/* ============================================================
   PDF Merger Pro — Design System
   Based on UI_DESIGN.md spec
   ============================================================ */

/* --- Google Fonts --- */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap');

/* --- CSS Custom Properties --- */
:root {
  /* Colors — Light Mode */
  --bg-primary:    #FFFFFF;
  --bg-surface:    #F8FAFC;
  --bg-surface-2:  #F1F5F9;
  --text-primary:  #0F172A;
  --text-secondary:#64748B;
  --border:        #E2E8F0;
  --border-focus:  #4F46E5;
  --accent:        #4F46E5;
  --accent-hover:  #4338CA;
  --accent-light:  #EEF2FF;
  --success:       #10B981;
  --success-light: #D1FAE5;
  --warning:       #F59E0B;
  --warning-light: #FEF3C7;
  --danger:        #F43F5E;
  --danger-hover:  #E11D48;
  --danger-light:  #FFE4E6;

  /* Shadows */
  --shadow-1: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-2: 0 4px 6px rgba(0,0,0,0.07), 0 2px 4px rgba(0,0,0,0.05);
  --shadow-3: 0 10px 25px rgba(0,0,0,0.10), 0 6px 10px rgba(0,0,0,0.06);
  --shadow-4: 0 20px 40px rgba(0,0,0,0.12);

  /* Spacing */
  --radius-sm: 6px;
  --radius:    10px;
  --radius-lg: 14px;
  --radius-xl: 20px;

  /* Transition */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --duration-fast: 150ms;
  --duration:      200ms;
  --duration-slow: 300ms;
}

[data-theme="dark"] {
  --bg-primary:    #0B1120;
  --bg-surface:    #1E293B;
  --bg-surface-2:  #263347;
  --text-primary:  #F1F5F9;
  --text-secondary:#94A3B8;
  --border:        #334155;
  --border-focus:  #818CF8;
  --accent:        #818CF8;
  --accent-hover:  #6366F1;
  --accent-light:  #1E1B4B;
  --success:       #34D399;
  --success-light: #064E3B;
  --warning:       #FCD34D;
  --warning-light: #451A03;
  --danger:        #FB7185;
  --danger-hover:  #F43F5E;
  --danger-light:  #4C0519;
}

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

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: 1rem;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color var(--duration) var(--ease),
              color var(--duration) var(--ease);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

h1 { font-size: 2rem;    font-weight: 700; line-height: 1.2; }
h2 { font-size: 1.5rem;  font-weight: 600; line-height: 1.3; }
h3 { font-size: 1.125rem;font-weight: 600; line-height: 1.4; }
h4 { font-size: 1rem;    font-weight: 600; }

a {
  color: var(--accent);
  text-decoration: none;
  transition: color var(--duration-fast) var(--ease);
}
a:hover { color: var(--accent-hover); }

/* --- Layout --- */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

main { flex: 1; }

/* --- Navbar --- */
.navbar {
  height: 64px;
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: background-color var(--duration) var(--ease),
              border-color var(--duration) var(--ease);
}

.navbar-inner {
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.navbar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
  white-space: nowrap;
}

.navbar-brand svg { flex-shrink: 0; }

.navbar-nav {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.navbar-nav a {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: color var(--duration-fast) var(--ease),
              background-color var(--duration-fast) var(--ease);
}

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

.navbar-nav a.active {
  color: var(--accent);
  background-color: var(--accent-light);
}

.navbar-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* Theme toggle */
.btn-theme {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-surface);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--duration-fast) var(--ease);
}

.btn-theme:hover {
  color: var(--text-primary);
  border-color: var(--border-focus);
  background: var(--accent-light);
}

/* Hamburger (mobile) */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  border-radius: var(--radius-sm);
  background: none;
  border: none;
}

.hamburger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-primary);
  border-radius: 2px;
  transition: all var(--duration) var(--ease);
}

/* Mobile nav drawer */
.mobile-nav {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 200;
}

.mobile-nav-overlay {
  position: absolute;
  inset: 0;
  background: rgba(0,0,0,0.5);
}

.mobile-nav-drawer {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  width: 280px;
  background: var(--bg-primary);
  padding: 24px;
  transform: translateX(-100%);
  transition: transform var(--duration-slow) var(--ease);
  overflow-y: auto;
}

.mobile-nav.open .mobile-nav-drawer {
  transform: translateX(0);
}

.mobile-nav.open { display: flex; }

.mobile-nav-links {
  list-style: none;
  margin-top: 24px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.mobile-nav-links a {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 16px;
  border-radius: var(--radius);
  font-weight: 500;
  color: var(--text-secondary);
}

.mobile-nav-links a:hover,
.mobile-nav-links a.active {
  color: var(--accent);
  background: var(--accent-light);
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: var(--radius);
  font-family: inherit;
  font-size: 0.9375rem;
  font-weight: 500;
  line-height: 1;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all var(--duration-fast) var(--ease);
  white-space: nowrap;
  text-decoration: none;
  user-select: none;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn-primary:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: #fff;
}

.btn-secondary {
  background: transparent;
  color: var(--accent);
  border-color: var(--accent);
}
.btn-secondary:hover {
  background: var(--accent-light);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border-color: transparent;
}
.btn-ghost:hover {
  background: var(--bg-surface);
  color: var(--text-primary);
}

.btn-danger {
  background: var(--danger);
  color: #fff;
  border-color: var(--danger);
}
.btn-danger:hover {
  background: var(--danger-hover);
  border-color: var(--danger-hover);
  color: #fff;
}

.btn-sm {
  padding: 6px 12px;
  font-size: 0.875rem;
  border-radius: var(--radius-sm);
}

.btn-lg {
  padding: 14px 28px;
  font-size: 1rem;
  border-radius: var(--radius);
}

.btn-icon {
  width: 36px;
  height: 36px;
  padding: 0;
  border-radius: 50%;
  border: 1px solid var(--border);
  background: var(--bg-surface);
  color: var(--text-secondary);
}
.btn-icon:hover {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-light);
}

.btn-icon.danger:hover {
  border-color: var(--danger);
  color: var(--danger);
  background: var(--danger-light);
}

.btn-full { width: 100%; }

/* Spinner inside button */
.btn .spinner {
  width: 16px;
  height: 16px;
  border: 2px solid rgba(255,255,255,0.4);
  border-top-color: #fff;
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

/* --- Cards --- */
.card {
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-1);
  transition: background-color var(--duration) var(--ease),
              border-color var(--duration) var(--ease);
}

.card-body { padding: 24px; }

.card-sm .card-body { padding: 16px; }

/* --- Upload Zone --- */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius-xl);
  background: var(--bg-surface);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: all var(--duration) var(--ease);
  position: relative;
  overflow: hidden;
}

.upload-zone:hover,
.upload-zone:focus-within {
  border-color: var(--accent);
  background: var(--accent-light);
}

.upload-zone.drag-over {
  border-color: var(--accent);
  background: var(--accent-light);
  transform: scale(1.01);
  box-shadow: var(--shadow-2);
}

.upload-zone.upload-error {
  border-color: var(--danger);
  background: var(--danger-light);
  animation: shake 0.4s var(--ease);
}

.upload-zone input[type="file"] {
  position: absolute;
  inset: 0;
  opacity: 0;
  cursor: pointer;
  width: 100%;
  height: 100%;
}

.upload-zone-icon {
  color: var(--accent);
  margin-bottom: 16px;
  display: block;
}

.upload-zone-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.upload-zone-subtitle {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.upload-zone-subtitle span {
  color: var(--accent);
  font-weight: 500;
  text-decoration: underline;
}

.upload-zone-hint {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: 10px;
}

/* --- File Cards (Merge list) --- */
.file-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  list-style: none;
}

.file-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-1);
  transition: box-shadow var(--duration-fast) var(--ease),
              background-color var(--duration) var(--ease),
              border-color var(--duration) var(--ease);
  cursor: default;
}

.file-card:hover {
  box-shadow: var(--shadow-2);
}

.file-card.sortable-ghost {
  opacity: 0.4;
  background: var(--accent-light);
  border-color: var(--accent);
}

.file-card.sortable-chosen {
  box-shadow: var(--shadow-3);
  transform: rotate(1.5deg);
  opacity: 0.95;
  z-index: 10;
}

.file-card-grip {
  color: var(--text-secondary);
  cursor: grab;
  padding: 4px;
  flex-shrink: 0;
  touch-action: none;
}

.file-card-grip:active { cursor: grabbing; }

.file-card-icon {
  color: var(--accent);
  flex-shrink: 0;
}

.file-card-info {
  flex: 1;
  min-width: 0;
}

.file-card-name {
  font-weight: 500;
  font-size: 0.9375rem;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  color: var(--text-primary);
}

.file-card-meta {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.file-card-remove {
  flex-shrink: 0;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--duration-fast) var(--ease);
}

.file-card-remove:hover {
  background: var(--danger-light);
  color: var(--danger);
}

/* --- Page Thumbnail Grid --- */
.thumbnail-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 16px;
}

.thumbnail-card {
  background: var(--bg-surface);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease);
  position: relative;
  user-select: none;
}

.thumbnail-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-2);
  transform: translateY(-2px);
}

.thumbnail-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-light);
}

.thumbnail-card.sortable-ghost {
  opacity: 0.3;
  border: 2px dashed var(--accent);
}

.thumbnail-card.sortable-chosen {
  box-shadow: var(--shadow-3);
  z-index: 10;
  opacity: 0.95;
}

.thumbnail-img-wrapper {
  aspect-ratio: 3/4;
  background: #fff;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
}

.thumbnail-img-wrapper img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
}

/* Skeleton shimmer while loading */
.thumbnail-skeleton {
  aspect-ratio: 3/4;
  background: linear-gradient(
    90deg,
    var(--bg-surface-2) 25%,
    var(--border) 50%,
    var(--bg-surface-2) 75%
  );
  background-size: 200% 100%;
  animation: shimmer 1.4s infinite;
}

.thumbnail-check {
  position: absolute;
  top: 8px;
  right: 8px;
  width: 24px;
  height: 24px;
  background: var(--accent);
  border-radius: 50%;
  display: none;
  align-items: center;
  justify-content: center;
  color: #fff;
}

.thumbnail-card.selected .thumbnail-check {
  display: flex;
}

.thumbnail-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  background: var(--bg-surface);
  border-top: 1px solid var(--border);
}

.thumbnail-label {
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.thumbnail-actions {
  display: flex;
  gap: 4px;
  opacity: 0;
  transition: opacity var(--duration-fast) var(--ease);
}

.thumbnail-card:hover .thumbnail-actions,
.thumbnail-card.selected .thumbnail-actions {
  opacity: 1;
}

.thumbnail-action-btn {
  width: 28px;
  height: 28px;
  border: none;
  background: transparent;
  color: var(--text-secondary);
  border-radius: var(--radius-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--duration-fast) var(--ease);
}

.thumbnail-action-btn:hover {
  background: var(--bg-surface-2);
  color: var(--accent);
}

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

/* Rotation visual */
.thumbnail-img-wrapper img {
  transition: transform var(--duration) var(--ease);
}

/* --- Progress Bar --- */
.progress-wrap {
  background: var(--bg-surface-2);
  border-radius: 999px;
  height: 8px;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--accent), #7C3AED);
  transition: width var(--duration) var(--ease);
  min-width: 4px;
}

.progress-label {
  font-size: 0.8125rem;
  color: var(--text-secondary);
  margin-top: 6px;
  text-align: center;
}

/* --- Section Headers --- */
.section-label {
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-secondary);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* --- Page Header (tool pages) --- */
.page-header {
  padding: 40px 0 32px;
}

.page-header h1 {
  font-size: 1.75rem;
  margin-bottom: 6px;
}

.page-header p {
  color: var(--text-secondary);
  font-size: 1rem;
}

/* --- Toast Notifications --- */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  z-index: 9999;
  display: flex;
  flex-direction: column;
  gap: 10px;
  pointer-events: none;
}

.toast {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-4);
  min-width: 280px;
  max-width: 360px;
  pointer-events: all;
  animation: toast-in var(--duration-slow) var(--ease) forwards;
}

.toast.removing {
  animation: toast-out var(--duration) var(--ease) forwards;
}

.toast-icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  margin-top: 1px;
}

.toast-body { flex: 1; }

.toast-title {
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--text-primary);
}

.toast-message {
  font-size: 0.875rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

.toast-close {
  flex-shrink: 0;
  background: none;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  padding: 2px;
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
}

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

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

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

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

/* --- Empty State --- */
.empty-state {
  text-align: center;
  padding: 64px 24px;
  color: var(--text-secondary);
}

.empty-state-icon {
  margin: 0 auto 16px;
  color: var(--border);
  display: block;
}

.empty-state-title {
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-primary);
  margin-bottom: 6px;
}

.empty-state-text {
  font-size: 0.9375rem;
}

/* --- Badge --- */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 2px 8px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 600;
}

.badge-accent {
  background: var(--accent-light);
  color: var(--accent);
}

/* --- Divider --- */
.divider {
  border: none;
  border-top: 1px solid var(--border);
  margin: 24px 0;
}

/* --- Input --- */
.input-group {
  display: flex;
  align-items: stretch;
}

.input-group .form-input {
  border-radius: var(--radius) 0 0 var(--radius);
  border-right: none;
  flex: 1;
}

.input-group .input-addon {
  display: flex;
  align-items: center;
  padding: 0 14px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 0 var(--radius) var(--radius) 0;
  color: var(--text-secondary);
  font-size: 0.9375rem;
  white-space: nowrap;
}

.form-input {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-primary);
  color: var(--text-primary);
  font-family: inherit;
  font-size: 0.9375rem;
  transition: border-color var(--duration-fast) var(--ease),
              box-shadow var(--duration-fast) var(--ease);
  outline: none;
}

.form-input:focus {
  border-color: var(--border-focus);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 15%, transparent);
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-primary);
  margin-bottom: 6px;
}

/* Radio group */
.radio-group {
  display: flex;
  gap: 12px;
}

.radio-option {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: pointer;
  transition: all var(--duration-fast) var(--ease);
  font-size: 0.9375rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.radio-option input[type="radio"] { display: none; }

.radio-option.selected {
  border-color: var(--accent);
  background: var(--accent-light);
  color: var(--accent);
}

/* --- Toolbar --- */
.toolbar {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-wrap: wrap;
}

/* --- File Info Bar --- */
.file-info-bar {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 18px;
  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
}

.file-info-bar-icon { color: var(--accent); }

.file-info-bar-details { flex: 1; }

.file-info-bar-name {
  font-weight: 600;
  color: var(--text-primary);
  font-size: 0.9375rem;
}

.file-info-bar-meta {
  font-size: 0.8125rem;
  color: var(--text-secondary);
}

/* --- Privacy Badge --- */
.privacy-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  background: var(--success-light);
  color: var(--success);
  border-radius: 999px;
  font-size: 0.8125rem;
  font-weight: 600;
}

/* --- Hero Section --- */
.hero {
  padding: 80px 0 64px;
  text-align: center;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 999px;
  font-size: 0.8125rem;
  font-weight: 600;
  margin-bottom: 24px;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  margin-bottom: 16px;
  line-height: 1.1;
}

.hero h1 span {
  background: linear-gradient(135deg, var(--accent), #7C3AED);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--text-secondary);
  max-width: 540px;
  margin: 0 auto 36px;
  line-height: 1.7;
}

.hero-cta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}

/* --- Feature Cards (landing) --- */
.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  padding: 32px 24px;
  background: var(--bg-primary);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-1);
  transition: all var(--duration) var(--ease);
  text-decoration: none;
  display: block;
  color: inherit;
}

.feature-card:hover {
  box-shadow: var(--shadow-3);
  transform: translateY(-4px);
  border-color: var(--accent);
  color: inherit;
}

.feature-card-icon {
  width: 56px;
  height: 56px;
  background: var(--accent-light);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  margin-bottom: 20px;
}

.feature-card h3 {
  margin-bottom: 8px;
  font-size: 1.125rem;
}

.feature-card p {
  color: var(--text-secondary);
  font-size: 0.9375rem;
  line-height: 1.6;
}

.feature-card-arrow {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  margin-top: 16px;
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--accent);
}

/* --- How it works --- */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  position: relative;
}

.steps-grid::before {
  content: '';
  position: absolute;
  top: 28px;
  left: calc(50% / 3 + 16px);
  right: calc(50% / 3 + 16px);
  height: 2px;
  background: var(--border);
}

.step {
  text-align: center;
  padding: 24px;
}

.step-number {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: var(--accent-light);
  border: 2px solid var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 auto 16px;
  position: relative;
  z-index: 1;
}

.step h3 { margin-bottom: 8px; }
.step p { color: var(--text-secondary); font-size: 0.9375rem; }

/* --- Why section --- */
.why-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.why-item {
  text-align: center;
  padding: 24px 16px;
}

.why-item-icon {
  font-size: 2rem;
  margin-bottom: 12px;
  display: block;
}

.why-item h4 { margin-bottom: 6px; }
.why-item p  { color: var(--text-secondary); font-size: 0.875rem; }

/* --- Footer --- */
footer {
  padding: 32px 0;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

footer a {
  color: var(--text-secondary);
}

footer a:hover { color: var(--accent); }

/* --- Section Wrapper --- */
.section {
  padding: 64px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-header h2 {
  margin-bottom: 8px;
}

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

.section-header .section-tag {
  display: inline-block;
  padding: 4px 14px;
  background: var(--accent-light);
  color: var(--accent);
  border-radius: 999px;
  font-size: 0.8125rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 12px;
}

/* --- Animations --- */
@keyframes spin {
  to { transform: rotate(360deg); }
}

@keyframes shimmer {
  from { background-position: 200% 0; }
  to   { background-position: -200% 0; }
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%       { transform: translateX(-6px); }
  40%       { transform: translateX(6px); }
  60%       { transform: translateX(-4px); }
  80%       { transform: translateX(4px); }
}

@keyframes toast-in {
  from {
    opacity: 0;
    transform: translateX(20px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes toast-out {
  from {
    opacity: 1;
    transform: translateX(0);
  }
  to {
    opacity: 0;
    transform: translateX(20px);
  }
}

@keyframes fade-in-up {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in-up {
  animation: fade-in-up var(--duration-slow) var(--ease) both;
}

/* --- Utilities --- */
.mt-4  { margin-top: 16px; }
.mt-6  { margin-top: 24px; }
.mt-8  { margin-top: 32px; }
.mb-4  { margin-bottom: 16px; }
.mb-6  { margin-bottom: 24px; }
.flex  { display: flex; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }
.gap-4 { gap: 16px; }
.text-sm   { font-size: 0.875rem; }
.text-muted { color: var(--text-secondary); }
.font-semibold { font-weight: 600; }
.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;
}

/* --- Focus visible (accessibility) --- */
:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

/* --- Reduced motion --- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ============================================================
   Responsive
   ============================================================ */

@media (max-width: 1023px) {
  .feature-grid,
  .steps-grid,
  .why-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .steps-grid::before { display: none; }

  .hero h1 { font-size: 2.25rem; }
}

@media (max-width: 767px) {
  .container { padding: 0 16px; }

  .navbar-nav,
  .navbar-actions { display: none; }

  .hamburger { display: flex; }

  .hero { padding: 48px 0 40px; }
  .hero h1 { font-size: 1.875rem; }
  .hero-subtitle { font-size: 1rem; }

  .feature-grid,
  .steps-grid,
  .why-grid {
    grid-template-columns: 1fr;
  }

  .section { padding: 40px 0; }
  .page-header { padding: 24px 0 20px; }
  .page-header h1 { font-size: 1.5rem; }

  .thumbnail-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .radio-group { flex-direction: column; }

  .toast-container {
    left: 16px;
    right: 16px;
    bottom: 16px;
  }

  .toast { min-width: unset; max-width: unset; }
}