:root {
  /* Color Palette - Dark Theme (Default) */
  --bg-body: #0f172a;
  --bg-surface: #1e293b;
  --bg-surface-hover: #334155;
  --primary: #3b82f6;
  --primary-hover: #2563eb;
  --secondary: #8b5cf6;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --border-color: #334155;
  --success: #10b981;
  --warning: #f59e0b;
  --danger: #ef4444;
  --cell-bg: #475569;
  --cell-border: rgba(255, 255, 255, 0.1);

  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;

  /* Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;

  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
}

[data-theme="light"] {
  /* Color Palette - Light Theme */
  --bg-body: #f1f5f9;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f8fafc;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --secondary: #7c3aed;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --border-color: #e2e8f0;
  --success: #059669;
  --warning: #d97706;
  --danger: #dc2626;
  --cell-bg: #cbd5e1;
  --cell-border: rgba(0, 0, 0, 0.1);
  
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.05), 0 2px 4px -2px rgb(0 0 0 / 0.05);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.05), 0 4px 6px -4px rgb(0 0 0 / 0.05);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
  background-color: var(--bg-body);
  color: var(--text-main);
  line-height: 1.5;
  min-height: 100vh;
}

/* Layout */
.app-container {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

.app-header {
  padding: var(--spacing-lg) 0;
  text-align: center;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: var(--spacing-lg);
}

.app-header h1 {
  margin: 0;
  font-size: 2rem;
  font-weight: 700;
  background: linear-gradient(to right, var(--primary), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* Header Content */
.header-content {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-md);
  position: relative;
}

/* Theme Toggle */
.theme-toggle {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-main);
  transition: all 0.2s;
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
}

.theme-toggle:hover {
  background: var(--bg-surface-hover);
  color: var(--primary);
}

.icon-sun, .icon-moon {
  font-size: 1.2rem;
  line-height: 1;
}

[data-theme="light"] .icon-sun {
  display: none;
}

[data-theme="dark"] .icon-moon {
  display: none;
}

/* Default to dark mode behavior if no attribute present (fallback) */
:root:not([data-theme]) .icon-moon {
  display: none;
}

.subtitle {
  margin: var(--spacing-xs) 0 0;
  color: var(--text-muted);
  font-size: 1rem;
}

.main-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xl);
  padding-bottom: var(--spacing-xl);
}

.app-footer {
  padding: var(--spacing-md) 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.875rem;
  border-top: 1px solid var(--border-color);
  margin-top: auto;
}

/* Control Panel */
.control-panel {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.panel-header {
  background-color: rgba(0, 0, 0, 0.05);
  padding: var(--spacing-md) var(--spacing-lg);
  border-bottom: 1px solid var(--border-color);
}

.panel-header h2 {
  margin: 0;
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-main);
}

.panel-body {
  padding: var(--spacing-lg);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
}

/* Format Selector */
.format-selector {
  display: flex;
  align-items: center;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
}

.label-text {
  font-weight: 600;
  color: var(--text-muted);
}

.radio-label {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  cursor: pointer;
  user-select: none;
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  transition: background-color 0.2s;
}

.radio-label:hover {
  background-color: var(--bg-surface-hover);
}

.radio-label input {
  display: none;
}

.radio-custom {
  width: 18px;
  height: 18px;
  border: 2px solid var(--text-muted);
  border-radius: 50%;
  position: relative;
  transition: all 0.2s;
}

.radio-label input:checked + .radio-custom {
  border-color: var(--primary);
  background-color: var(--primary);
}

.radio-label input:checked + .radio-custom::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 8px;
  height: 8px;
  background-color: white;
  border-radius: 50%;
}

/* Input Group */
.input-group {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.input-group label {
  font-weight: 600;
  color: var(--text-muted);
}

.input-group textarea {
  width: 100%;
  background-color: var(--bg-body);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: var(--spacing-md);
  color: var(--text-main);
  font-family: "Monaco", "Consolas", monospace;
  font-size: 0.875rem;
  resize: vertical;
  min-height: 120px;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.input-group textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(59, 130, 246, 0.2);
}

/* Boards Container */
.boards-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-xl);
  width: 100%;
  overflow-x: auto;
  padding: var(--spacing-md);
}

.board-section {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-md);
  animation: fadeIn 0.5s ease-out;
}

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

.board-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-main);
  background-color: var(--bg-surface);
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: 9999px;
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

/* Arrow Animation */
.arrow-container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 60px;
}

.arrow-down {
  font-size: 2rem;
  color: var(--primary);
  animation: bounce 2s infinite;
  text-shadow: 0 0 10px rgba(59, 130, 246, 0.5);
}

@keyframes bounce {
  0%,
  20%,
  50%,
  80%,
  100% {
    transform: translateY(0);
  }
  40% {
    transform: translateY(-10px);
  }
  60% {
    transform: translateY(-5px);
  }
}

/* Board Grid */
.board {
  display: flex;
  flex-direction: row;
  align-items: flex-start;
  gap: 8px;
  padding: var(--spacing-md);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  position: relative;
}

.col {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.cell {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
  font-size: 1.25rem;
  border: 2px solid var(--cell-border);
  box-sizing: border-box;
  transition: all 0.2s;
  background: var(--cell-bg); /* Fallback */
  box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.2);
  position: relative;
  user-select: none;
  z-index: 9999;
}

.cell:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
  z-index: 5;
}

.cell.blink {
  animation: cellBlink 1.5s infinite;
  cursor: pointer;
  border-color: var(--warning);
  box-shadow: 0 0 15px rgba(245, 158, 11, 0.4);
}

.cell.blink-hidden {
  opacity: 0.2;
  animation: none;
  cursor: pointer;
  filter: grayscale(100%);
}

@keyframes cellBlink {
  0%,
  100% {
    opacity: 1;
    transform: scale(1);
    box-shadow: 0 0 5px rgba(245, 158, 11, 0.4);
  }
  50% {
    opacity: 0.8;
    transform: scale(1.05);
    box-shadow: 0 0 20px rgba(245, 158, 11, 0.8);
  }
}

.cell.empty {
  visibility: hidden;
}

/* Border Overlays */
.border-overlay {
  position: absolute;
  border: 2px solid var(--text-muted);
  border-radius: var(--radius-lg);
  pointer-events: none;
  z-index: 10;
  transition: all 0.3s;
}

.border-overlay-silver {
  border: 3px solid #929292;
  background: rgba(192, 192, 192, 0.15);
  box-shadow: 0 0 15px rgba(192, 192, 192, 0.4);
  background: #929292;
}

.border-overlay-gold {
  border: 3px solid #ffd700;
  background: rgba(255, 215, 0, 0.15);
  box-shadow: 0 0 15px rgba(255, 215, 0, 0.4);
  background: #ffd700;
}

/* Responsive */
@media (max-width: 768px) {
  .app-header h1 {
    font-size: 1.5rem;
  }

  .panel-body {
    padding: var(--spacing-md);
  }

  .cell {
    width: 40px;
    height: 40px;
    font-size: 1rem;
  }
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  bottom: 20px;
  right: 20px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  z-index: 1000;
}

.toast {
  background: var(--bg-surface);
  color: var(--text-main);
  padding: 12px 24px;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  border-left: 4px solid var(--primary);
  animation: slideIn 0.3s ease-out;
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 300px;
}

.toast.error {
  border-left-color: var(--danger);
}

.toast.success {
  border-left-color: var(--success);
}

@keyframes slideIn {
  from {
    transform: translateX(100%);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

@keyframes fadeOut {
  to {
    opacity: 0;
    transform: translateX(100%);
  }
}