:root {
  --bg-color: #0f172a;
  --card-bg: #1e293b;
  --accent-color: #6366f1;
  --accent-hover: #4f46e5;
  --gold-color: #f59e0b;
  --success-color: #10b981;
  --danger-color: #ef4444;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --tile-bg: #334155;
  --tile-active: #475569;
  --border-color: #334155;
  --font-main: 'Outfit', sans-serif;
  --font-mono: 'Space Mono', monospace;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background-color: var(--bg-color);
  color: var(--text-main);
  font-family: var(--font-main);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 1rem 0.5rem;
  overflow-x: hidden;
}

.app-container {
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

/* Navbar */
.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.25rem 0;
}

.logo-text {
  font-size: 1.7rem;
  font-weight: 800;
  letter-spacing: -0.5px;
}

.logo-highlight {
  color: var(--gold-color);
}

.nav-controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

/* Buttons */
.btn-primary {
  background: linear-gradient(135deg, var(--accent-color), #4338ca);
  color: white;
  border: none;
  padding: 0.75rem 1.1rem;
  border-radius: 12px;
  font-weight: 700;
  font-size: 0.95rem;
  cursor: pointer;
  transition: transform 0.1s ease, box-shadow 0.2s ease;
}

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

.btn-primary:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  box-shadow: none;
}

.btn-secondary {
  background: var(--tile-bg);
  color: var(--text-main);
  border: 1px solid var(--border-color);
  padding: 0.6rem 0.9rem;
  border-radius: 10px;
  font-weight: 600;
  cursor: pointer;
}

.btn-icon {
  background: var(--tile-bg);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 0.45rem 0.75rem;
  font-size: 1.1rem;
  cursor: pointer;
}

.btn-sm {
  font-size: 0.85rem;
  padding: 0.4rem 0.8rem;
}

.btn-lg {
  padding: 0.85rem;
  width: 100%;
  font-size: 0.95rem;
}

.btn-block {
  width: 100%;
}

.btn-start {
  width: 100%;
  font-size: 1.1rem;
  padding: 0.95rem;
  margin-top: 0.8rem;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.4);
}

/* Main Card */
.game-card {
  background: var(--card-bg);
  border-radius: 18px;
  padding: 1.25rem 1rem;
  border: 1px solid var(--border-color);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.4);
}

/* Mode Switcher Bar */
.mode-toggle-bar {
  display: flex;
  background: rgba(15, 23, 42, 0.7);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 0.2rem;
  margin-bottom: 0.8rem;
  gap: 0.25rem;
}

.mode-btn {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-family: var(--font-main);
  font-weight: 800;
  font-size: 0.8rem;
  padding: 0.5rem 0.4rem;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.3rem;
  transition: all 0.2s ease;
}

.mode-btn.active {
  background: linear-gradient(135deg, var(--accent-color), #4338ca);
  color: white;
  box-shadow: 0 3px 10px rgba(99, 102, 241, 0.35);
}

.mode-icon {
  font-size: 0.95rem;
}

.date-badge {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  font-weight: 600;
  margin-bottom: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 1px;
}

/* Pre-Start Screen */
.prestart-box {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.8rem;
  padding: 0.4rem 0;
}

.lock-icon {
  font-size: 2.5rem;
}

.prestart-box h2 {
  font-size: 1.25rem;
  font-weight: 700;
}

.description {
  color: var(--text-muted);
  font-size: 0.9rem;
  line-height: 1.35;
}

.preview-tiles-hidden {
  display: flex;
  gap: 0.4rem;
  margin: 0.5rem 0;
}

.tile-hidden {
  width: 40px;
  height: 40px;
  background: var(--tile-bg);
  border: 2px dashed var(--border-color);
  border-radius: 10px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-muted);
}

/* HUD Bar */
.hud-bar {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.6rem;
  margin-bottom: 0.8rem;
}

.hud-item {
  background: rgba(15, 23, 42, 0.6);
  padding: 0.6rem 0.4rem;
  border-radius: 10px;
  text-align: center;
  border: 1px solid var(--border-color);
}

.hud-label {
  display: block;
  font-size: 0.68rem;
  color: var(--text-muted);
  font-weight: 700;
  letter-spacing: 1px;
}

.hud-value {
  font-family: var(--font-mono);
  font-size: 1.3rem;
  font-weight: 700;
}

.target-val {
  color: var(--gold-color);
}

.timer-val {
  color: var(--text-main);
}

.solutions-hud-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.8rem;
}

.solutions-badge {
  flex: 1;
  text-align: center;
  background: rgba(99, 102, 241, 0.15);
  border: 1px solid rgba(99, 102, 241, 0.3);
  padding: 0.45rem 0.6rem;
  border-radius: 8px;
  font-size: 0.8rem;
  color: var(--accent-color);
}

.btn-finish-midway {
  font-size: 0.75rem;
  padding: 0.45rem 0.65rem;
  background: rgba(239, 68, 68, 0.15);
  border: 1px solid rgba(239, 68, 68, 0.4);
  color: #fca5a5;
  border-radius: 8px;
  white-space: nowrap;
  font-weight: 700;
  cursor: pointer;
  transition: background 0.2s ease;
}

.btn-finish-midway:hover {
  background: rgba(239, 68, 68, 0.25);
  color: #fee2e2;
}

/* Tiles Section */
.section-label {
  display: block;
  font-size: 0.72rem;
  color: var(--text-muted);
  font-weight: 700;
  margin-bottom: 0.4rem;
}

.tiles-grid {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.35rem;
  margin-bottom: 0.8rem;
  flex-wrap: nowrap; /* Guarantees all 5 tiles stay on 1 row */
  width: 100%;
}

.num-tile {
  flex: 1;
  max-width: 54px;
  aspect-ratio: 1;
  min-width: 0;
  width: 100%;
  height: auto;
  background: var(--tile-bg);
  border: 2px solid var(--border-color);
  border-radius: 10px;
  font-size: clamp(1rem, 4vw, 1.25rem);
  font-weight: 800;
  color: var(--text-main);
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  user-select: none;
  transition: transform 0.1s ease, border-color 0.2s ease, background 0.2s ease;
}

.num-tile:hover {
  border-color: var(--accent-color);
}

.num-tile.used {
  opacity: 0.3;
  pointer-events: none;
  border-style: dashed;
}

/* Operators Deck */
.operators-deck {
  display: flex;
  justify-content: space-between;
  gap: 0.35rem;
  margin-bottom: 0.8rem;
}

.op-btn {
  flex: 1;
  height: 40px;
  background: #334155;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--gold-color);
  cursor: pointer;
}

.op-btn:active {
  background: var(--accent-color);
  color: white;
}

/* Equation Dock */
.equation-dock {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}

.equation-box {
  min-height: 46px;
  background: rgba(15, 23, 42, 0.8);
  border: 2px solid var(--border-color);
  border-radius: 10px;
  padding: 0.6rem;
  display: flex;
  align-items: center;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--text-main);
  overflow-x: auto;
  white-space: nowrap;
}

.placeholder-text {
  color: var(--text-muted);
  font-size: 0.8rem;
  font-family: var(--font-main);
}

.dock-actions {
  display: flex;
  gap: 0.4rem;
}

.btn-dock {
  flex: 1;
  padding: 0.55rem 0.5rem;
}

/* Feedback Banner */
.feedback-banner {
  margin-top: 0.8rem;
  padding: 0.65rem;
  border-radius: 8px;
  text-align: center;
  font-size: 0.85rem;
  font-weight: 600;
}

.feedback-banner.success {
  background: rgba(16, 185, 129, 0.2);
  border: 1px solid var(--success-color);
  color: var(--success-color);
}

.feedback-banner.error {
  background: rgba(239, 68, 68, 0.2);
  border: 1px solid var(--danger-color);
  color: var(--danger-color);
}

.auth-error-banner {
  background: rgba(239, 68, 68, 0.2);
  border: 1px solid var(--danger-color);
  color: #fca5a5;
  padding: 0.65rem;
  border-radius: 8px;
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 0.8rem;
  text-align: center;
}

/* Summary Screen */
.summary-box {
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
  padding: 0.2rem 0;
}

.summary-badge {
  background: rgba(16, 185, 129, 0.15);
  color: var(--success-color);
  border: 1px solid var(--success-color);
  border-radius: 10px;
  padding: 0.35rem 0.8rem;
  font-weight: 700;
  font-size: 0.8rem;
  display: inline-block;
  align-self: center;
}

.summary-target-title {
  font-size: 1.35rem;
  font-weight: 800;
}

.highlight-gold {
  color: var(--gold-color);
}

.summary-stats-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.6rem;
}

.stat-card {
  background: rgba(15, 23, 42, 0.6);
  padding: 0.65rem 0.4rem;
  border-radius: 10px;
  border: 1px solid var(--border-color);
  text-align: center;
}

.stat-label {
  font-size: 0.68rem;
  color: var(--text-muted);
  font-weight: 700;
  letter-spacing: 1px;
  display: block;
  margin-bottom: 0.15rem;
}

.stat-val {
  font-family: var(--font-mono);
  font-size: 1.25rem;
  font-weight: 700;
}

.solutions-list-box {
  text-align: left;
}

.solutions-list {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
  max-height: 140px;
  overflow-y: auto;
  background: rgba(15, 23, 42, 0.8);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 0.6rem;
}

.solution-item {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--success-color);
  background: rgba(16, 185, 129, 0.1);
  padding: 0.45rem 0.7rem;
  border-radius: 6px;
  border: 1px solid rgba(16, 185, 129, 0.3);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.no-solutions-text {
  color: var(--text-muted);
  font-size: 0.85rem;
  font-style: italic;
  text-align: center;
  padding: 0.4rem;
}

.summary-actions {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.share-toast {
  background: var(--success-color);
  color: #0f172a;
  font-weight: 700;
  padding: 0.5rem;
  border-radius: 8px;
  font-size: 0.85rem;
  text-align: center;
}

/* Modals & Anti-Cheat Blur Overlay */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: rgba(15, 23, 42, 0.8);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 0.75rem;
  z-index: 1000;
  overflow-y: auto;
}

.modal-card {
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 18px;
  padding: 1.35rem 1rem;
  width: 100%;
  max-width: 420px;
  position: relative;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.6);
  max-height: 85vh;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

.modal-wide {
  max-width: 520px;
}

.pause-card {
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 0.8rem;
}

.modal-icon {
  font-size: 2.2rem;
}

.solution-highlight {
  background: rgba(16, 185, 129, 0.15);
  border: 1px dashed var(--success-color);
  padding: 0.75rem;
  border-radius: 10px;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--success-color);
}

.pause-note {
  font-size: 0.85rem;
  color: var(--text-muted);
}

.modal-actions {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.modal-close {
  position: absolute;
  top: 0.7rem;
  right: 0.9rem;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 1.6rem;
  cursor: pointer;
  z-index: 10;
}

/* Leaderboard Mode Selector */
.lb-mode-selector {
  display: flex;
  gap: 0.35rem;
  margin-top: 0.6rem;
  margin-bottom: 0.2rem;
}

.lb-mode-btn {
  flex: 1;
  background: var(--tile-bg);
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  font-family: var(--font-main);
  font-weight: 700;
  font-size: 0.8rem;
  padding: 0.45rem;
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.lb-mode-btn.active {
  background: var(--gold-color);
  color: #0f172a;
  border-color: var(--gold-color);
  box-shadow: 0 2px 8px rgba(245, 158, 11, 0.3);
}

/* Leaderboard Tabs */
.lb-tabs {
  display: flex;
  gap: 0.35rem;
  margin-top: 0.5rem;
  margin-bottom: 0.6rem;
  background: rgba(15, 23, 42, 0.6);
  padding: 0.25rem;
  border-radius: 10px;
  border: 1px solid var(--border-color);
}

.lb-tab-btn {
  flex: 1;
  background: transparent;
  border: none;
  color: var(--text-muted);
  font-family: var(--font-main);
  font-weight: 700;
  font-size: 0.8rem;
  padding: 0.45rem 0.4rem;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.2s ease;
}

.lb-tab-btn.active {
  background: var(--accent-color);
  color: white;
  box-shadow: 0 2px 8px rgba(99, 102, 241, 0.4);
}

/* Forms */
.input-field {
  width: 100%;
  padding: 0.75rem 0.9rem;
  border-radius: 8px;
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  color: var(--text-main);
  font-family: var(--font-main);
  font-size: 0.9rem;
  margin-bottom: 0.6rem;
}

.checkbox-label {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.8rem;
  cursor: pointer;
}

.auth-switch {
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.8rem;
}

.auth-switch a {
  color: var(--accent-color);
  text-decoration: none;
  font-weight: 600;
}

/* Leaderboard Table */
.leaderboard-table-container {
  max-height: 280px;
  overflow-y: auto;
  margin-top: 0.4rem;
}

.lb-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

.lb-table th, .lb-table td {
  padding: 0.6rem 0.4rem;
  text-align: left;
  border-bottom: 1px solid var(--border-color);
}

.lb-table th {
  color: var(--text-muted);
  font-size: 0.7rem;
  text-transform: uppercase;
}

.hidden {
  display: none !important;
}

/* Short Vertical Viewport Optimization (iPhone SE, Safari address bar visible) */
@media (max-height: 720px), (max-width: 480px) {
  body {
    align-items: flex-start;
    padding: 0.5rem 0.5rem 1.5rem 0.5rem;
  }
  .app-container {
    gap: 0.5rem;
  }
  .game-card {
    padding: 1rem 0.8rem;
  }
  .modal-card {
    padding: 1.1rem 0.85rem;
    max-height: 88vh;
  }
  .input-field {
    padding: 0.65rem 0.8rem;
    font-size: 0.88rem;
  }
}