:root {
  /* Colores principales */
  --primary-color: #6366f1;
  --primary-hover: #5855eb;
  --secondary-color: #f3f4f6;
  --accent-color: #10b981;
  --danger-color: #ef4444;
  --warning-color: #f59e0b;
  
  /* Colores de texto */
  --text-primary: #1f2937;
  --text-secondary: #6b7280;
  --text-muted: #9ca3af;
  
  /* Colores de fondo */
  --bg-primary: #ffffff;
  --bg-secondary: #f9fafb;
  --bg-tertiary: #f3f4f6;
  
  /* Bordes y sombras */
  --border-color: #e5e7eb;
  --border-radius: 12px;
  --border-radius-sm: 8px;
  --box-shadow: 0 1px 3px 0 rgba(0, 0, 0, 0.1), 0 1px 2px 0 rgba(0, 0, 0, 0.06);
  --box-shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
  
  /* Espaciado */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.3rem;
  --spacing-md: 0.8rem;
  --spacing-lg: 1.15rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Tipografía */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  
  /* Transiciones */
  --transition: all 0.2s ease-in-out;
  --transition-fast: all 0.15s ease-in-out;
}

/* Tema oscuro */
[data-theme="dark"] {
  --text-primary: #f9fafb;
  --text-secondary: #d1d5db;
  --text-muted: #9ca3af;
  
  --bg-primary: #1f2937;
  --bg-secondary: #111827;
  --bg-tertiary: #374151;
  
  --border-color: #374151;
  --secondary-color: #374151;
}

/* Reset y base */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-secondary);
  transition: var(--transition);
  overflow-x: hidden;
}

/* Utilidades */
.hidden {
  display: none !important;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Pantalla de carga */
.loading-screen {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: var(--bg-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity 0.5s ease-in-out;
}

.loading-content {
  text-align: center;
}

.loading-spinner {
  width: 50px;
  height: 50px;
  border: 3px solid var(--border-color);
  border-top: 3px solid var(--primary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin: 0 auto var(--spacing-md);
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* Pantalla de autenticación */
.auth-screen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-hover) 100%);
  padding: var(--spacing-lg);
}

.auth-container {
  background: var(--bg-primary);
  padding: var(--spacing-2xl);
  border-radius: var(--border-radius);
  box-shadow: var(--box-shadow-lg);
  width: 100%;
  max-width: 400px;
  animation: slideUp 0.5s ease-out;
}

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

.auth-header {
  text-align: center;
  margin-bottom: var(--spacing-xl);
}

.auth-header h1 {
  font-size: var(--font-size-3xl);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.auth-header p {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

.auth-tabs {
  display: flex;
  margin-bottom: var(--spacing-lg);
  border-bottom: 1px solid var(--border-color);
}

.auth-tab {
  flex: 1;
  padding: var(--spacing-md);
  background: none;
  border: none;
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: var(--transition);
}

.auth-tab.active {
  color: var(--primary-color);
  border-bottom-color: var(--primary-color);
}

.auth-tab:hover {
  color: var(--text-primary);
}

/* Formularios */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-group label {
  display: block;
  margin-bottom: var(--spacing-sm);
  font-weight: 500;
  color: var(--text-primary);
  font-size: var(--font-size-sm);
}

.form-group input {
  width: 100%;
  padding: var(--spacing-md);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-base);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: var(--transition);
}

.form-group input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

/* Botones */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-lg);
  border: none;
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-sm);
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition);
  min-height: 44px;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

.auth-form .btn-primary {
  width: 100%;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  transform: translateY(-1px);
}

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

.btn-ghost {
  background-color: transparent;
  color: var(--text-secondary);
  padding: var(--spacing-sm) var(--spacing-md);
}

.btn-ghost:hover {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
  transform: none !important;
}

.btn-social {
  background: white;
  color: #374151;
  border: 1px solid #d1d5db;
  width: 100%;
  font-weight: 500;
}

.btn-social:hover {
  background: #f9fafb;
  border-color: #9ca3af;
}

.btn-social svg {
  width: 18px;
  height: 18px;
}

/* Divisor de autenticación */
.divider-container {
  display: flex;
  align-items: center;
  margin: var(--spacing-lg) 0;
  color: var(--text-muted);
}

.divider-line {
  flex: 1;
  height: 1px;
  background-color: var(--border-color);
}

.divider-text {
  padding: 0 var(--spacing-md);
  font-size: var(--font-size-sm);
  font-weight: 500;
}

/* Animación de spinner */
@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Aplicación principal */
.app {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.app-header {
  background-color: var(--bg-primary);
  border-bottom: 1px solid var(--border-color);
  padding: var(--spacing-lg);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.header-content h1 {
  font-size: var(--font-size-2xl);
  font-weight: 600;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.user-indicator {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background-color: var(--bg-tertiary);
  cursor: pointer;
}

.user-provider-icon {
  width: 20px;
  height: 20px;
  background-size: contain;
  background-repeat: no-repeat;
  background-position: center;
}

.user-provider-icon.google {
  background-image: url('data:image/png;base64,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');
}

.user-provider-icon.email {
  background-image: url('data:image/svg+xml;base64,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');
  color: var(--text-primary);
}

.user-indicator:hover .user-tooltip {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.user-tooltip {
  position: absolute;
  top: calc(100% + 8px);
  right: 0;
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
  padding: var(--spacing-sm) var(--spacing-md);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-sm);
  white-space: nowrap;
  box-shadow: var(--box-shadow);
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  transform: translateY(5px);
  z-index: 110;
}

/* Contenido principal */
.main-content {
  flex: 1;
  max-width: 800px;
  margin: 0 auto;
  padding: var(--spacing-xl) var(--spacing-lg);
  width: 100%;
}

/* Sección agregar tarea */
.add-task-section {
  margin-bottom: var(--spacing-xl);
}

.task-input-group {
  display: flex;
  gap: var(--spacing-md);
}

.task-input-group input {
  flex: 1;
  padding: var(--spacing-md) var(--spacing-lg);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-base);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  transition: var(--transition);
}

.task-input-group input:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

.btn-icon {
  font-size: var(--font-size-lg);
  font-weight: bold;
}

/* Filtros */
.filters-section {
  margin-bottom: var(--spacing-xl);
}

.filters {
  display: flex;
  gap: var(--spacing-sm);
  justify-content: center;
}

.filter-btn {
  padding: var(--spacing-sm) var(--spacing-lg);
  border: 1px solid var(--border-color);
  background-color: var(--bg-primary);
  color: var(--text-secondary);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-sm);
  cursor: pointer;
  transition: var(--transition);
}

.filter-btn.active {
  background-color: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
}

.filter-btn:hover:not(.active) {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
}

/* Lista de tareas */
.tasks-container {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.task-item {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  padding: var(--spacing-lg);
  transition: var(--transition);
  animation: slideInFromRight 0.3s ease-out;
}

@keyframes slideInFromRight {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.task-item:hover {
  transform: translateY(-2px);
  box-shadow: var(--box-shadow-lg);
}

.task-item.completed {
  opacity: 0.7;
}

.task-content {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
}

.task-checkbox {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border-color);
  border-radius: 4px;
  cursor: pointer;
  position: relative;
  transition: var(--transition);
}

.task-checkbox.checked {
  background-color: var(--accent-color);
  border-color: var(--accent-color);
}

.task-checkbox.checked::after {
  content: '✓';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: white;
  font-size: var(--font-size-xs);
  font-weight: bold;
}

.task-text {
  flex: 1;
  font-size: var(--font-size-base);
  color: var(--text-primary);
  transition: var(--transition);
}

.task-item.completed .task-text {
  text-decoration: line-through;
  color: var(--text-muted);
}

.task-actions {
  display: flex;
  gap: var(--spacing-sm);
}

.btn-delete {
  padding: var(--spacing-sm);
  background-color: transparent;
  color: var(--danger-color);
  border: 1px solid var(--danger-color);
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  font-size: var(--font-size-sm);
  transition: var(--transition);
  min-width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.btn-delete:hover {
  background-color: var(--danger-color);
  color: white;
}

/* Estado vacío */
.empty-state {
  text-align: center;
  padding: var(--spacing-2xl);
  color: var(--text-secondary);
}

.empty-icon {
  font-size: 4rem;
  margin-bottom: var(--spacing-lg);
}

.empty-state h3 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

/* Toast notifications */
.toast-container {
  position: fixed;
  top: var(--spacing-lg);
  right: var(--spacing-lg);
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

.toast {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius-sm);
  padding: var(--spacing-md) var(--spacing-lg);
  box-shadow: var(--box-shadow-lg);
  min-width: 300px;
  animation: slideInFromTop 0.3s ease-out;
}

@keyframes slideInFromTop {
  from {
    opacity: 0;
    transform: translateY(-30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.toast.success {
  border-left: 4px solid var(--accent-color);
}

.toast.error {
  border-left: 4px solid var(--danger-color);
}

.toast.warning {
  border-left: 4px solid var(--warning-color);
}

/* Error messages */
.error-message {
  background-color: #fef2f2;
  border: 1px solid #fecaca;
  color: #dc2626;
  padding: var(--spacing-md);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-sm);
  margin-top: var(--spacing-md);
}

[data-theme="dark"] .error-message {
  background-color: #450a0a;
  border-color: #dc2626;
  color: #fca5a5;
}

/* Responsive */
@media (max-width: 768px) {
  .auth-container {
    padding: var(--spacing-lg);
  }
  
  .header-content {
    padding: 0;
  }
  
  .header-content h1 {
    font-size: var(--font-size-xl);
  }
  
  .main-content {
    padding: var(--spacing-lg);
  }
  
  .task-input-group {
    flex-direction: column;
  }
  
  .filters {
    flex-wrap: wrap;
  }
  
  .task-content {
    /* Mantener alineación centrada en móvil para evitar desajustes verticales */
    align-items: center;
    gap: var(--spacing-sm);
  }
  
  .task-actions {
    /* Evitar que el botón suba y se desalineé con el texto/checkbox */
    margin-top: 0;
  }
  
  .toast-container {
    top: var(--spacing-sm);
    right: var(--spacing-sm);
    left: var(--spacing-sm);
  }
  
  .toast {
    min-width: auto;
  }
}

@media (max-width: 480px) {
  .auth-container {
    margin: var(--spacing-sm);
  }
  
  .header-actions {
    gap: var(--spacing-xs);
  }
  
  .btn {
    padding: var(--spacing-sm) var(--spacing-md);
    font-size: var(--font-size-xs);
  }
  
  .empty-icon {
    font-size: 3rem;
  }
}

/* Animaciones de entrada */
.fade-in {
  animation: fadeIn 0.5s ease-out;
}

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

/* Focus visible para accesibilidad */
.btn:focus-visible,
.task-checkbox:focus-visible,
input:focus-visible {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}