/* Invoice System - Modern CSS Styles */

/* ===== CSS Variables ===== */
:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --primary-light: #818cf8;
  --success: #10b981;
  --success-dark: #059669;
  --warning: #f59e0b;
  --warning-dark: #d97706;
  --danger: #ef4444;
  --danger-dark: #dc2626;
  --info: #3b82f6;

  /* Light Theme */
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f1f5f9;
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);

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

  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;

  /* Transitions */
  --transition: all 0.2s ease;
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f1f5f9;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --border: #334155;
  --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.4);
}

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

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  min-height: 100vh;
  transition: var(--transition);
}

/* ===== Typography ===== */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  color: var(--text-primary);
}

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

p {
  color: var(--text-secondary);
}

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

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

/* ===== Layout ===== */
.app-container {
  display: flex;
  min-height: 100vh;
}

/* Sidebar */
.sidebar {
  width: 280px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border);
  padding: var(--space-lg);
  position: fixed;
  height: 100vh;
  overflow-y: auto;
  transition: var(--transition);
  z-index: 100;
}

.sidebar-header {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding-bottom: var(--space-lg);
  border-bottom: 1px solid var(--border);
  margin-bottom: var(--space-lg);
}

.logo {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  color: white;
}

.brand-name {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
}

.nav-menu {
  list-style: none;
}

.nav-item {
  margin-bottom: var(--space-xs);
}

.nav-link {
  display: flex;
  align-items: center;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--radius-lg);
  color: var(--text-secondary);
  font-weight: 500;
  transition: var(--transition);
}

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

.nav-link.active {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
}

.nav-icon {
  font-size: 1.25rem;
  width: 24px;
  text-align: center;
}

.sidebar-footer {
  margin-top: auto;
  padding-top: var(--space-lg);
  border-top: 1px solid var(--border);
}

/* Main Content */
.main-content {
  flex: 1;
  margin-left: 280px;
  padding: var(--space-xl);
  min-height: 100vh;
}

/* Header */
.page-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-xl);
  flex-wrap: wrap;
  gap: var(--space-md);
}

.page-title {
  font-size: 1.75rem;
  font-weight: 700;
}

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

/* Theme Toggle */
.theme-toggle {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-lg);
  border: 2px solid var(--border);
  background: var(--bg-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  transition: var(--transition);
}

.theme-toggle:hover {
  transform: scale(1.1);
  border-color: var(--primary);
}

/* User Menu */
.user-menu {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.user-avatar {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-full);
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  font-weight: 600;
}

.user-info {
  display: flex;
  flex-direction: column;
}

.user-name {
  font-weight: 600;
  color: var(--text-primary);
}

.user-email {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* ===== Cards ===== */
.card {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow);
  padding: var(--space-xl);
  transition: var(--transition);
}

.card:hover {
  box-shadow: var(--shadow-lg);
}

.card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.card-title {
  font-size: 1.125rem;
  font-weight: 600;
}

.card-body {
  padding: 0;
}

/* Stats Cards */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-lg);
  margin-bottom: var(--space-xl);
}

.stat-card {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow);
  padding: var(--space-xl);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.stat-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--primary) 0%, var(--primary-light) 100%);
}

.stat-card.success::before {
  background: linear-gradient(90deg, var(--success) 0%, #34d399 100%);
}

.stat-card.warning::before {
  background: linear-gradient(90deg, var(--warning) 0%, #fbbf24 100%);
}

.stat-card.danger::before {
  background: linear-gradient(90deg, var(--danger) 0%, #f87171 100%);
}

.stat-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.stat-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: var(--space-md);
}

.stat-icon.primary {
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
}

.stat-icon.success {
  background: rgba(16, 185, 129, 0.1);
  color: var(--success);
}

.stat-icon.warning {
  background: rgba(245, 158, 11, 0.1);
  color: var(--warning);
}

.stat-icon.danger {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger);
}

.stat-value {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.stat-label {
  color: var(--text-muted);
  font-size: 0.875rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-lg);
  font-size: 0.9375rem;
  font-weight: 500;
  font-family: inherit;
  cursor: pointer;
  transition: var(--transition);
  border: none;
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(99, 102, 241, 0.4);
  color: white;
}

.btn-success {
  background: linear-gradient(135deg, var(--success) 0%, var(--success-dark) 100%);
  color: white;
}

.btn-warning {
  background: linear-gradient(135deg, var(--warning) 0%, var(--warning-dark) 100%);
  color: white;
}

.btn-danger {
  background: linear-gradient(135deg, var(--danger) 0%, var(--danger-dark) 100%);
  color: white;
}

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

.btn-secondary:hover {
  background: var(--border);
}

.btn-outline {
  background: transparent;
  border: 2px solid var(--border);
  color: var(--text-primary);
}

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

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

.btn-lg {
  padding: 1rem 2rem;
  font-size: 1rem;
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
}

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

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

.form-label.required::after {
  content: ' *';
  color: var(--danger);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: 0.75rem 1rem;
  border: 2px solid var(--border);
  border-radius: var(--radius-lg);
  font-size: 0.9375rem;
  font-family: inherit;
  background: var(--bg-secondary);
  color: var(--text-primary);
  transition: var(--transition);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 4px rgba(99, 102, 241, 0.1);
}

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

.form-textarea {
  min-height: 100px;
  resize: vertical;
}

.form-select {
  cursor: pointer;
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 12 12'%3E%3Cpath fill='%2394a3b8' d='M6 8L1 3h10z'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 1rem center;
  padding-right: 2.5rem;
}

.form-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--space-lg);
}

/* ===== Tables ===== */
.table-container {
  overflow-x: auto;
  border-radius: var(--radius-xl);
  border: 1px solid var(--border);
}

.table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9375rem;
}

.table th,
.table td {
  padding: var(--space-lg);
  text-align: left;
  border-bottom: 1px solid var(--border);
}

.table th {
  background: var(--bg-tertiary);
  font-weight: 600;
  color: var(--text-primary);
  text-transform: uppercase;
  font-size: 0.75rem;
  letter-spacing: 0.05em;
}

.table tr:hover {
  background: var(--bg-tertiary);
}

.table tr:last-child td {
  border-bottom: none;
}

/* Status Badges */
.badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-xs);
  padding: 0.375rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.badge-success {
  background: rgba(16, 185, 129, 0.1);
  color: var(--success);
}

.badge-warning {
  background: rgba(245, 158, 11, 0.1);
  color: var(--warning);
}

.badge-danger {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger);
}

.badge-primary {
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
}

.badge-secondary {
  background: rgba(148, 159, 191, 0.1);
  color: var(--text-muted);
}

/* ===== Action Buttons in Table ===== */
.table-actions {
  display: flex;
  gap: var(--space-sm);
}

.action-btn {
  width: 32px;
  height: 32px;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.875rem;
  transition: var(--transition);
}

.action-btn.edit {
  background: rgba(99, 102, 241, 0.1);
  color: var(--primary);
}

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

.action-btn.delete {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger);
}

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

.action-btn.view {
  background: rgba(16, 185, 129, 0.1);
  color: var(--success);
}

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

/* ===== Modal ===== */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
  opacity: 0;
  visibility: hidden;
  transition: var(--transition);
  padding: var(--space-lg);
}

.modal-overlay.active {
  opacity: 1;
  visibility: visible;
}

.modal {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  width: 100%;
  max-width: 500px;
  max-height: 90vh;
  overflow-y: auto;
  transform: scale(0.9);
  transition: var(--transition);
}

.modal-overlay.active .modal {
  transform: scale(1);
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--space-xl);
  border-bottom: 1px solid var(--border);
}

.modal-title {
  font-size: 1.25rem;
  font-weight: 600;
}

.modal-close {
  width: 32px;
  height: 32px;
  border: none;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 1.25rem;
  color: var(--text-secondary);
  transition: var(--transition);
}

.modal-close:hover {
  background: var(--danger);
  color: white;
}

.modal-body {
  padding: var(--space-xl);
}

.modal-footer {
  display: flex;
  gap: var(--space-md);
  padding: var(--space-xl);
  border-top: 1px solid var(--border);
  justify-content: flex-end;
}

/* ===== Login Page ===== */
.login-container {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, #667eea 0%, #764ba2 50%, #f093fb 100%);
  padding: var(--space-xl);
}

[data-theme="dark"] .login-container {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #312e81 100%);
}

.login-card {
  background: var(--bg-secondary);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-lg);
  padding: var(--space-2xl);
  width: 100%;
  max-width: 420px;
}

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

.login-logo {
  width: 64px;
  height: 64px;
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-light) 100%);
  border-radius: var(--radius-xl);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  color: white;
  margin: 0 auto var(--space-lg);
}

.login-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: var(--space-sm);
}

.login-subtitle {
  color: var(--text-muted);
}

/* ===== Invoice Items Table ===== */
.items-table {
  width: 100%;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}

.items-table th,
.items-table td {
  padding: var(--space-md);
  border-bottom: 1px solid var(--border);
}

.items-table th {
  background: var(--bg-tertiary);
  font-weight: 600;
  font-size: 0.8125rem;
  text-transform: uppercase;
}

.items-table input,
.items-table select {
  width: 100%;
  padding: 0.5rem;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.875rem;
}

.items-table .remove-btn {
  width: 28px;
  height: 28px;
  border: none;
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger);
  border-radius: var(--radius-md);
  cursor: pointer;
  font-size: 1rem;
  transition: var(--transition);
}

.items-table .remove-btn:hover {
  background: var(--danger);
  color: white;
}

.invoice-totals {
  margin-top: var(--space-lg);
  padding: var(--space-lg);
  background: var(--bg-tertiary);
  border-radius: var(--radius-lg);
}

.total-row {
  display: flex;
  justify-content: space-between;
  padding: var(--space-sm) 0;
  font-size: 0.9375rem;
}

.total-row.grand-total {
  border-top: 2px solid var(--border);
  padding-top: var(--space-md);
  font-size: 1.125rem;
  font-weight: 700;
  color: var(--primary);
}

/* ===== Empty State ===== */
.empty-state {
  text-align: center;
  padding: var(--space-2xl);
  color: var(--text-muted);
}

.empty-icon {
  font-size: 4rem;
  margin-bottom: var(--space-lg);
  opacity: 0.5;
}

.empty-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: var(--space-sm);
}

.empty-text {
  color: var(--text-muted);
  margin-bottom: var(--space-lg);
}

/* ===== Alerts ===== */
.alert {
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--radius-lg);
  margin-bottom: var(--space-lg);
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.alert-success {
  background: rgba(16, 185, 129, 0.1);
  color: var(--success);
  border: 1px solid var(--success);
}

.alert-error {
  background: rgba(239, 68, 68, 0.1);
  color: var(--danger);
  border: 1px solid var(--danger);
}

.alert-warning {
  background: rgba(245, 158, 11, 0.1);
  color: var(--warning);
  border: 1px solid var(--warning);
}

.alert-info {
  background: rgba(59, 130, 246, 0.1);
  color: var(--info);
  border: 1px solid var(--info);
}

/* ===== Loading Spinner ===== */
.spinner {
  width: 24px;
  height: 24px;
  border: 3px solid var(--border);
  border-top-color: var(--primary);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

.loading {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-2xl);
}

/* ===== Mobile Responsive ===== */
@media (max-width: 768px) {
  .sidebar {
    transform: translateX(-100%);
    position: fixed;
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
    padding: var(--space-md);
  }

  .page-header {
    flex-direction: column;
    align-items: flex-start;
  }

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

  .form-row {
    grid-template-columns: 1fr;
  }

  .table-container {
    font-size: 0.8125rem;
  }

  .table th,
  .table td {
    padding: var(--space-sm);
  }

  .mobile-menu-btn {
    display: flex;
  }
}

/* ===== Print Styles ===== */
@media print {
  .sidebar,
  .page-header,
  .btn,
  .no-print {
    display: none !important;
  }

  .main-content {
    margin-left: 0;
  }

  .card {
    box-shadow: none;
    border: 1px solid var(--border);
  }
}

/* ===== Utility Classes ===== */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--text-muted); }
.text-success { color: var(--success); }
.text-danger { color: var(--danger); }
.text-warning { color: var(--warning); }
.text-primary { color: var(--primary); }

.mt-1 { margin-top: var(--space-sm); }
.mt-2 { margin-top: var(--space-md); }
.mt-3 { margin-top: var(--space-lg); }
.mt-4 { margin-top: var(--space-xl); }

.mb-1 { margin-bottom: var(--space-sm); }
.mb-2 { margin-bottom: var(--space-md); }
.mb-3 { margin-bottom: var(--space-lg); }
.mb-4 { margin-bottom: var(--space-xl); }

.flex { display: flex; }
.flex-between { display: flex; justify-content: space-between; align-items: center; }
.flex-end { display: flex; justify-content: flex-end; align-items: center; }
.gap-1 { gap: var(--space-sm); }
.gap-2 { gap: var(--space-md); }
.gap-3 { gap: var(--space-lg); }

.hidden { display: none; }
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  border: 0;
}