/* =============================================
   Academic Summarizer — Enhanced Styles v2
   ============================================= */

/* ---- CSS Custom Properties (Light Mode) ---- */
:root {
  --primary: #4361ee;
  --primary-dark: #3354d4;
  --accent: #7209b7;

  --bg: #f8f9fc;
  --bg-secondary: #f0f4ff;
  --surface: #ffffff;
  --surface-hover: #f5f8ff;
  --border-color: rgba(0, 0, 0, 0.08);

  --text-primary: #1a1a2e;
  --text-secondary: #6c757d;

  --shadow-sm: 0 2px 16px rgba(67, 97, 238, 0.08);
  --shadow-md: 0 8px 24px rgba(67, 97, 238, 0.15);
  --shadow-lg: 0 16px 40px rgba(67, 97, 238, 0.2);

  --radius: 1rem;
  --radius-sm: 0.5rem;
  --transition: 0.2s ease;

  --navbar-bg: linear-gradient(135deg, #1a1a2e 0%, #16213e 60%, #0f3460 100%);
  --footer-bg: #16213e;
}

/* ---- Dark Mode ---- */
[data-theme="dark"] {
  --bg: #0d1117;
  --bg-secondary: #161b22;
  --surface: #1c2128;
  --surface-hover: #2d333b;
  --border-color: rgba(255, 255, 255, 0.1);

  --text-primary: #e6edf3;
  --text-secondary: #8b949e;

  --shadow-sm: 0 2px 16px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 16px 40px rgba(0, 0, 0, 0.5);
}

/* ---- Base ---- */
html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background-color: var(--bg);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  transition: background-color var(--transition), color var(--transition);
}

main { flex: 1; }

/* ---- Navbar ---- */
#main-nav {
  background: var(--navbar-bg);
  box-shadow: 0 2px 20px rgba(0,0,0,0.15);
  padding: 0.75rem 0;
}

#main-nav .navbar-brand {
  font-size: 1.2rem;
  letter-spacing: -0.3px;
}

#main-nav .nav-link {
  font-size: 0.9rem;
  font-weight: 500;
  padding: 0.4rem 0.8rem;
  border-radius: 0.5rem;
  transition: background var(--transition), color var(--transition);
}

#main-nav .nav-link:hover {
  background: rgba(255,255,255,0.1);
}

.theme-toggle {
  color: rgba(255,255,255,0.8) !important;
  width: 36px;
  height: 36px;
  display: flex !important;
  align-items: center;
  justify-content: center;
  border-radius: 50% !important;
  padding: 0 !important;
  transition: background var(--transition) !important;
}

.theme-toggle:hover {
  background: rgba(255,255,255,0.15) !important;
  color: #fff !important;
}

/* ---- Footer ---- */
.footer {
  background: var(--footer-bg);
  color: #adb5bd;
  border-top: 1px solid rgba(255,255,255,0.05);
}

/* ---- Cards ---- */
.card {
  background: var(--surface) !important;
  border-color: var(--border-color) !important;
  color: var(--text-primary);
  transition: box-shadow var(--transition), transform var(--transition), background var(--transition);
}

.paper-card:hover {
  box-shadow: var(--shadow-md) !important;
  transform: translateY(-2px);
}

.paper-title {
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  color: var(--text-primary);
}

/* ---- Hero ---- */
.hero-section { padding: 5rem 0; }

.text-gradient {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.feature-card {
  background: linear-gradient(135deg, #f0f4ff 0%, #faf5ff 100%) !important;
  border: 1px solid rgba(67, 97, 238, 0.15) !important;
}

[data-theme="dark"] .feature-card {
  background: linear-gradient(135deg, #1a2040 0%, #1e1030 100%) !important;
  border-color: rgba(67, 97, 238, 0.3) !important;
}

.feature-icon {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
}

.feature-icon-lg { color: var(--primary); line-height: 1; }

/* ---- Buttons ---- */
.btn-primary {
  background: linear-gradient(135deg, var(--primary), #7c3aed);
  border: none;
  font-weight: 500;
}

.btn-primary:hover {
  background: linear-gradient(135deg, #3354d4, #6d28d9);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(67, 97, 238, 0.3);
}

/* ---- Drop Zone ---- */
.drop-zone {
  border: 2px dashed var(--border-color);
  background: var(--bg-secondary);
  cursor: pointer;
  transition: border-color var(--transition), background var(--transition), transform var(--transition);
  border-radius: var(--radius);
  padding: 2.5rem 2rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}

.drop-zone:hover,
.drop-zone.drag-over {
  border-color: var(--primary);
  background: rgba(67, 97, 238, 0.05);
}

.drop-zone.drag-over {
  transform: scale(1.01);
  border-style: solid;
}

.drop-zone.has-file {
  border-color: #22c55e;
  background: rgba(34, 197, 94, 0.04);
  border-style: solid;
}

.drop-icon {
  font-size: 3rem;
  color: var(--text-secondary);
  transition: color var(--transition), transform var(--transition);
}

.drop-zone:hover .drop-icon,
.drop-zone.drag-over .drop-icon {
  color: var(--primary);
  transform: scale(1.1) translateY(-4px);
}

/* ---- File Preview ---- */
.file-preview {
  display: none;
  align-items: center;
  gap: 1rem;
  padding: 0.75rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  text-align: left;
}

.file-preview.visible { display: flex; }

/* ---- Progress Steps ---- */
.progress-steps { display: none; }
.progress-steps.visible { display: block; }

.step-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.6rem 0;
  color: var(--text-secondary);
  font-size: 0.9rem;
  transition: color var(--transition);
}

.step-item.active { color: var(--primary); font-weight: 500; }
.step-item.done   { color: #22c55e; }

.step-dot {
  width: 26px;
  height: 26px;
  border-radius: 50%;
  background: var(--border-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.72rem;
  font-weight: 600;
  flex-shrink: 0;
  transition: background var(--transition), color var(--transition);
}

.step-item.active .step-dot {
  background: var(--primary);
  color: white;
  animation: dot-pulse 1.5s infinite;
}

.step-item.done .step-dot {
  background: #22c55e;
  color: white;
}

@keyframes dot-pulse {
  0%, 100% { box-shadow: 0 0 0 0 rgba(67, 97, 238, 0.4); }
  50%       { box-shadow: 0 0 0 6px rgba(67, 97, 238, 0); }
}

/* ---- Toasts ---- */
.toast-container {
  position: fixed;
  top: 80px;
  right: 1.5rem;
  z-index: 9999;
  max-width: 380px;
  pointer-events: none;
}

.toast-container .toast { pointer-events: all; }

.toast {
  background: var(--surface) !important;
  color: var(--text-primary) !important;
  border: 1px solid var(--border-color) !important;
  box-shadow: var(--shadow-md) !important;
}

.toast-header {
  background: transparent !important;
  border-bottom-color: var(--border-color) !important;
  color: var(--text-primary) !important;
}

/* ---- Skeleton Loaders ---- */
.skeleton {
  background: linear-gradient(90deg,
    var(--border-color) 25%,
    var(--surface-hover) 50%,
    var(--border-color) 75%
  );
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}

@keyframes shimmer {
  0%   { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

.skeleton-text  { height: 1em;   margin-bottom: 0.5rem; }
.skeleton-title { height: 1.4em; width: 70%; margin-bottom: 0.75rem; }
.skeleton-card  { height: 200px; border-radius: var(--radius); }

/* ---- Summary Sections ---- */
.summary-section {
  background: var(--surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  padding: 1.5rem;
  margin-bottom: 1rem;
  transition: background var(--transition);
}

.section-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  font-size: 0.95rem;
}

/* ---- Tags ---- */
.tag-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem 0.6rem;
  border-radius: 2rem;
  font-size: 0.72rem;
  font-weight: 500;
  text-decoration: none;
  color: #fff;
  transition: opacity var(--transition);
}

.tag-badge:hover { opacity: 0.85; color: #fff; }

/* ---- AI Tag Chips (upload page) ---- */
.tag-chip {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.3rem 0.75rem;
  border-radius: 2rem;
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: transform 0.15s ease, opacity 0.15s ease, box-shadow 0.15s ease;
  white-space: nowrap;
}

.tag-chip--suggested {
  background: var(--bg-secondary);
  color: var(--primary);
  border: 1.5px dashed var(--primary);
}

.tag-chip--suggested:hover:not(:disabled) {
  background: rgba(67, 97, 238, 0.1);
  transform: translateY(-1px);
  box-shadow: 0 2px 8px rgba(67, 97, 238, 0.2);
}

.tag-chip--suggested.tag-chip--added {
  opacity: 0.4;
  cursor: default;
  transform: none;
}

.tag-chip--selected {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 1px 4px rgba(67, 97, 238, 0.3);
}

.tag-chip__remove {
  background: none;
  border: none;
  color: rgba(255, 255, 255, 0.75);
  padding: 0;
  margin-left: 0.15rem;
  display: inline-flex;
  align-items: center;
  cursor: pointer;
  font-size: 0.7rem;
  line-height: 1;
  transition: color 0.15s ease;
}

.tag-chip__remove:hover { color: #fff; }

[data-theme="dark"] .tag-chip--suggested {
  background: var(--surface-hover);
  color: #6b8af9;
  border-color: #6b8af9;
}

[data-theme="dark"] .tag-chip--suggested:hover:not(:disabled) {
  background: rgba(107, 138, 249, 0.15);
}

/* ---- Language Badge ---- */
.lang-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.15rem 0.5rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: 2rem;
  font-size: 0.72rem;
  color: var(--text-secondary);
}

/* ---- Citations ---- */
.citation-item {
  padding: 0.6rem 0.9rem;
  border-left: 3px solid var(--primary);
  background: var(--bg-secondary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-bottom: 0.4rem;
  font-size: 0.85rem;
  line-height: 1.5;
}

/* ---- Share Link ---- */
.share-link-input {
  font-family: monospace;
  font-size: 0.82rem;
  background: var(--bg-secondary) !important;
  color: var(--text-primary) !important;
  border-color: var(--border-color) !important;
}

/* ---- Dark Mode: Bootstrap overrides ---- */
[data-theme="dark"] .bg-body-secondary   { background-color: var(--bg-secondary) !important; }
[data-theme="dark"] .text-muted          { color: var(--text-secondary) !important; }
[data-theme="dark"] .text-body           { color: var(--text-primary) !important; }
[data-theme="dark"] .border-top,
[data-theme="dark"] .border-bottom       { border-color: var(--border-color) !important; }

[data-theme="dark"] .bg-success-subtle   { background-color: rgba(34, 197, 94, 0.15) !important; }
[data-theme="dark"] .text-success        { color: #4ade80 !important; }
[data-theme="dark"] .bg-secondary-subtle { background-color: rgba(139, 148, 158, 0.15) !important; }
[data-theme="dark"] .text-secondary      { color: var(--text-secondary) !important; }
[data-theme="dark"] .bg-primary-subtle   { background-color: rgba(67, 97, 238, 0.15) !important; }
[data-theme="dark"] .text-primary        { color: #6b8af9 !important; }
[data-theme="dark"] .bg-warning-subtle   { background-color: rgba(234, 179, 8, 0.15) !important; }
[data-theme="dark"] .text-warning        { color: #fbbf24 !important; }
[data-theme="dark"] .bg-info-subtle      { background-color: rgba(59, 130, 246, 0.15) !important; }
[data-theme="dark"] .text-info           { color: #60a5fa !important; }
[data-theme="dark"] .bg-danger-subtle    { background-color: rgba(239, 68, 68, 0.15) !important; }
[data-theme="dark"] .text-danger         { color: #f87171 !important; }

[data-theme="dark"] .dropdown-menu     { background: var(--surface) !important; border-color: var(--border-color) !important; }
[data-theme="dark"] .dropdown-item     { color: var(--text-primary) !important; }
[data-theme="dark"] .dropdown-item:hover { background: var(--surface-hover) !important; }
[data-theme="dark"] .dropdown-divider  { border-color: var(--border-color) !important; }

[data-theme="dark"] .form-control,
[data-theme="dark"] .form-select {
  background-color: var(--surface);
  border-color: var(--border-color);
  color: var(--text-primary);
}

[data-theme="dark"] .form-control:focus,
[data-theme="dark"] .form-select:focus {
  background-color: var(--surface);
  border-color: var(--primary);
  color: var(--text-primary);
  box-shadow: 0 0 0 0.2rem rgba(67, 97, 238, 0.25);
}

[data-theme="dark"] .form-control::placeholder { color: var(--text-secondary); }

[data-theme="dark"] .input-group-text {
  background: var(--surface-hover);
  border-color: var(--border-color);
  color: var(--text-secondary);
}

[data-theme="dark"] .btn-outline-secondary {
  color: var(--text-secondary);
  border-color: var(--border-color);
}

[data-theme="dark"] .btn-outline-secondary:hover {
  background: var(--surface-hover);
  color: var(--text-primary);
  border-color: var(--border-color);
}

[data-theme="dark"] .btn-outline-danger {
  color: #f87171;
  border-color: rgba(239, 68, 68, 0.4);
}

[data-theme="dark"] .btn-outline-danger:hover {
  background: rgba(239, 68, 68, 0.15);
  color: #f87171;
  border-color: rgba(239, 68, 68, 0.6);
}

[data-theme="dark"] .btn-outline-primary {
  color: #6b8af9;
  border-color: rgba(67, 97, 238, 0.4);
}

[data-theme="dark"] .btn-outline-primary:hover {
  background: rgba(67, 97, 238, 0.15);
  color: #6b8af9;
}

[data-theme="dark"] .btn-outline-warning {
  color: #fbbf24;
  border-color: rgba(251, 191, 36, 0.4);
}

[data-theme="dark"] .btn-outline-warning:hover {
  background: rgba(251, 191, 36, 0.15);
  color: #fbbf24;
}

[data-theme="dark"] .breadcrumb-item a     { color: #6b8af9; }
[data-theme="dark"] .breadcrumb-item.active { color: var(--text-secondary); }
[data-theme="dark"] .breadcrumb-item + .breadcrumb-item::before { color: var(--text-secondary); }

[data-theme="dark"] .alert-success {
  background-color: rgba(34, 197, 94, 0.12) !important;
  border-color: rgba(34, 197, 94, 0.25) !important;
  color: #4ade80 !important;
}

[data-theme="dark"] .alert-warning {
  background-color: rgba(234, 179, 8, 0.12) !important;
  border-color: rgba(234, 179, 8, 0.25) !important;
  color: #fbbf24 !important;
}

[data-theme="dark"] .alert-danger,
[data-theme="dark"] .alert-error {
  background-color: rgba(239, 68, 68, 0.12) !important;
  border-color: rgba(239, 68, 68, 0.25) !important;
  color: #f87171 !important;
}

[data-theme="dark"] .alert-info {
  background-color: rgba(59, 130, 246, 0.12) !important;
  border-color: rgba(59, 130, 246, 0.25) !important;
  color: #60a5fa !important;
}

[data-theme="dark"] .btn-close { filter: invert(1) grayscale(1); }

[data-theme="dark"] .pagination .page-link {
  background-color: var(--surface);
  border-color: var(--border-color);
  color: var(--text-primary);
}

[data-theme="dark"] .pagination .page-link:hover { background-color: var(--surface-hover); }
[data-theme="dark"] .pagination .active .page-link {
  background-color: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

[data-theme="dark"] .table { color: var(--text-primary); }
[data-theme="dark"] .table > :not(caption) > * > * { background-color: transparent; }
[data-theme="dark"] .table-hover > tbody > tr:hover > * { background-color: var(--surface-hover); }
[data-theme="dark"] .table > * { border-color: var(--border-color); }

[data-theme="dark"] .badge.bg-success { background-color: #166534 !important; }
[data-theme="dark"] .badge.bg-secondary { background-color: #374151 !important; }

/* ---- Utilities ---- */
.rounded-4 { border-radius: var(--radius) !important; }
.shadow-sm  { box-shadow: var(--shadow-sm) !important; }

/* ---- Alerts ---- */
.alert-error {
  --bs-alert-color: #842029;
  --bs-alert-bg: #f8d7da;
  --bs-alert-border-color: #f5c2c7;
}

/* ---- Responsive ---- */
@media (max-width: 768px) {
  .hero-section { padding: 3rem 0; }
  .display-4    { font-size: 2rem; }
  .toast-container { right: 1rem; left: 1rem; max-width: unset; }
}