/* ===== CSS Variables & Design Tokens ===== */
:root {
  --bg-base: #070b14;
  --bg-primary: #0b1022;
  --bg-secondary: #111827;
  --bg-tertiary: #1a2035;
  --bg-elevated: #1e2742;
  --bg-hover: #243050;

  --border: #1e293b;
  --border-light: #2a3a55;
  --border-focus: #4a9eff;

  --text-primary: #e8ecf4;
  --text-secondary: #8899b4;
  --text-muted: #5a6a84;

  --accent-blue: #4a9eff;
  --accent-cyan: #22d3ee;
  --accent-purple: #a78bfa;
  --accent-green: #34d399;
  --accent-amber: #fbbf24;
  --accent-red: #f87171;
  --accent-pink: #f472b6;

  --gradient-primary: linear-gradient(135deg, #4a9eff 0%, #818cf8 100%);
  --gradient-accent: linear-gradient(135deg, #22d3ee 0%, #4a9eff 100%);
  --gradient-success: linear-gradient(135deg, #34d399 0%, #22d3ee 100%);
  --gradient-danger: linear-gradient(135deg, #f87171 0%, #fb923c 100%);

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.4);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.5);
  --shadow-lg: 0 8px 30px rgba(0,0,0,0.6);
  --shadow-glow-cyan: 0 0 20px rgba(34, 211, 238, 0.3);
  --shadow-glow-blue: 0 0 20px rgba(74, 158, 255, 0.3);

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-xl: 20px;

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  --sidebar-width: 260px;
  --header-height: 56px;
  --sim-bar-height: 64px;

  --transition-fast: 0.15s ease;
  --transition-base: 0.25s ease;
  --transition-slow: 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

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

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-base);
  color: var(--text-primary);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  background: var(--bg-base);
}

/* ===== Header ===== */
.header {
  height: var(--header-height);
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 20px;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  flex-shrink: 0;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo {
  display: flex;
  align-items: center;
  animation: logoSpin 20s linear infinite;
}

@keyframes logoSpin {
  from { transform: rotate(0deg); }
  to { transform: rotate(360deg); }
}

.header h1 {
  font-size: 1.1rem;
  font-weight: 700;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.02em;
}

.header-center {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

.mode-toggle {
  display: flex;
  position: relative;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px;
}

.mode-btn {
  position: relative;
  z-index: 2;
  padding: 6px 24px;
  border: none;
  background: none;
  color: var(--text-secondary);
  font-family: var(--font-mono);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: color var(--transition-fast);
  border-radius: 999px;
}

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

.mode-slider {
  position: absolute;
  top: 3px;
  left: 3px;
  width: calc(50% - 3px);
  height: calc(100% - 6px);
  background: var(--gradient-primary);
  border-radius: 999px;
  transition: transform var(--transition-slow);
  z-index: 1;
}

.mode-toggle:has(.mode-btn:last-child.active) .mode-slider {
  transform: translateX(100%);
}

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

.icon-btn {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  color: var(--text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.icon-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
  border-color: var(--border-light);
}

/* ===== Main Layout ===== */
.main-layout {
  display: flex;
  flex: 1;
  overflow: hidden;
}

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-primary);
  border-right: 1px solid var(--border);
  overflow-y: auto;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  flex-shrink: 0;
}

.sidebar::-webkit-scrollbar {
  width: 4px;
}

.sidebar::-webkit-scrollbar-track {
  background: transparent;
}

.sidebar::-webkit-scrollbar-thumb {
  background: var(--border-light);
  border-radius: 2px;
}

.panel {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 14px;
}

.panel-title {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.panel-title svg {
  opacity: 0.6;
}

/* Tool Grid */
.tool-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6px;
}

.tool-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 10px 6px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  font-family: var(--font-sans);
  font-size: 0.7rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.tool-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
  border-color: var(--border-light);
}

.tool-btn.active {
  background: rgba(74, 158, 255, 0.12);
  border-color: var(--accent-blue);
  color: var(--accent-blue);
  box-shadow: 0 0 12px rgba(74, 158, 255, 0.1);
}

/* Input Fields */
.input-field {
  width: 100%;
  padding: 8px 12px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 0.85rem;
  outline: none;
  transition: all var(--transition-fast);
}

.input-field.mono {
  font-family: var(--font-mono);
}

.input-field:focus {
  border-color: var(--accent-blue);
  box-shadow: 0 0 0 3px rgba(74, 158, 255, 0.1);
}

.input-field::placeholder {
  color: var(--text-muted);
}

select.input-field {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg width='12' height='8' viewBox='0 0 12 8' fill='none' xmlns='http://www.w3.org/2000/svg'%3E%3Cpath d='M1 1.5L6 6.5L11 1.5' stroke='%238899b4' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 10px center;
  padding-right: 30px;
}

/* Property Groups */
.property-group {
  margin-bottom: 10px;
}

.property-group:last-child {
  margin-bottom: 0;
}

.property-group > label {
  display: block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  margin-bottom: 6px;
}

/* Toggle Switch */
.toggle-label {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
  font-size: 0.85rem;
  color: var(--text-primary);
  user-select: none;
}

.toggle-label input[type="checkbox"] {
  display: none;
}

.toggle-switch {
  width: 36px;
  height: 20px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: 99px;
  position: relative;
  transition: all var(--transition-base);
  flex-shrink: 0;
}

.toggle-switch::after {
  content: '';
  position: absolute;
  width: 14px;
  height: 14px;
  background: var(--text-secondary);
  border-radius: 50%;
  top: 2px;
  left: 2px;
  transition: all var(--transition-base);
}

.toggle-label input:checked + .toggle-switch {
  background: var(--accent-blue);
  border-color: var(--accent-blue);
}

.toggle-label input:checked + .toggle-switch::after {
  transform: translateX(16px);
  background: white;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 16px;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.82rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: 0 2px 8px rgba(74, 158, 255, 0.25);
}

.btn-primary:hover {
  box-shadow: 0 4px 16px rgba(74, 158, 255, 0.4);
  transform: translateY(-1px);
}

.btn-accent {
  background: var(--gradient-accent);
  color: white;
  box-shadow: 0 2px 8px rgba(34, 211, 238, 0.2);
}

.btn-accent:hover {
  box-shadow: 0 4px 16px rgba(34, 211, 238, 0.35);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
  border-color: var(--border-light);
}

.btn:active {
  transform: translateY(0);
}

/* ===== Canvas Area ===== */
.canvas-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.canvas-container {
  flex: 1;
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(ellipse at center, rgba(74, 158, 255, 0.03) 0%, transparent 70%),
    var(--bg-base);
}

#automaton-canvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: default;
}

.canvas-hint {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  color: var(--text-muted);
  font-size: 0.9rem;
  pointer-events: none;
  text-align: center;
}

.canvas-hint p {
  max-width: 250px;
  line-height: 1.6;
}

/* Grid pattern drawn on canvas via JS — this is a subtle fallback */
.canvas-container::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 1px 1px, rgba(74, 158, 255, 0.06) 1px, transparent 0);
  background-size: 30px 30px;
  pointer-events: none;
  z-index: 0;
}

/* ===== Simulation Bar ===== */
.sim-bar {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 10px 20px;
  background: var(--bg-primary);
  border-top: 1px solid var(--border);
  flex-shrink: 0;
}

.sim-input-group {
  display: flex;
  align-items: center;
  gap: 10px;
}

.sim-input-group label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-secondary);
  white-space: nowrap;
}

.sim-input-wrapper {
  position: relative;
  width: 220px;
}

.sim-input-wrapper .input-field {
  padding-right: 36px;
}

.input-sigma {
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-muted);
  pointer-events: none;
}

.sim-buttons {
  display: flex;
  gap: 6px;
}

.sim-status {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 16px;
}

.sim-step,
.sim-current {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text-secondary);
  padding: 4px 10px;
  background: var(--bg-secondary);
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  min-width: 60px;
  text-align: center;
}

.sim-step:empty, .sim-current:empty {
  display: none;
}

/* Inline result styling in sim bar */
.sim-result-accepted {
  background: rgba(52, 211, 153, 0.15) !important;
  border-color: var(--accent-green) !important;
  color: var(--accent-green) !important;
  font-weight: 700;
  animation: resultPulse 0.5s ease;
  box-shadow: 0 0 12px rgba(52, 211, 153, 0.25);
}

.sim-result-rejected {
  background: rgba(248, 113, 113, 0.15) !important;
  border-color: var(--accent-red) !important;
  color: var(--accent-red) !important;
  font-weight: 700;
  animation: resultPulse 0.5s ease;
  box-shadow: 0 0 12px rgba(248, 113, 113, 0.25);
}

@keyframes resultPulse {
  0% { transform: scale(0.95); opacity: 0; }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); opacity: 1; }
}

/* ===== Result Overlay ===== */
.result-overlay {
  position: fixed;
  inset: 0;
  background: rgba(7, 11, 20, 0.7);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  animation: fadeIn 0.3s ease;
}

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

.result-card {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 40px 50px;
  text-align: center;
  box-shadow: var(--shadow-lg);
  animation: slideUp 0.4s cubic-bezier(0.16, 1, 0.3, 1);
  min-width: 340px;
}

@keyframes slideUp {
  from { transform: translateY(30px) scale(0.95); opacity: 0; }
  to { transform: translateY(0) scale(1); opacity: 1; }
}

.result-icon {
  width: 80px;
  height: 80px;
  margin: 0 auto 20px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2.5rem;
}

.result-icon.accepted {
  background: rgba(52, 211, 153, 0.15);
  border: 2px solid var(--accent-green);
  box-shadow: 0 0 30px rgba(52, 211, 153, 0.2);
}

.result-icon.rejected {
  background: rgba(248, 113, 113, 0.15);
  border: 2px solid var(--accent-red);
  box-shadow: 0 0 30px rgba(248, 113, 113, 0.2);
}

.result-text {
  font-size: 1.5rem;
  font-weight: 800;
  margin-bottom: 8px;
  letter-spacing: 0.03em;
}

.result-text.accepted {
  color: var(--accent-green);
}

.result-text.rejected {
  color: var(--accent-red);
}

.result-details {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 24px;
  font-family: var(--font-mono);
}

/* ===== Modals ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(7, 11, 20, 0.7);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  animation: fadeIn 0.2s ease;
}

.modal {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  width: 90%;
  max-width: 500px;
  box-shadow: var(--shadow-lg);
  animation: slideUp 0.3s cubic-bezier(0.16, 1, 0.3, 1);
}

.modal-sm {
  max-width: 380px;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px 0;
}

.modal-header h2 {
  font-size: 1.1rem;
  font-weight: 700;
}

.modal-close {
  width: 32px;
  height: 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  background: var(--bg-tertiary);
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  font-size: 1.2rem;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.modal-close:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.modal-body {
  padding: 20px 24px;
}

.modal-footer {
  padding: 0 24px 20px;
  display: flex;
  justify-content: flex-end;
  gap: 8px;
}

.transition-info {
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 16px;
  padding: 10px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-sm);
  font-family: var(--font-mono);
  text-align: center;
}

/* Help Modal */
.help-section {
  margin-bottom: 16px;
}

.help-section h4 {
  font-size: 0.95rem;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--text-primary);
}

.help-section p {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

kbd {
  display: inline-block;
  padding: 2px 8px;
  background: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--text-primary);
}

.shortcuts-table {
  width: 100%;
  border-collapse: collapse;
}

.shortcuts-table td {
  padding: 6px 8px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  border-bottom: 1px solid var(--border);
}

.shortcuts-table td:first-child {
  width: 80px;
}

/* ===== Toasts ===== */
.toast-container {
  position: fixed;
  bottom: 80px;
  right: 20px;
  display: flex;
  flex-direction: column-reverse;
  gap: 8px;
  z-index: 2000;
  pointer-events: none;
}

.toast {
  padding: 10px 18px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  font-size: 0.85rem;
  color: var(--text-primary);
  box-shadow: var(--shadow-md);
  animation: toastIn 0.3s ease, toastOut 0.3s ease 2.5s forwards;
  pointer-events: auto;
  display: flex;
  align-items: center;
  gap: 8px;
}

.toast.error {
  border-color: var(--accent-red);
  background: rgba(248, 113, 113, 0.1);
}

.toast.success {
  border-color: var(--accent-green);
  background: rgba(52, 211, 153, 0.1);
}

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

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

/* ===== Canvas cursor states ===== */
.canvas-container[data-tool="select"] #automaton-canvas { cursor: default; }
.canvas-container[data-tool="add-state"] #automaton-canvas { cursor: crosshair; }
.canvas-container[data-tool="add-transition"] #automaton-canvas { cursor: pointer; }
.canvas-container[data-tool="delete"] #automaton-canvas { cursor: not-allowed; }
.canvas-container.dragging #automaton-canvas { cursor: grabbing; }

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .sidebar {
    width: 220px;
  }
  .sim-input-wrapper {
    width: 160px;
  }
}

@media (max-width: 700px) {
  .sidebar {
    display: none;
  }
  .sim-bar {
    flex-wrap: wrap;
    padding: 8px 12px;
  }
  .header h1 {
    font-size: 0.9rem;
  }
}

/* ===== Pulse animation for active states in sim ===== */
@keyframes pulseGlow {
  0%, 100% { filter: drop-shadow(0 0 8px rgba(34, 211, 238, 0.5)); }
  50% { filter: drop-shadow(0 0 20px rgba(34, 211, 238, 0.9)); }
}