/* ==========================================================================
   Newsletter Platform - Design System & Styles (Module 1)
   Mobile-First, Light/Dark Mode, Clean Modern Aesthetics
   ========================================================================== */

:root {
  /* Light Theme Color Tokens */
  --bg-body: #f8fafc;
  --bg-surface: #ffffff;
  --bg-surface-hover: #f1f5f9;
  --bg-header: rgba(255, 255, 255, 0.85);
  --border-color: #e2e8f0;
  --border-focus: #3b82f6;

  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --text-inverse: #ffffff;

  --color-primary: #2563eb;
  --color-primary-hover: #1d4ed8;
  --color-primary-light: #eff6ff;

  --color-success: #10b981;
  --color-success-bg: #ecfdf5;
  --color-warning: #f59e0b;
  --color-warning-bg: #fffbeb;
  --color-error: #ef4444;
  --color-error-bg: #fef2f2;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --radius-full: 9999px;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -1px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --transition-fast: 0.15s ease;
  --transition-normal: 0.25s ease;
}

[data-theme="dark"] {
  /* Dark Theme Color Tokens */
  --bg-body: #0f172a;
  --bg-surface: #1e293b;
  --bg-surface-hover: #334155;
  --bg-header: rgba(30, 41, 59, 0.85);
  --border-color: #334155;
  --border-focus: #60a5fa;

  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --text-inverse: #0f172a;

  --color-primary: #3b82f6;
  --color-primary-hover: #60a5fa;
  --color-primary-light: rgba(59, 130, 246, 0.15);

  --color-success: #34d399;
  --color-success-bg: rgba(52, 211, 153, 0.12);
  --color-warning: #fbbf24;
  --color-warning-bg: rgba(251, 191, 36, 0.12);
  --color-error: #f87171;
  --color-error-bg: rgba(248, 113, 113, 0.12);

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.5);
}

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

html, body {
  height: 100%;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-body);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* App Shell Layout */
.app-shell {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--bg-header);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.75rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: var(--text-primary);
  font-size: 1.15rem;
  font-weight: 600;
}

.brand-icon {
  width: 26px;
  height: 26px;
  color: var(--color-primary);
}

.app-nav {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav-link {
  padding: 0.4rem 0.8rem;
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.925rem;
  font-weight: 500;
  border-radius: var(--radius-sm);
  transition: all var(--transition-fast);
}

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

.nav-link.active {
  color: var(--color-primary);
  background-color: var(--color-primary-light);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

/* Theme Toggle Button */
.theme-toggle {
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.45rem;
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-fast);
}

.theme-toggle:hover {
  color: var(--text-primary);
  background-color: var(--bg-surface-hover);
}

.sun-icon, .moon-icon {
  width: 18px;
  height: 18px;
}

[data-theme="light"] .sun-icon { display: none; }
[data-theme="light"] .moon-icon { display: block; }
[data-theme="dark"] .sun-icon { display: block; }
[data-theme="dark"] .moon-icon { display: none; }

/* User Menu */
.user-menu {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.user-profile-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-decoration: none;
  color: var(--text-primary);
  font-size: 0.875rem;
  font-weight: 500;
}

.avatar-initial {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-full);
  background-color: var(--color-primary);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  font-size: 0.875rem;
}

/* Main Content Area */
.app-content {
  flex: 1;
  padding: 2rem 1.25rem;
}

.content-container {
  max-width: 1200px;
  margin: 0 auto;
}

/* Footer */
.app-footer {
  border-top: 1px solid var(--border-color);
  background-color: var(--bg-surface);
  padding: 1.5rem 1.25rem;
  margin-top: auto;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
}

.footer-meta {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.footer-meta code {
  background-color: var(--bg-body);
  padding: 0.1rem 0.4rem;
  border-radius: 4px;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.6rem 1.2rem;
  font-size: 0.925rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: all var(--transition-fast);
}

.btn-sm {
  padding: 0.4rem 0.85rem;
  font-size: 0.85rem;
}

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

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

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

.btn-secondary:hover:not(:disabled) {
  background-color: var(--border-color);
  color: var(--text-primary);
}

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

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

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

.btn-success:hover:not(:disabled) {
  opacity: 0.9;
}

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

.btn-danger:hover:not(:disabled) {
  opacity: 0.9;
}

.btn:disabled, .btn.disabled, button:disabled {
  opacity: 0.55;
  cursor: not-allowed !important;
  pointer-events: none;
  filter: grayscale(0.3);
}

[data-theme="dark"] .btn-outline {
  background-color: var(--bg-surface);
  border-color: #64748b;
  color: #f8fafc;
}

[data-theme="dark"] .btn-outline:hover:not(:disabled) {
  background-color: #334155;
  border-color: #60a5fa;
  color: #60a5fa;
}

[data-theme="dark"] .btn-secondary {
  background-color: #334155;
  color: #f8fafc;
  border-color: #475569;
}

[data-theme="dark"] .btn-secondary:hover:not(:disabled) {
  background-color: #475569;
  color: #ffffff;
}

[data-theme="dark"] .btn:disabled, [data-theme="dark"] .btn.disabled, [data-theme="dark"] button:disabled {
  opacity: 0.6;
  background-color: #1e293b;
  border-color: #475569;
  color: #cbd5e1;
}



/* Cards & Surface Container */
.card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  transition: background-color var(--transition-normal), border-color var(--transition-normal);
}

.card-header {
  margin-bottom: 1.25rem;
}

.card-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-primary);
}

.card-subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-top: 0.25rem;
}

/* Forms */
.form-group {
  margin-bottom: 1.25rem;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 0.4rem;
}

.form-control {
  width: 100%;
  padding: 0.65rem 0.85rem;
  font-size: 0.95rem;
  font-family: inherit;
  color: var(--text-primary);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-control:focus {
  outline: none;
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px var(--color-primary-light);
}

.form-help {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
}

/* Alert Banners */
.alert {
  padding: 0.85rem 1.15rem;
  border-radius: var(--radius-sm);
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.alert-success { background-color: var(--color-success-bg); color: var(--color-success); border: 1px solid var(--color-success); }
.alert-error { background-color: var(--color-error-bg); color: var(--color-error); border: 1px solid var(--color-error); }
.alert-warning { background-color: var(--color-warning-bg); color: var(--color-warning); border: 1px solid var(--color-warning); }
.alert-info { background-color: var(--color-primary-light); color: var(--color-primary); border: 1px solid var(--color-primary); }

.alert-close {
  background: none;
  border: none;
  font-size: 1.25rem;
  cursor: pointer;
  color: inherit;
  opacity: 0.7;
}

.alert-close:hover { opacity: 1; }

/* Badges */
.badge {
  display: inline-block;
  padding: 0.2rem 0.55rem;
  font-size: 0.75rem;
  font-weight: 600;
  border-radius: var(--radius-full);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.badge-admin { background-color: #8b5cf6; color: #ffffff; }
.badge-active { background-color: var(--color-success-bg); color: var(--color-success); }
.badge-inactive { background-color: var(--color-error-bg); color: var(--color-error); }
.badge-role { background-color: var(--bg-surface-hover); color: var(--text-secondary); border: 1px solid var(--border-color); }

/* Tables */
.table-responsive {
  width: 100%;
  overflow-x: auto;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

.table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.9rem;
}

.table th, .table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border-color);
}

.table th {
  background-color: var(--bg-surface-hover);
  color: var(--text-secondary);
  font-weight: 600;
}

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

/* Landing Page Grid */
.landing-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.5rem;
  align-items: center;
}

@media (min-width: 850px) {
  .landing-grid {
    grid-template-columns: 1.2fr 0.8fr;
  }
}

.hero-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.2;
  color: var(--text-primary);
  margin-bottom: 1rem;
}

.hero-title span {
  color: var(--color-primary);
}

.hero-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 1.5rem;
}

.feature-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-top: 1.5rem;
}

.feature-item {
  background-color: var(--bg-surface);
  padding: 1rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
}

.feature-item h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 0.25rem;
}

.feature-item p {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Utility Utilities */
.text-center { text-align: center; }
.mt-1 { margin-top: 0.5rem; }
.mt-2 { margin-top: 1rem; }
.mt-3 { margin-top: 1.5rem; }
.mb-2 { margin-bottom: 1rem; }
.flex { display: flex; }
.gap-2 { gap: 0.5rem; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }

/* Event Date/Time Layout (Module 4) */
.event-datetime-container {
  display: flex;
  flex-direction: column;
}

.event-datetime-row {
  display: grid;
  grid-template-columns: 3fr 2fr;
  gap: 1rem;
}

@media (max-width: 576px) {
  .event-datetime-row {
    grid-template-columns: 1fr;
    gap: 0;
  }
}

/* Table Actions Dropdown (Module 4) */
.actions-dropdown {
  position: relative;
  display: inline-block;
}

.actions-dropdown summary {
  list-style: none;
  cursor: pointer;
  user-select: none;
  white-space: nowrap;
}

.actions-dropdown summary::-webkit-details-marker {
  display: none;
}

.actions-menu {
  position: absolute;
  right: 0;
  top: calc(100% + 4px);
  z-index: 200;
  min-width: 170px;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-md);
  padding: 0.35rem 0;
}

.actions-menu-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  width: 100%;
  padding: 0.5rem 0.85rem;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-primary);
  text-align: left;
  background: none;
  border: none;
  cursor: pointer;
  text-decoration: none;
  font-family: inherit;
  box-sizing: border-box;
  transition: background-color var(--transition-fast), color var(--transition-fast);
}

.actions-menu-item:hover,
.actions-menu-item:focus {
  background-color: var(--bg-surface-hover);
  color: var(--color-primary);
  outline: none;
}

.table td {
  position: relative;
}

.table tr:has(.actions-dropdown[open]) {
  position: relative;
  z-index: 100;
}

/* Shared Selection Chips & Checkbox Labels */
label:has(input[type="checkbox"]),
label:has(input[type="radio"]) {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--text-primary);
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  padding: 0.4rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  user-select: none;
  transition: all var(--transition-fast);
}

label:has(input[type="checkbox"]:hover:not(:disabled)),
label:has(input[type="radio"]:hover:not(:disabled)) {
  background-color: var(--bg-surface-hover);
  border-color: var(--color-primary);
}

/* Checked State */
label:has(input[type="checkbox"]:checked),
label:has(input[type="radio"]:checked) {
  background-color: var(--color-primary-light);
  border-color: var(--color-primary);
  color: var(--color-primary);
  font-weight: 600;
}

[data-theme="dark"] label:has(input[type="checkbox"]:checked),
[data-theme="dark"] label:has(input[type="radio"]:checked) {
  background-color: rgba(59, 130, 246, 0.25);
  border-color: #60a5fa;
  color: #93c5fd;
}

/* Disabled State */
label:has(input[type="checkbox"]:disabled),
label:has(input[type="radio"]:disabled) {
  opacity: 0.6;
  cursor: not-allowed;
  background-color: var(--bg-body);
  border-color: var(--border-color);
  color: var(--text-muted);
}

[data-theme="dark"] label:has(input[type="checkbox"]:disabled),
[data-theme="dark"] label:has(input[type="radio"]:disabled) {
  opacity: 0.55;
  background-color: #1e293b;
  border-color: #334155;
  color: #94a3b8;
}

/* Checkbox Inputs */
input[type="checkbox"], input[type="radio"] {
  accent-color: var(--color-primary);
  width: 1rem;
  height: 1rem;
  cursor: pointer;
}

input[type="checkbox"]:disabled, input[type="radio"]:disabled {
  cursor: not-allowed;
}