:root {
  /* Primary Colors */
  --primary-50: #eff6ff;
  --primary-100: #dbeafe;
  --primary-200: #bfdbfe;
  --primary-300: #93c5fd;
  --primary-400: #60a5fa;
  --primary-500: #3b82f6;
  --primary-600: #2563eb;
  --primary-700: #1d4ed8;
  --primary-800: #1e40af;
  --primary-900: #1e3a8a;

  /* Secondary Colors */
  --secondary-50: #f0fdfa;
  --secondary-100: #ccfbf1;
  --secondary-200: #99f6e4;
  --secondary-300: #5eead4;
  --secondary-400: #2dd4bf;
  --secondary-500: #14b8a6;
  --secondary-600: #0d9488;
  --secondary-700: #0f766e;
  --secondary-800: #115e59;
  --secondary-900: #134e4a;

  /* Accent Colors */
  --accent-50: #fff7ed;
  --accent-100: #ffedd5;
  --accent-200: #fed7aa;
  --accent-300: #fdba74;
  --accent-400: #fb923c;
  --accent-500: #f97316;
  --accent-600: #ea580c;
  --accent-700: #c2410c;
  --accent-800: #9a3412;
  --accent-900: #7c2d12;

  /* Status Colors */
  --success-50: #f0fdf4;
  --success-500: #22c55e;
  --success-600: #16a34a;
  
  --warning-50: #fffbeb;
  --warning-500: #f59e0b;
  --warning-600: #d97706;
  
  --error-50: #fef2f2;
  --error-500: #ef4444;
  --error-600: #dc2626;
  
  --info-50: #f0f9ff;
  --info-500: #06b6d4;
  --info-600: #0891b2;

  /* Neutral Colors - Light Theme */
  --neutral-0: #ffffff;
  --neutral-50: #f9fafb;
  --neutral-100: #f3f4f6;
  --neutral-200: #e5e7eb;
  --neutral-300: #d1d5db;
  --neutral-400: #9ca3af;
  --neutral-500: #6b7280;
  --neutral-600: #4b5563;
  --neutral-700: #374151;
  --neutral-800: #1f2937;
  --neutral-900: #111827;

  /* Typography */
  --font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-weight-light: 300;
  --font-weight-normal: 400;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;

  /* Spacing */
  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;
  --space-2xl: 3rem;
  --space-3xl: 4rem;

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-2xl: 1.5rem;

  /* 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);
  --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);

  /* Transitions */
  --transition-fast: 0.15s ease;
  --transition-base: 0.2s ease;
  --transition-slow: 0.3s ease;
}

/* Dark Theme Variables */
[data-theme="dark"] {
  --neutral-0: #0f1419;
  --neutral-50: #1a202c;
  --neutral-100: #2d3748;
  --neutral-200: #4a5568;
  --neutral-300: #718096;
  --neutral-400: #a0aec0;
  --neutral-500: #cbd5e0;
  --neutral-600: #e2e8f0;
  --neutral-700: #edf2f7;
  --neutral-800: #f7fafc;
  --neutral-900: #ffffff;
}

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

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

body {
  font-family: var(--font-family);
  font-weight: var(--font-weight-normal);
  line-height: 1.5;
  color: var(--neutral-800);
  background-color: var(--neutral-0);
  transition: background-color var(--transition-base), color var(--transition-base);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: var(--font-weight-semibold);
  line-height: 1.2;
  color: var(--neutral-900);
  margin-bottom: var(--space-md);
}

h1 { font-size: 2.25rem; }
h2 { font-size: 1.875rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }
h5 { font-size: 1.125rem; }
h6 { font-size: 1rem; }

p {
  margin-bottom: var(--space-md);
  color: var(--neutral-700);
}

a {
  color: var(--primary-600);
  text-decoration: none;
  transition: color var(--transition-fast);
}

a:hover {
  color: var(--primary-700);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  font-size: 0.875rem;
  font-weight: var(--font-weight-medium);
  text-align: center;
  text-decoration: none;
  border: 1px solid transparent;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  user-select: none;
  position: relative;
  overflow: hidden;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background-color: var(--primary-500);
  color: white;
  border-color: var(--primary-500);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--primary-600);
  border-color: var(--primary-600);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary {
  background-color: var(--secondary-500);
  color: white;
  border-color: var(--secondary-500);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--secondary-600);
  border-color: var(--secondary-600);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-outline {
  background-color: transparent;
  color: var(--primary-600);
  border-color: var(--primary-300);
}

.btn-outline:hover:not(:disabled) {
  background-color: var(--primary-50);
  border-color: var(--primary-400);
}

.btn-ghost {
  background-color: transparent;
  color: var(--neutral-600);
  border-color: transparent;
}

.btn-ghost:hover:not(:disabled) {
  background-color: var(--neutral-100);
  color: var(--neutral-800);
}

.btn-sm {
  padding: var(--space-xs) var(--space-md);
  font-size: 0.8125rem;
}

.btn-lg {
  padding: var(--space-md) var(--space-2xl);
  font-size: 1rem;
}

.btn-full {
  width: 100%;
  justify-content: center;
}

.btn-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0;
  border: none;
  border-radius: var(--radius-md);
  background-color: transparent;
  color: var(--neutral-500);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-icon:hover {
  background-color: var(--neutral-100);
  color: var(--neutral-700);
}

/* Form Elements */
.form-group {
  margin-bottom: var(--space-lg);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--space-lg);
}

label {
  display: block;
  font-size: 0.875rem;
  font-weight: var(--font-weight-medium);
  color: var(--neutral-700);
  margin-bottom: var(--space-xs);
}

input, select, textarea {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  font-size: 0.875rem;
  border: 1px solid var(--neutral-300);
  border-radius: var(--radius-md);
  background-color: var(--neutral-0);
  color: var(--neutral-800);
  transition: all var(--transition-fast);
}

input:focus, select:focus, textarea:focus {
  outline: none;
  border-color: var(--primary-500);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

input::placeholder, textarea::placeholder {
  color: var(--neutral-400);
}

/* Status Badges */
.status-badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.75rem;
  font-weight: var(--font-weight-medium);
  border-radius: var(--radius-sm);
  text-transform: uppercase;
  letter-spacing: 0.025em;
}

.status-success {
  background-color: var(--success-50);
  color: var(--success-600);
}

.status-warning {
  background-color: var(--warning-50);
  color: var(--warning-600);
}

.status-danger {
  background-color: var(--error-50);
  color: var(--error-600);
}

.status-info {
  background-color: var(--info-50);
  color: var(--info-600);
}

.status-secondary {
  background-color: var(--neutral-100);
  color: var(--neutral-600);
}

/* Priority Badges */
.priority-badge {
  display: inline-flex;
  align-items: center;
  padding: var(--space-xs) var(--space-sm);
  font-size: 0.75rem;
  font-weight: var(--font-weight-medium);
  border-radius: var(--radius-sm);
  text-transform: uppercase;
  letter-spacing: 0.025em;
}

.priority-low {
  background-color: var(--neutral-100);
  color: var(--neutral-600);
}

.priority-medium {
  background-color: var(--warning-50);
  color: var(--warning-600);
}

.priority-high {
  background-color: var(--accent-50);
  color: var(--accent-600);
}

.priority-critical {
  background-color: var(--error-50);
  color: var(--error-600);
}

/* Checkbox Styles */
.checkbox {
  display: flex;
  align-items: center;
  cursor: pointer;
  font-size: 0.875rem;
  color: var(--neutral-700);
  user-select: none;
}

.checkbox input {
  position: absolute;
  opacity: 0;
  cursor: pointer;
  height: 0;
  width: 0;
}

.checkmark {
  height: 1.25rem;
  width: 1.25rem;
  background-color: var(--neutral-0);
  border: 2px solid var(--neutral-300);
  border-radius: var(--radius-sm);
  margin-right: var(--space-sm);
  position: relative;
  transition: all var(--transition-fast);
}

.checkbox:hover .checkmark {
  border-color: var(--primary-400);
}

.checkbox input:checked ~ .checkmark {
  background-color: var(--primary-500);
  border-color: var(--primary-500);
}

.checkmark:after {
  content: "";
  position: absolute;
  display: none;
  left: 4px;
  top: 1px;
  width: 4px;
  height: 8px;
  border: solid white;
  border-width: 0 2px 2px 0;
  transform: rotate(45deg);
}

.checkbox input:checked ~ .checkmark:after {
  display: block;
}

/* Loading States */
.btn-loader {
  width: 1rem;
  height: 1rem;
  border: 2px solid transparent;
  border-top: 2px solid currentColor;
  border-radius: 50%;
  animation: spin 1s linear infinite;
}

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

/* Utility Classes */
.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;
}

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

.text-right {
  text-align: right;
}

.font-medium {
  font-weight: var(--font-weight-medium);
}

.font-semibold {
  font-weight: var(--font-weight-semibold);
}

.font-bold {
  font-weight: var(--font-weight-bold);
}

/* Toast Notifications */
#toast-container {
  position: fixed;
  top: var(--space-lg);
  right: var(--space-lg);
  z-index: 1000;
  max-width: 400px;
}

.toast {
  display: flex;
  align-items: center;
  padding: var(--space-md) var(--space-lg);
  margin-bottom: var(--space-sm);
  background-color: var(--neutral-0);
  border: 1px solid var(--neutral-200);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  animation: toast-slide-in 0.3s ease;
}

.toast.success {
  border-left: 4px solid var(--success-500);
}

.toast.error {
  border-left: 4px solid var(--error-500);
}

.toast.warning {
  border-left: 4px solid var(--warning-500);
}

.toast.info {
  border-left: 4px solid var(--info-500);
}

@keyframes toast-slide-in {
  from {
    transform: translateX(100%);
    opacity: 0;
  }
  to {
    transform: translateX(0);
    opacity: 1;
  }
}

/* Auth Page Styles */
.auth-page {
  background: linear-gradient(135deg, var(--primary-50) 0%, var(--secondary-50) 100%);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
}

.auth-container {
  width: 100%;
  max-width: 480px;
  position: relative;
}

.auth-card {
  background-color: var(--neutral-0);
  border-radius: var(--radius-2xl);
  padding: var(--space-3xl);
  box-shadow: var(--shadow-xl);
  border: 1px solid var(--neutral-200);
}

.auth-header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}

.logo {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
  margin-bottom: var(--space-lg);
}

.logo-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  animation: logo-float 3s ease-in-out infinite;
}

@keyframes logo-float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-5px); }
}

.logo h1 {
  font-size: 1.5rem;
  font-weight: var(--font-weight-bold);
  color: var(--neutral-900);
  margin: 0;
}

.auth-subtitle {
  color: var(--neutral-600);
  font-size: 0.875rem;
  margin: 0;
}

.auth-tabs {
  display: flex;
  background-color: var(--neutral-50);
  border-radius: var(--radius-md);
  padding: var(--space-xs);
  margin-bottom: var(--space-2xl);
}

.tab-btn {
  flex: 1;
  padding: var(--space-sm) var(--space-md);
  font-size: 0.875rem;
  font-weight: var(--font-weight-medium);
  color: var(--neutral-600);
  background: transparent;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.tab-btn.active {
  background-color: var(--neutral-0);
  color: var(--primary-600);
  box-shadow: var(--shadow-sm);
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.auth-form {
  display: flex;
  flex-direction: column;
}

.form-options {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-2xl);
}

.forgot-link, .link {
  font-size: 0.875rem;
  color: var(--primary-600);
  text-decoration: none;
}

.forgot-link:hover, .link:hover {
  color: var(--primary-700);
  text-decoration: underline;
}

.theme-toggle {
  position: absolute;
  top: var(--space-lg);
  right: var(--space-lg);
}

/* Responsive Design */
@media (max-width: 768px) {
  .auth-page {
    padding: var(--space-md);
  }
  
  .auth-card {
    padding: var(--space-2xl);
  }
  
  .form-row {
    grid-template-columns: 1fr;
  }
  
  .form-options {
    flex-direction: column;
    gap: var(--space-md);
    align-items: flex-start;
  }
  
  .auth-tabs {
    flex-direction: column;
  }
  
  .tab-btn {
    text-align: left;
  }
}

/* Dark theme adjustments for auth page */
[data-theme="dark"] .auth-page {
  background: linear-gradient(135deg, var(--neutral-100) 0%, var(--neutral-50) 100%);
}

[data-theme="dark"] .auth-card {
  background-color: var(--neutral-100);
  border-color: var(--neutral-200);
}

[data-theme="dark"] .auth-tabs {
  background-color: var(--neutral-50);
}

[data-theme="dark"] .tab-btn.active {
  background-color: var(--neutral-100);
}