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

:root {
  --primary: #2f2ca0;
  --primary-dark: #4698e5;
  --accent: #facc15;
  --bg-light: #f9fafb;
  --bg-dark: #111827;
  --text-light: #f3f4f6;
  --text-dark: #1f2937;
  --gray: #6b7280;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: linear-gradient(135deg, #dbeafe 0%, #e0e7ff 100%);
  min-height: 100vh;
  padding: 1rem;
  color: var(--text-dark);
}

.container {
  max-width: 1280px;
  margin: 0 auto;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.5rem;
}

.navbar-right-links {
  display: flex;
  gap: 0.5rem;
  align-items: center;
}

@media (max-width: 768px) {
  .navbar {
    display: none;
  }
}

.nav-item {
  text-decoration: none;
  background-color: #3b82f6;
  color: white;
  border: none;
  padding: 10px 18px;
  margin: 5px;
  cursor: pointer;
  font-size: 14px;
  border-radius: 4px;
  transition: background-color 0.3s, transform 0.2s;
}

/* Header Styles */
.header {
  background-color: #7298e5;
  border-radius: 16px;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.15);
  padding: 1.8rem;
  margin-bottom: 1.5rem;
}
/* Header Styles */
.header {
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  padding: 1.5rem;
  margin-bottom: 1.5rem;
  display: flex;
  justify-content: space-between;
  align-items: start;
}

.menu-btn {
  width: 2rem;
  height: 2rem;
  color: #3b82f6;
}

#menu-close-btn {
  display: none;
  position: fixed;
  color: white;
  top: 1.5rem;
  right: 1.5rem;
  z-index: 99999;
}

#menu-items-container {
  background: #3b82f6;
  display: none;
  position: fixed;
  top: 0;
  right: 0;
  left: 0;
  bottom: 0;
  width: 100%;
  z-index: 99999;
  min-height: 100vh;

  flex-direction: column;
  gap: 1.5rem;
  justify-content: center;
  align-items: center;
}

body.dark-mode #menu-items-container {
  background: #1f2937;
}
.menu-item {
  text-decoration: none;
  color: white;
  font-size: larger;
}

@media (min-width: 768px) {
  .menu {
    display: none;
  }
}

.header-content {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.header-title i {
  color: var(--primary);
}
/* Footer container */
#footer-outer {
  background: linear-gradient(90deg, var(--primary-dark), var(--primary));
  color: var(--text-light);
  padding: 20px;
  text-align: center;
  font-family: Arial, sans-serif;
  margin-top: 15px;
  border-radius: 12px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
}

/* Footer inner container */
.footer-inner {
  margin-bottom: 1rem;
}

/* Footer buttons */
.footer-inner button {
  background: rgba(255, 255, 255, 0.15);
  color: white;
  border: none;
  padding: 10px 18px;
  margin: 5px;
  cursor: pointer;
  font-size: 14px;
  border-radius: 4px;
  transition: background-color 0.3s, transform 0.2s;
}

.footer-inner button:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: scale(1.05);
}

/* Social media section */
.footer-social {
  margin: 1rem 0;
}

.footer-social h3 {
  margin: 10px 0;
  color: #6b7280;
  font-size: 1rem;
}

/* Social media icons */
.footer-social a {
  text-decoration: none;
  font-size: 20px;
  transition: transform 0.3s, opacity 0.3s;
  margin: 0 10px;
}

.footer-social a:hover {
  transform: scale(1.3);
  opacity: 0.8;
}

/* Instagram icon */
.fa-instagram {
  color: #e4405f;
}

/* LinkedIn icon */
.fa-linkedin {
  color: #0077b5;
}

/* Twitter icon */
.fa-twitter {
  color: #1da1f2;
}

/* Copyright text */
#footer-outer h3 {
  margin-top: 20px;
  font-size: 14px;
  color: #555;
}

/* Dark mode styles */
body.dark-mode #footer-outer {
    background: linear-gradient(90deg, #1f2937, #111827);
    color: var(--text-light);
    box-shadow: 0 4px 6px -1px rgba(255, 255, 255, 0.05);
}

body.dark-mode .footer-inner button {
  background-color: #3b82f6;
}

body.dark-mode .footer-inner button:hover {
  background-color: #2563eb;
}

body.dark-mode .footer-social h3 {
  color: #9ca3af;
}

body.dark-mode #footer-outer h3 {
  color: #d1d5db;
}

@media (min-width: 768px) {
  .header-content {
    flex-direction: row;
    align-items: center;
    justify-content: space-between;
  }
}

.header-title {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.875rem;
  font-weight: bold;
  color: #1f2937;
  margin-bottom: 0.25rem;
}

.header-title i {
  color: #a5bef5;
}

.header-subtitle {
  color: #6b7280;
  margin-top: 0.25rem;
}

.add-btn {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  border: none;
  padding: 0.6rem 1.2rem;
  border-radius: 10px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: transform 0.25s ease, box-shadow 0.25s ease;
  font-size: 0.9rem;
}

.add-btn:hover {
  background: #1d4ed8;
  transform: translateY(-2px);
  box-shadow: 0 6px 14px rgba(99, 102, 241, 0.3);
}

.btn-secondary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: var(--text-light);
  border: none;
  padding: 10px 20px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  transition: background 0.3s ease, transform 0.2s ease;
}

.btn-secondary:hover {
  background: linear-gradient(135deg, 
              color-mix(in srgb, var(--primary) 85%, black), 
              color-mix(in srgb, var(--primary-dark) 85%, black));
  transform: translateY(-2px);
}

.btn-secondary:active {
  transform: translateY(0);
}
/* Search and Filter Bar */
.search-bar {
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  padding: 1rem;
  margin-bottom: 1.5rem;
}

.search-content {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
#footer-outer {
  margin-top: 15px;
}

@media (min-width: 768px) {
  .search-content {
    flex-direction: row;
  }
}

.search-input-container {
  flex: 1;
  position: relative;
}

.search-input {
  width: 100%;
  padding: 0.5rem 0.5rem 0.5rem 2.5rem;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  font-size: 0.875rem;
}

.search-input:focus {
  outline: none;
  border-color: #c4cde2;
  box-shadow: 0 0 0 2px rgba(217, 218, 221, 0.2);
}

.search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: #9ca3af;
}

.filter-container {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.filter-select {
  padding: 0.5rem 0.50rem;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  font-size: 0.875rem;
}

.filter-select:focus {
  outline: none;
  border-color: #2563eb;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.2);
}

/* Main Grid */
.main-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}
#footer-outer {
  margin-top: 15px;
}

@media (min-width: 1024px) {
  .main-grid {
    grid-template-columns: 2fr 1fr;
  }
}

/* Papers List */
.papers-section {
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  padding: 1.5rem;
}

.papers-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: #1f2937;
  margin-bottom: 1rem;
}

.empty-state {
  text-align: center;
  padding: 3rem 0;
  color: #6b7280;
}

.empty-state i {
  font-size: 3rem;
  color: #d1d5db;
  margin-bottom: 1rem;
}

.papers-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-top: 20px;
}

.paper-card {
  background-color: #7298e5;
  border: 1px solid #141414;
  border-radius: 12px;
  padding: 1.2rem;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.3s ease;
}

.paper-card:hover {
  border-color: #d1d5db;
  transform: translateY(-3px);
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.06);
}

.paper-card.selected {
  border-color: #0772eb;
  background: #091737;
}

.paper-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 0.5rem;
  gap: 0.5rem;
}

.paper-title {
  font-weight: 600;
  color: #dde6f1;
  flex: 1;
}

.paper-actions {
  display: flex;
  gap: 0.25rem;
  flex-shrink: 0;
}

.paper-action-btn {
  background: none;
  border: none;
  padding: 0.25rem;
  cursor: pointer;
  color: #6b7280;
  transition: color 0.2s;
  font-size: 0.875rem;
}

.paper-action-btn:hover {
  color: #2563eb;
}

.paper-action-btn.delete:hover {
  color: #dc2626;
}

.paper-authors {
  color: #6b7280;
  font-size: 0.875rem;
  margin-bottom: 0.5rem;
}

.paper-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.75rem;
  color: #6b7280;
}

.topic-badge {
  background: rgb(210, 210, 219);
  color: #1e40af;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  color: var(--primary-dark);
}

.year-badge {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

.tag-badge {
  background: rgb(194, 201, 214);
  color: var(--gray);
  padding: 0.25rem 0.5rem;
  border-radius: 6px;
}

/* Paper Details */
.details-section {
  background: white;
  border-radius: 12px;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  padding: 1.5rem;
  position: sticky;
  top: 1rem;
}

.details-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  margin-bottom: 1rem;
}

.details-title {
  font-size: 1.25rem;
  font-weight: 600;
  color: #1f2937;
}

.close-btn {
  background: none;
  border: none;
  color: #6b7280;
  cursor: pointer;
  padding: 0.25rem;
  font-size: 1.25rem;
}

.close-btn:hover {
  color: #1f2937;
}

.details-content {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.detail-section h3 {
  font-weight: 600;
  color: #1f2937;
  margin-bottom: 0.25rem;
}

.detail-section h4 {
  font-weight: 500;
  color: #374151;
  margin-bottom: 0.25rem;
  font-size: 0.875rem;
}

.detail-section p {
  color: #6b7280;
  font-size: 0.875rem;
}

.paper-link {
  color: #2563eb;
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.875rem;
  transition: color 0.2s;
}

.paper-link:hover {
  color: #1d4ed8;
}

.details-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
  font-size: 0.875rem;
}

.tags-container {
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem;
}

.detail-tag {
  background: #f3f4f6;
  color: #6b7280;
  padding: 0.25rem 0.5rem;
  border-radius: 4px;
  font-size: 0.75rem;
}

/* Citation Generator */
.citation-section {
  border-top: 1px solid #e5e7eb;
  padding-top: 1rem;
}

.citation-item {
  margin-bottom: 0.5rem;
}

.citation-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.25rem;
}

.citation-style {
  font-size: 0.875rem;
  font-weight: 500;
  color: #6b7280;
}

.copy-btn {
  background: none;
  border: none;
  color: #2563eb;
  cursor: pointer;
  padding: 0.25rem;
  font-size: 0.875rem;
}

.copy-btn:hover {
  color: #1d4ed8;
}

.citation-text {
  font-size: 0.75rem;
  color: #6b7280;
  background: #f9fafb;
  padding: 0.5rem;
  border-radius: 4px;
  line-height: 1.4;
}

/* Modal Styles */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  z-index: 1000;
}

.modal {
  background: white;
  border-radius: 12px;
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  max-width: 42rem;
  width: 100%;
  max-height: 90vh;
  overflow-y: auto;
}

.modal-content {
  padding: 1.5rem;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1.5rem;
}

.modal-title {
  font-size: 1.5rem;
  font-weight: bold;
  color: #1f2937;
}

.modal-close {
  background: none;
  border: none;
  color: #6b7280;
  cursor: pointer;
  font-size: 1.5rem;
  padding: 0.25rem;
}

.modal-close:hover {
  color: #1f2937;
}

/* Form Styles */
.form-group {
  margin-bottom: 1rem;
}

.form-label {
  display: block;
  font-size: 0.875rem;
  font-weight: 500;
  color: #374151;
  margin-bottom: 0.25rem;
}

.form-input {
  width: 100%;
  padding: 0.5rem 0.75rem;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  font-size: 0.875rem;
}

.form-input:focus {
  outline: none;
  border-color: #2563eb;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.2);
}

.form-textarea {
  width: 100%;
  padding: 0.5rem 0.75rem;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  font-size: 0.875rem;
  resize: vertical;
  min-height: 80px;
}

.form-textarea:focus {
  outline: none;
  border-color: #2563eb;
  box-shadow: 0 0 0 2px rgba(37, 99, 235, 0.2);
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
}
#footer-outer {
  margin-top: 15px;
}
@media (min-width: 768px) {
  .form-grid {
    grid-template-columns: 1fr 1fr;
  }
}

.form-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
  padding-top: 1rem;
}

.btn-secondary {
  padding: 0.5rem 1rem;
  color: #6b7280;
  border: 1px solid #d1d5db;
  background: white;
  border-radius: 8px;
  cursor: pointer;
  font-size: 0.875rem;
}

.btn-secondary:hover {
  background: #f9fafb;
}

.btn-primary {
  padding: 0.5rem 1rem;
  background: #2563eb;
  color: white;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
}

.btn-primary:hover {
  background: #1d4ed8;
}

.hidden {
  display: none;
}
#footer-outer {
  margin-top: 15px;
}
/* Responsive Design */
@media (max-width: 768px) {
  .paper-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }

  .paper-actions {
    align-self: flex-end;
  }

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

/* Dark Mode */

/* Dark Mode Styling */

body.dark-mode {
  background: linear-gradient(135deg, var(--bg-dark), #1f2937);
  color: #d1d5db;
}
body.dark-mode .add-btn {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
}

body.dark-mode .paper-card {
  background: #111827;
  border-color: #374151;
}
body.dark-mode .topic-badge {
  background: rgba(99, 102, 241, 0.25);
}

body.dark-mode .tag-badge {
  background: rgba(139, 152, 175, 0.15);
}

.dark-mode .header,
.dark-mode .search-bar,
.dark-mode .papers-section,
.dark-mode .details-section,
.dark-mode .modal {
  background: #1f2937;
  color: #d1d5db;
  box-shadow: 0 4px 6px -1px rgba(255, 255, 255, 0.05);
}

.dark-mode .header-title,
.dark-mode .details-title,
.dark-mode .modal-title,
.dark-mode .papers-title {
  color: #f3f4f6;
}

.dark-mode .header-subtitle,
.dark-mode .paper-authors,
.dark-mode .paper-meta,
.dark-mode .citation-style,
.dark-mode .citation-text,
.dark-mode .form-label,
.dark-mode .form-input,
.dark-mode .form-textarea {
  color: #9ca3af;
}

.dark-mode .add-btn,
.dark-mode .btn-primary {
  background: #3b82f6;
}

.dark-mode .add-btn:hover,
.dark-mode .btn-primary:hover {
  background: #2563eb;
}

.dark-mode .paper-card {
  border-color: #374151;
  background: #111827;
}

.dark-mode .paper-card:hover {
  border-color: #4b5563;
}

.dark-mode .paper-card.selected {
  background: #1e3a8a;
  border-color: #3b82f6;
}

.dark-mode .form-input,
.dark-mode .form-textarea,
.dark-mode .filter-select,
.dark-mode .search-input {
  background: #111827;
  border: 1px solid #374151;
  color: #e5e7eb;
}

.dark-mode .search-icon {
  color: #9ca3af;
}

.dark-mode .topic-badge {
  background: #1e3a8a;
  color: #bfdbfe;
}

.dark-mode .tag-badge,
.dark-mode .detail-tag {
  background: #374151;
  color: #d1d5db;
}

.dark-mode .citation-text {
  background: #111827;
  border: 1px solid #4b5563;
}

.dark-mode .btn-secondary {
  background: #111827;
  color: #9ca3af;
  border-color: #4b5563;
}

.dark-mode .btn-secondary:hover {
  background: #1f2937;
}

.dark-mode .modal {
  box-shadow: 0 20px 25px -5px rgba(255, 255, 255, 0.05);
}

.header-buttons {
  display: flex;
  align-items: center;
  gap: 10px;
}

/* Dark Mode Toggle Styling */
.dark-toggle {
  background: #f3f4f6;
  border: none;
  border-radius: 6px;
  padding: 8px 10px;
  font-size: 1rem;
  cursor: pointer;
  color: #1f2937;
  transition: background 0.3s ease;
}

.dark-toggle:hover {
  background: #e5e7eb;
}

/* Optional dark-mode override */
.dark-mode .dark-toggle {
  background: #374151;
  color: #d1d5db;
}

.dark-mode .dark-toggle:hover {
  background: #4b5563;
}

body.dark-mode .swal2-popup {
  background-color: #1f2937 !important;
  color: #f3f4f6 !important;
}

/* PDF Upload & Preview Styles */
.pdf-preview-container {
  margin-top: 1rem;
  display: flex;
  flex-direction: column;
}

.pdf-preview {
  width: 100%;
  height: 400px;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  margin-bottom: 0.5rem;
}

#clearPdfBtn {
  align-self: flex-start;
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
  background: #f3f4f6;
  border: 1px solid #d1d5db;
  color: #6b7280;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.2s;
}

#clearPdfBtn:hover {
  background: #e5e7eb;
}

/* Dark Mode adjustments for PDF preview */
body.dark-mode .pdf-preview {
  border: 1px solid #374151;
  background: #111827;
  color: #d1d5db;
}

body.dark-mode #clearPdfBtn {
  background: #1f2937;
  border-color: #4b5563;
  color: #9ca3af;
}

body.dark-mode #clearPdfBtn:hover {
  background: #374151;
}
.loading-spinner {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(255, 255, 255, 0.7);
  z-index: 9999;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.5rem;
  color: #333;
}

.hidden {
  display: none !important;
}
#footer-outer {
  margin-top: 15px;
}

.pagination-controls {
  margin-top: 1rem;
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  flex-wrap: wrap;
}

.pagination-controls button {
  padding: 6px 12px;
  border: 1px solid #ccc;
  background-color: white;
  cursor: pointer;
  border-radius: 4px;
}

.pagination-controls button:disabled {
  background-color: #f0f0f0;
  cursor: not-allowed;
  color: #888;
}

@media (max-width: 992px) {
  .header-content {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }

  .header-buttons {
    margin-top: 0.5rem;
    display: flex;
    width: 100%;
    justify-content: flex-start;
    gap: 0.5rem;
  }

  .main-grid {
    flex-direction: column;
  }

  .papers-section,
  .details-section {
    width: 100%;
  }

  .pdf-preview {
    height: 400px;
  }
  .search-content {
    display: flex;
    flex-direction: row;
    align-items: center;
    gap: 1rem;
    padding: 0.5rem 0;
  }

  .search-input-container,
  .filter-container {
    min-width: 130px;
    flex: 1 1 150px;
  }

  .search-input-container {
    flex: 2 1 300px;
  }

  .filter-container select,
  .filter-container input {
    width: 100%;
    min-width: 0;
  }
  #minYear,
  #maxYear {
    max-width: 90px;
    margin-right: 4px;
  }
}

@media (max-width: 600px) {
  body {
    font-size: 14px;
    padding: 0.5rem;
  }

  .header-title {
    font-size: 1.5rem;
  }

  .header-subtitle {
    font-size: 0.9rem;
  }

  .search-content {
    display: flex !important;
    flex-direction: column !important;
    align-items: stretch !important;
    gap: 0.75rem !important;
    padding: 0.5rem 0 !important;
  }

  .search-input-container,
  .filter-container {
    width: 100% !important;
    min-width: 0 !important;
    flex: none !important;
  }

  .filter-container:nth-child(3) {
    display: flex !important;
    gap: 0.5rem !important;
  }

  #minYear,
  #maxYear {
    flex: 1 !important;
    max-width: none !important;
    margin-right: 0 !important;
    width: 48% !important;
  }

  .search-input,
  .filter-select,
  input,
  select,
  textarea,
  button {
    width: 100% !important;
    font-size: 14px !important;
    padding: 0.75rem !important;
    box-sizing: border-box !important;
  }

  .container {
    padding: 0 0.75rem;
  }

  .header,
  .search-bar,
  .papers-section,
  .details-section {
    margin-bottom: 1rem;
    padding: 1rem;
  }

  .main-grid {
    gap: 1rem;
  }

  .form-grid {
    flex-direction: column;
  }

  .pdf-preview {
    height: 300px;
  }

  .modal {
    margin: 0.5rem;
    max-height: 95vh;
  }

  .modal-content {
    padding: 1rem;
  }

  .footer-inner {
    flex-direction: column;
    text-align: center;
    gap: 0.5rem;
  }

  .footer-social {
    justify-content: center;
    margin-top: 1rem;
  }

  .paper-card {
    padding: 0.75rem;
  }

  .paper-header {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }

  .paper-actions {
    align-self: flex-end;
    width: 100%;
    justify-content: flex-end;
  }

  .paper-title {
    font-size: 1rem;
    line-height: 1.4;
  }

  .details-grid {
    grid-template-columns: 1fr;
  }
}
@media (max-width: 400px) {
  .header-title i {
    display: none;
  }

  .btn-primary,
  .btn-secondary {
    width: 100%;
  }

  .pdf-preview {
    height: 220px;
  }

  .filter-container:nth-child(3) {
    flex-direction: column !important;
    gap: 0.5rem !important;
  }

  #minYear,
  #maxYear {
    width: 100% !important;
  }

  body {
    padding: 0.25rem;
  }

  .container {
    padding: 0 0.5rem;
  }

  .header,
  .search-bar,
  .papers-section,
  .details-section {
    padding: 0.75rem;
  }
}



/* User Menu Styles */
.user-menu {
  position: relative;
  margin-right: 0.5rem;
}

.user-btn {
  background: #f3f4f6;
  border: none;
  border-radius: 8px;
  padding: 0.5rem 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: #1f2937;
  transition: background-color 0.2s;
}

.user-btn:hover {
  background: #e5e7eb;
}

.user-dropdown {
  position: absolute;
  top: 100%;
  right: 0;
  background: white;
  border: 1px solid #e5e7eb;
  border-radius: 8px;
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  min-width: 200px;
  z-index: 1000;
  margin-top: 0.5rem;
}

.user-info {
  padding: 1rem;
  text-align: left;
}

.user-info strong {
  display: block;
  color: #1f2937;
  margin-bottom: 0.25rem;
}

.user-info small {
  color: #6b7280;
  font-size: 0.75rem;
}

.user-dropdown hr {
  border: none;
  border-top: 1px solid #e5e7eb;
  margin: 0;
}

.logout-btn {
  width: 100%;
  background: none;
  border: none;
  padding: 0.75rem 1rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: #dc2626;
  transition: background-color 0.2s;
  text-align: left;
}

.logout-btn:hover {
  background: #fef2f2;
}

/* Dark mode user menu */
body.dark-mode .user-btn {
  background: #374151;
  color: #d1d5db;
}

body.dark-mode .user-btn:hover {
  background: #4b5563;
}

body.dark-mode .user-dropdown {
  background: #1f2937;
  border-color: #4b5563;
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
}

body.dark-mode .user-info strong {
  color: #f3f4f6;
}

body.dark-mode .user-info small {
  color: #9ca3af;
}

body.dark-mode .user-dropdown hr {
  border-color: #4b5563;
}

body.dark-mode .logout-btn:hover {
  background: #374151;
}



.favorite-btn.active {
  color: var(--accent);
}


/*=====back to top button====*/
/* Back to Top Button Styling */
#backToTop {
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 99;
  background-color: #6cb3fa;
  color: white;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 12px 15px;
  border-radius: 50%;
  font-size: 18px;
  display: none;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
  transition: transform 0.3s ease, background-color 0.3s ease;
}

/* Hover animation */
#backToTop:hover {
  background-color: #1e5a9e;
  transform: scale(1.1);
}

/* Responsive adjustments */
@media (max-width: 768px) {
  #backToTop {
    bottom: 15px;
    right: 15px;
    padding: 10px 12px;
    font-size: 16px;
  }
}

/* Rating and Favorite Form Styles */
.rating-container {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.stars-rating {
  display: flex;
  gap: 0.25rem;
  font-size: 1.8rem;
  cursor: pointer;
  padding: 0.5rem 0;
}

.star {
  color: #d1d5db;
  transition: color 0.2s ease;
  user-select: none;
  cursor: pointer;
  padding: 0.25rem;
  border-radius: 4px;
}

.star:hover,
.star.active {
  color: #fbbf24;
  transform: scale(1.1);
}

.star.hover {
  color: #fbbf24;
}

.favorite-container {
  display: flex;
  align-items: center;
}

.favorite-checkbox {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
  user-select: none;
}

.favorite-checkbox input[type="checkbox"] {
  display: none;
}

.favorite-icon {
  font-size: 1.25rem;
  color: #d1d5db;
  transition: color 0.2s ease;
}

.favorite-checkbox input[type="checkbox"]:checked + .favorite-icon {
  color: #ef4444;
}

.favorite-text {
  font-size: 0.875rem;
  color: var(--gray);
}

/* Paper Card Rating and Favorite Display */
.paper-rating {
  display: flex;
  align-items: center;
  gap: 0.25rem;
  font-size: 0.875rem;
}

.paper-rating .stars {
  color: #fbbf24;
}

.paper-rating .rating-text {
  color: var(--gray);
  font-size: 0.75rem;
}

.paper-favorite {
  color: #ef4444;
  font-size: 1rem;
}

.paper-meta-extended {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 0.5rem;
  padding-top: 0.5rem;
  border-top: 1px solid #e5e7eb;
}

.rating-favorite-row {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Dark mode adjustments */
body.dark-mode .star.active,
body.dark-mode .star.hover,
body.dark-mode .paper-rating .stars {
  color: #fbbf24;
}

body.dark-mode .favorite-checkbox input[type="checkbox"]:checked + .favorite-icon,
body.dark-mode .paper-favorite {
  color: #ef4444;
}

body.dark-mode .paper-meta-extended {
  border-top-color: #374151;
}

body.dark-mode .favorite-text {
  color: #9ca3af;
}

body.dark-mode .paper-rating .rating-text {
  color: #9ca3af;
}

/* Quick Rating Stars on Paper Cards */
.paper-quick-rating {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-top: 0.75rem;
  padding: 0.5rem;
  background-color: #f9fafb;
  border-radius: 6px;
  border: 1px solid #e5e7eb;
}

.rating-label {
  font-size: 0.75rem;
  font-weight: 500;
  color: #6b7280;
  min-width: 35px;
}

.quick-stars {
  display: flex;
  gap: 0.125rem;
}

.quick-star {
  font-size: 1.2rem;
  color: #d1d5db;
  cursor: pointer;
  transition: all 0.2s ease;
  padding: 0.125rem;
  border-radius: 3px;
  user-select: none;
}

.quick-star:hover {
  color: #fbbf24;
  transform: scale(1.1);
}

.quick-star.active {
  color: #fbbf24;
}

.current-rating {
  font-size: 0.75rem;
  color: #6b7280;
  margin-left: 0.25rem;
}

/* Dark mode for quick rating */
body.dark-mode .paper-quick-rating {
  background-color: #374151;
  border-color: #4b5563;
}

body.dark-mode .rating-label,
body.dark-mode .current-rating {
  color: #9ca3af;
}

body.dark-mode .quick-star {
  color: #6b7280;
}

body.dark-mode .quick-star:hover,
body.dark-mode .quick-star.active {
  color: #fbbf24;
}

/* Paper card transition for rating feedback */
.paper-card {
  transition: transform 0.2s ease;
}

/* Rating and Favorite Details Display */
.rating-favorite-details {
  display: flex;
  gap: 2rem;
  align-items: center;
  flex-wrap: wrap;
}

.rating-display,
.favorite-display {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.rating-display .paper-rating {
  margin: 0;
}

.favorite-display .paper-favorite {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}

@media (max-width: 768px) {
  .rating-favorite-details {
    flex-direction: column;
    align-items: flex-start;
    gap: 1rem;

  }
}

/* Chatbot Toggle Button */
#chatbot-toggle {
  position: fixed;
  bottom: 90px; /* sits above Back-to-Top which is bottom:20px */
  right: 20px;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  border: none;
  outline: none;
  cursor: pointer;
  padding: 14px 16px;
  border-radius: 50%;
  font-size: 20px;
  z-index: 10001;
  box-shadow: 0 4px 10px rgba(0,0,0,0.2);
  transition: transform 0.3s ease, background-color 0.3s ease;
}

#chatbot-toggle:hover {
  background: #1e40af;
  transform: scale(1.1);
}

/* Chatbot Window */
#chatbot-container {
  position: fixed;
  bottom: 160px; /* above toggle button */
  right: 20px;
  width: 320px;
  max-height: 430px;
  background: white;
  border-radius: 12px;
  box-shadow: 0 8px 20px rgba(0,0,0,0.2);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  z-index: 10000;
}

.chatbot-header {
  background: var(--primary);
  color: white;
  padding: 10px 12px;
  font-weight: 600;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.chatbot-header button {
  background: none;
  border: none;
  color: white;
  font-size: 18px;
  cursor: pointer;
}

.chatbot-messages {
  flex: 1;
  padding: 10px;
  overflow-y: auto;
  font-size: 14px;
  background: #f9fafb;
}

.chatbot-message {
  margin-bottom: 10px;
  max-width: 85%;
  line-height: 1.35;
  padding: 8px 10px;
  border-radius: 10px;
  word-wrap: break-word;
}

.chatbot-message.user {
  margin-left: auto;
  background: #e0e7ff;
  color: #1e3a8a;
}

.chatbot-message.bot {
  margin-right: auto;
  background: #ffffff;
  color: #374151;
  border: 1px solid #e5e7eb;
}

.chatbot-input-container {
  display: flex;
  border-top: 1px solid #e5e7eb;
  background: #ffffff;
}

.chatbot-input-container input {
  flex: 1;
  padding: 10px;
  border: none;
  outline: none;
  font-size: 14px;
  background: transparent;
}

.chatbot-input-container button {
  background: var(--primary);
  color: white;
  border: none;
  padding: 0 14px;
  cursor: pointer;
  font-size: 16px;
  border-top-left-radius: 8px;
}

/* Typing Indicator */
.chatbot-typing {
  display: inline-block;
  width: 6px;
  height: 6px;
  margin: 0 2px;
  background: #9ca3af;
  border-radius: 50%;
  animation: blink 1.2s infinite;
}

.chatbot-typing:nth-child(2) { animation-delay: 0.2s; }
.chatbot-typing:nth-child(3) { animation-delay: 0.4s; }

@keyframes blink {
  0% { opacity: 0.25; }
  50% { opacity: 1; }
  100% { opacity: 0.25; }
}

/* Dark mode */
body.dark-mode #chatbot-container {
  background: var(--bg-dark);
  color: var(--text-light);
  box-shadow: 0 8px 20px rgba(0,0,0,0.6);
}

body.dark-mode .chatbot-header {
  background: var(--primary-dark);
}

body.dark-mode .chatbot-messages {
  background: #111827;
}

body.dark-mode .chatbot-message.bot {
  background: #1f2937;
  color: var(--text-light);
  border-color: #374151;
}

body.dark-mode .chatbot-message.user {
  background: #1e3a8a;
  color: #dbeafe;
}

body.dark-mode .chatbot-input-container {
  background: #1f2937;
  border-top-color: #374151;
}

@media (max-width: 480px) {
  #chatbot-container {
    width: calc(100% - 24px);
    right: 12px;
    bottom: 120px;
    max-height: 60vh;
  }
}