:root {
  /* Primitive Color Tokens */
  --color-white: rgba(255, 255, 255, 1);
  --color-black: rgba(0, 0, 0, 1);
  --color-cream-50: rgba(252, 252, 249, 1);
  --color-cream-100: rgba(255, 255, 253, 1);
  --color-gray-200: rgba(245, 245, 245, 1);
  --color-gray-300: rgba(167, 169, 169, 1);
  --color-gray-400: rgba(119, 124, 124, 1);
  --color-slate-500: rgba(98, 108, 113, 1);
  --color-brown-600: rgba(94, 82, 64, 1);
  --color-charcoal-700: rgba(31, 33, 33, 1);
  --color-charcoal-800: rgba(38, 40, 40, 1);
  --color-slate-900: rgba(19, 52, 59, 1);
  --color-teal-300: rgba(50, 184, 198, 1);
  --color-teal-400: rgba(45, 166, 178, 1);
  --color-teal-500: rgba(33, 128, 141, 1);
  --color-teal-600: rgba(29, 116, 128, 1);
  --color-teal-700: rgba(26, 104, 115, 1);
  --color-teal-800: rgba(41, 150, 161, 1);
  --color-red-400: rgba(255, 84, 89, 1);
  --color-red-500: rgba(192, 21, 47, 1);
  --color-orange-400: rgba(230, 129, 97, 1);
  --color-orange-500: rgba(168, 75, 47, 1);

  /* Semantic Color Tokens */
  --color-background: var(--color-cream-50);
  --color-surface: var(--color-cream-100);
  --color-text: var(--color-charcoal-800);
  --color-text-secondary: var(--color-slate-500);
  --color-primary: var(--color-teal-600);
  --color-primary-hover: var(--color-teal-700);
  --color-success: var(--color-teal-500);
  --color-error: var(--color-red-500);
  --color-warning: var(--color-orange-500);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu', 'Cantarell', sans-serif;
  background-color: var(--color-background);
  color: var(--color-text);
  line-height: 1.6;
}

/* Login Styles */
.login-container {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 2rem;
  background: linear-gradient(135deg, var(--color-teal-500) 0%, var(--color-teal-700) 100%);
}

.login-form {
  background: var(--color-surface);
  padding: 3rem;
  border-radius: 16px;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
  width: 100%;
  max-width: 400px;
}

.login-title {
  text-align: center;
  margin-bottom: 2rem;
  color: var(--color-primary);
  font-size: 1.75rem;
  font-weight: 600;
}

.form-group {
  margin-bottom: 1.5rem;
}

.form-label {
  display: block;
  margin-bottom: 0.5rem;
  font-weight: 500;
  color: var(--color-text);
}

.form-input {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 2px solid var(--color-gray-200);
  border-radius: 8px;
  font-size: 1rem;
  transition: border-color 0.3s ease;
}

.form-input:focus {
  outline: none;
  border-color: var(--color-primary);
}

.btn {
  padding: 0.75rem 1.5rem;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
}

.btn-primary {
  background: var(--color-primary);
  color: var(--color-white);
  width: 100%;
}

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

.btn-secondary {
  background: var(--color-gray-200);
  color: var(--color-text);
}

.btn-secondary:hover {
  background: var(--color-gray-300);
}

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

.btn-success:hover {
  background: var(--color-teal-700);
}

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

.btn-danger:hover {
  background: var(--color-red-400);
}

.btn-small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

/* Dashboard Styles */
.dashboard-container {
  min-height: 100vh;
  background: var(--color-background);
}

.dashboard-header {
  background: var(--color-surface);
  padding: 1rem 2rem;
  border-bottom: 1px solid var(--color-gray-200);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.dashboard-title {
  color: var(--color-primary);
  font-size: 1.5rem;
  font-weight: 600;
}

.user-info {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.user-email {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
}

.dashboard-content {
  padding: 2rem;
  max-width: 1200px;
  margin: 0 auto;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.stat-card {
  background: var(--color-surface);
  padding: 1.5rem;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.stat-label {
  color: var(--color-text-secondary);
  font-size: 0.875rem;
  margin-bottom: 0.5rem;
}

.stat-value {
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--color-text);
}

.stat-value.positive {
  color: var(--color-success);
}

.stat-value.negative {
  color: var(--color-error);
}

/* All Members Summary */
.all-members-summary {
  margin-bottom: 2rem;
}

.all-members-summary h3 {
  margin-bottom: 1.5rem;
  color: var(--color-text);
  font-size: 1.25rem;
  font-weight: 600;
}

.members-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
}

.member-card {
  background: linear-gradient(135deg, #ffffff 0%, #f8fafc 100%);
  padding: 1.5rem;
  border-radius: 12px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.08);
  border: 1px solid rgba(255, 255, 255, 0.8);
  transition: all 0.3s ease;
}

.member-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.member-card h4 {
  color: var(--color-text);
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 1rem;
  text-align: center;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--color-gray-200);
}

.member-card p {
  margin: 0.5rem 0;
  font-size: 0.875rem;
  font-weight: 500;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.member-card p.positive {
  color: var(--color-success);
  font-weight: 700;
}

.member-card p.negative {
  color: var(--color-error);
  font-weight: 700;
}

/* Navigation */
.nav-tabs {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.nav-tab {
  padding: 0.75rem 1.5rem;
  background: var(--color-surface);
  border: 2px solid var(--color-gray-200);
  border-radius: 8px;
  cursor: pointer;
  transition: all 0.3s ease;
  font-weight: 500;
  color: var(--color-text);
}

.nav-tab:hover {
  border-color: var(--color-primary);
  background: var(--color-primary);
  color: var(--color-white);
}

.nav-tab.active {
  background: var(--color-primary);
  border-color: var(--color-primary);
  color: var(--color-white);
}

/* Content Sections */
.content-section {
  background: var(--color-surface);
  padding: 2rem;
  border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}

.section-title {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
  color: var(--color-text);
}

/* Forms */
.expense-form {
  display: grid;
  gap: 1.5rem;
  max-width: 500px;
}

/* Tables */
.data-table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1rem;
  background: var(--color-surface);
  border-radius: 8px;
  overflow: hidden;
}

.data-table th,
.data-table td {
  padding: 1rem;
  text-align: left;
  border-bottom: 1px solid var(--color-gray-200);
}

.data-table th {
  background: var(--color-gray-200);
  font-weight: 600;
  color: var(--color-text);
}

.data-table tbody tr:hover {
  background: rgba(33, 128, 141, 0.05);
}

/* Settlement Styles */
.settlements-grid {
  display: grid;
  gap: 1rem;
  margin-top: 1rem;
}

.settlement-item {
  background: var(--color-surface);
  padding: 1.5rem;
  border-radius: 8px;
  border: 2px solid var(--color-gray-200);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.settlement-info {
  flex: 1;
}

.settlement-amount {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.25rem;
}

.settlement-description {
  color: var(--color-text-secondary);
  font-size: 0.9rem;
}

.settlement-actions {
  display: flex;
  gap: 0.5rem;
}

/* Payment Styles */
.payment-item {
  background: var(--color-surface);
  padding: 1.5rem;
  border-radius: 8px;
  border: 2px solid var(--color-gray-200);
  margin-bottom: 1rem;
}

.payment-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.5rem;
}

.payment-status {
  padding: 0.25rem 0.75rem;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
}

.payment-status.pending {
  background: var(--color-orange-400);
  color: var(--color-white);
}

.payment-status.confirmed {
  background: var(--color-success);
  color: var(--color-white);
}

/* Month Selector */
.month-selector {
  margin-bottom: 1.5rem;
}

.month-selector select {
  padding: 0.5rem 1rem;
  border: 2px solid var(--color-gray-200);
  border-radius: 8px;
  font-size: 1rem;
  background: var(--color-surface);
  color: var(--color-text);
}

/* Messages */
.error-message {
  background: rgba(255, 84, 89, 0.1);
  color: var(--color-error);
  padding: 1rem;
  border-radius: 8px;
  margin-bottom: 1rem;
  border: 1px solid rgba(255, 84, 89, 0.3);
}

.success-message {
  background: rgba(33, 128, 141, 0.1);
  color: var(--color-success);
  padding: 1rem;
  border-radius: 8px;
  margin-bottom: 1rem;
  border: 1px solid rgba(33, 128, 141, 0.3);
}

.info-message {
  background: rgba(168, 75, 47, 0.1);
  color: var(--color-warning);
  padding: 1rem;
  border-radius: 8px;
  margin-bottom: 1rem;
  border: 1px solid rgba(168, 75, 47, 0.3);
}

/* Loading States */
.loading {
  text-align: center;
  padding: 2rem;
  color: var(--color-text-secondary);
}

/* Responsive Design */
@media (max-width: 768px) {
  .dashboard-header {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }

  .nav-tabs {
    justify-content: center;
  }

  .stats-grid {
    grid-template-columns: 1fr;
  }

  .members-grid {
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 0.75rem;
  }

  .settlement-item {
    flex-direction: column;
    gap: 1rem;
    text-align: center;
  }

  .data-table {
    font-size: 0.875rem;
  }

  .data-table th,
  .data-table td {
    padding: 0.75rem 0.5rem;
  }

  .member-card {
    padding: 1rem;
  }

  .member-card h4 {
    font-size: 0.875rem;
  }

  .member-card p {
    font-size: 0.8rem;
  }
}