--accent-gold); margin-bottom: 16px; animation: glow-pulse 1.5s ease infinite; }

@keyframes glow-pulse {
  0%,100% { text-shadow: 0 0 10px rgba(251,191,36,0.5); }
  50%      { text-shadow: 0 0 30px rgba(251,191,36,0.9); }
}

.win-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
  margin: 24px 0;
}

.win-stat {
  padding: 16px;
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  border: 1px solid var(--border);
}

.win-stat-val { font-size: 28px; font-weight: 900; color: var(--accent-primary); }
.win-stat-label { font-size: 12px; color: var(--text-muted); font-weight: 700; margin-top: 2px; text-transform: uppercase; letter-spacing: 0.5px; }

.name-input-wrap {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 20px;
}

.name-input-label { font-size: 13px; font-weight: 700; color: var(--text-secondary); text-align: left; }

.name-input {
  width: 100%;
  padding: 14px 18px;
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  border: 1.5px solid var(--border);
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 16px;
  font-weight: 700;
  outline: none;
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
  -webkit-appearance: none;
}

.name-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 3px rgba(139,92,246,0.2);
}

.win-btns { display: flex; flex-direction: column; gap: 10px; }

@keyframes pop-in {
  from { transform: scale(0.3); opacity: 0; }
  to   { transform: scale(1); opacity: 1; }
}

/* Confetti canvas */
#confetti-canvas {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 200;
}

/* ══════════════════════════════════════════════════════════════
   LEADERBOARD SCREEN
   ══════════════════════════════════════════════════════════════ */
#screen-leaderboard {
  padding: 0;
}

.lb-header {
  padding: 20px 20px 16px;
  padding-top: calc(20px + var(--safe-top));
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid var(--border);
}

.lb-header h2 { flex: 1; }

.lb-tabs {
  display: flex;
  gap: 6px;
  padding: 12px 20px;
  overflow-x: auto;
  scrollbar-width: none;
  -ms-overflow-style: none;
}
.lb-tabs::-webkit-scrollbar { display: none; }

.lb-tab {
  flex-shrink: 0;
  padding: 8px 16px;
  border-radius: var(--radius-full);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  font-family: var(--font);
  font-size: 13px;
  font-weight: 700;
  cursor: pointer;
  color: var(--text-secondary);
  transition: all var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.lb-tab.active {
  background: var(--gradient-btn);
  color: #fff;
  border-color: transparent;
  box-shadow: 0 2px 12px rgba(139,92,246,0.4);
}

.lb-list {
  flex: 1;
  overflow-y: auto;
  padding: 8px 20px 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  scrollbar-width: thin;
  scrollbar-color: var(--border) transparent;
}

.lb-item {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 14px 18px;
  border-radius: var(--radius-md);
  background: var(--bg-card);
  border: 1px solid var(--border);
  animation: slide-up 0.3s ease both;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

@keyframes slide-up {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}

.lb-rank {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 900;
  font-size: 14px;
  flex-shrink: 0;
}

.lb-rank-1 { background: linear-gradient(135deg, #fbbf24, #f59e0b); color: #fff; box-shadow: 0 2px 12px rgba(251,191,36,0.5); }
.lb-rank-2 { background: linear-gradient(135deg, #9ca3af, #6b7280); color: #fff; }
.lb-rank-3 { background: linear-gradient(135deg, #cd7c2c, #a85f1d); color: #fff; }
.lb-rank-n { background: var(--bg-surface); color: var(--text-muted); border: 1px solid var(--border); }

.lb-player { flex: 1; font-weight: 700; font-size: 15px; }
.lb-score { font-weight: 800; font-size: 15px; color: var(--accent-primary); }
.lb-moves { font-size: 12px; color: var(--text-muted); font-weight: 600; }

.lb-empty {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 12px;
  color: var(--text-muted);
  padding: 60px 20px;
  font-size: 15px;
  font-weight: 600;
}

.lb-empty-icon { font-size: 56px; opacity: 0.4; }

.lb-footer {
  padding: 16px 20px;
  padding-bottom: calc(16px + var(--safe-bottom));
  border-top: 1px solid var(--border);
  display: flex;
  gap: 10px;
}

/* ══════════════════════════════════════════════════════════════
   SETTINGS SCREEN
   ══════════════════════════════════════════════════════════════ */
#screen-settings {
  padding: 0;
}

.settings-header {
  padding: 20px 20px 16px;
  padding-top: calc(20px + var(--safe-top));
  display: flex;
  align-items: center;
  gap: 12px;
  border-bottom: 1px solid var(--border);
}

.settings-header h2 { flex: 1; }

.settings-body {
  flex: 1;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
  overflow-y: auto;
}

.setting-group {
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  border: 1px solid var(--border);
  overflow: hidden;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  gap: 16px;
  border-bottom: 1px solid var(--border);
  transition: background var(--transition-fast);
}

.setting-row:last-child { border-bottom: none; }

.setting-row-label {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.setting-row-label span:first-child { font-weight: 700; font-size: 15px; }
.setting-row-label span.sub { font-size: 12px; color: var(--text-muted); font-weight: 600; }

/* Toggle switch */
.toggle {
  position: relative;
  width: 52px;
  height: 30px;
  flex-shrink: 0;
}

.toggle input {
  opacity: 0;
  width: 0;
  height: 0;
  position: absolute;
}

.toggle-track {
  position: absolute;
  inset: 0;
  border-radius: var(--radius-full);
  background: var(--bg-surface);
  border: 1px solid var(--border);
  transition: background var(--transition-med);
  cursor: pointer;
}

.toggle-track::after {
  content: '';
  position: absolute;
  width: 22px;
  height: 22px;
  top: 3px;
  left: 4px;
  border-radius: 50%;
  background: var(--text-muted);
  transition: transform var(--spring), background var(--transition-med);
  box-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

.toggle input:checked + .toggle-track {
  background: var(--accent-primary);
  border-color: var(--accent-primary);
}

.toggle input:checked + .toggle-track::after {
  transform: translateX(22px);
  background: #fff;
}

/* Theme selector */
.theme-selector {
  display: flex;
  gap: 8px;
}

.theme-opt {
  flex: 1;
  padding: 10px;
  border-radius: var(--radius-md);
  border: 2px solid var(--border);
  background: var(--bg-surface);
  font-family: var(--font);
  font-size: 13px;
  font-weight: 700;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  transition: all var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.theme-opt.selected {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
  background: rgba(139,92,246,0.1);
}

/* Language selector */
.lang-selector {
  display: flex;
  flex-direction: column;
  gap: 0;
}

.lang-opt {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 20px;
  border-bottom: 1px solid var(--border);
  cursor: pointer;
  transition: background var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
  font-weight: 600;
  font-size: 15px;
}

.lang-opt:last-child { border-bottom: none; }
.lang-opt:active { background: var(--bg-surface); }

.lang-flag { font-size: 22px; }
.lang-name { flex: 1; }
.lang-check { color: var(--accent-primary); font-size: 18px; opacity: 0; transition: opacity var(--transition-fast); }
.lang-opt.selected .lang-check { opacity: 1; }
.lang-opt.selected { color: var(--text-primary); }

/* ══════════════════════════════════════════════════════════════
   LOADING OVERLAY
   ══════════════════════════════════════════════════════════════ */
#loading-overlay {
  position: fixed;
  inset: 0;
  z-index: 300;
  background: var(--bg-overlay);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: none;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
}

#loading-overlay.visible { display: flex; }

.spinner {
  width: 56px;
  height: 56px;
  border: 4px solid var(--border);
  border-top-color: var(--accent-primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading-text {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-secondary);
}

/* ══════════════════════════════════════════════════════════════
   TOAST NOTIFICATION
   ══════════════════════════════════════════════════════════════ */
#toast-container {
  position: fixed;
  top: calc(16px + var(--safe-top));
  left: 50%;
  transform: translateX(-50%);
  z-index: 500;
  display: flex;
  flex-direction: column;
  gap: 8px;
  pointer-events: none;
  width: calc(100% - 40px);
  max-width: 360px;
}

.toast {
  padding: 14px 18px;
  border-radius: var(--radius-md);
  background: var(--bg-elevated);
  border: 1px solid var(--border-accent);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  font-weight: 700;
  font-size: 14px;
  box-shadow: var(--shadow-md);
  animation: toast-in 0.3s var(--spring) both;
  text-align: center;
}

.toast.out { animation: toast-out 0.3s ease both; }

@keyframes toast-in {
  from { opacity: 0; transform: translateY(-20px) scale(0.9); }
  to   { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes toast-out {
  from { opacity: 1; transform: translateY(0) scale(1); }
  to   { opacity: 0; transform: translateY(-20px) scale(0.9); }
}

/* ══════════════════════════════════════════════════════════════
   BOTTOM NAV
   ══════════════════════════════════════════════════════════════ */
.bottom-nav {
  display: flex;
  border-top: 1px solid var(--border);
  background: var(--bg-surface);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding-bottom: var(--safe-bottom);
}

.nav-item {
  flex: 1;
  padding: 12px 8px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  border: none;
  background: transparent;
  color: var(--text-muted);
  font-family: var(--font);
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.3px;
  transition: color var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.nav-item.active { color: var(--accent-primary); }
.nav-item .nav-icon { font-size: 24px; }

/* ══════════════════════════════════════════════════════════════
   SCROLLBAR
   ══════════════════════════════════════════════════════════════ */
::-webkit-scrollbar { width: 4px; height: 4px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--border); border-radius: 4px; }

/* ══════════════════════════════════════════════════════════════
   UTILITY
   ══════════════════════════════════════════════════════════════ */
.hidden { display: none !important; }
.flex { display: flex; }
.flex-col { flex-direction: column; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.mt-auto { margin-top: auto; }

/* ══════════════════════════════════════════════════════════════
   RESPONSIVE TWEAKS
   ══════════════════════════════════════════════════════════════ */
@media (min-width: 480px) {
  #screen-home { max-width: 430px; margin: 0 auto; }
  #screen-win .win-card { max-width: 400px; }
}

@media (max-height: 700px) {
  .home-hero { padding: 10px 0 16px; }
  #puzzle-board {
    width: min(88vw, calc(100dvh - 140px));
    height: min(88vw, calc(100dvh - 140px));
  }
}