:root {
  --bg-color: #ffffff;
  --text-color: #000000;
  --text-secondary: #666666;
  --accent-color: #333333;
  --card-bg: #ffffff;
  --border-color: #ddd;
  --hover-bg: #f5f5f5;
  --bg-secondary: #f9f9f9;

  --font-heading: 'Outfit', sans-serif;
  --font-body: 'Inter', sans-serif;
}

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

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  font-family: var(--font-body);
  min-height: 100vh;
  line-height: 1.6;
}

#app {
  max-width: 1000px;
  margin: 0 auto;
  padding: 4rem 2rem;
}

/* Header */
header {
  margin-bottom: 2rem;
}

h1 {
  font-family: var(--font-heading);
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 0;
  color: #111;
}

header p {
  color: var(--text-secondary);
  font-size: 1.2rem;
  margin-top: 0.5rem;
  font-weight: 400;
}

/* Search & Upload Section */
.search-section {
  max-width: 700px;
  margin: 0 auto 2rem;
}


.upload-box {
  border: 1px solid var(--border-color);
  padding: 1rem 1.5rem;
  background: var(--bg-secondary);
  transition: all 0.2s;
}

.upload-box:hover,
.upload-box.drag-over {
  background: var(--hover-bg);
  border-color: var(--text-color);
}

.upload-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}

.upload-row .upload-icon {
  font-size: 1.25rem;
}

.upload-row span {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.upload-row strong {
  color: var(--text-color);
}

.file-btn-inline {
  background: var(--text-color);
  color: var(--bg-color);
  padding: 0.4rem 0.8rem;
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s;
}

.file-btn-inline:hover {
  background: var(--accent-color);
}

.file-btn-inline input[type="file"] {
  display: none;
}

.url-row {
  display: flex;
  gap: 0.5rem;
}

.url-row input[type="url"] {
  flex: 1;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border-color);
  font-size: 0.85rem;
  font-family: var(--font-body);
  background: var(--bg-color);
}

.url-row input[type="url"]:focus {
  outline: none;
  border-color: var(--text-color);
}

.btn-load {
  background: var(--hover-bg);
  color: var(--text-color);
  border: 1px solid var(--border-color);
  padding: 0.5rem 1rem;
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 500;
  font-family: var(--font-body);
  transition: all 0.2s;
}

.btn-load:hover {
  background: var(--text-color);
  color: var(--bg-color);
}

/* Filters */
.filters {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin-top: 2rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border-color);
}

.search-filter {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.search-filter input[type="search"] {
  width: 100%;
  padding: 0.75rem 1rem;
  font-size: 1rem;
  border: 1px solid var(--border-color);
  font-family: var(--font-body);
  background: var(--bg-color);
}

.search-filter input[type="search"]:focus {
  outline: none;
  border-color: var(--text-color);
}

.search-count {
  font-size: 0.85rem;
  color: var(--text-secondary);
  text-align: right;
}

.filter-actions {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
  flex-wrap: wrap;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.filter-group label {
  font-weight: 500;
  color: var(--text-secondary);
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.embed-link {
  color: var(--text-secondary);
  font-size: 0.85rem;
  text-decoration: none;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  transition: all 0.2s;
}

.embed-link:hover {
  color: var(--text-color);
  border-color: var(--text-color);
  background: var(--hover-bg);
}

/* Group Toggle & Checkbox */
.group-toggle,
.checkbox-group {
  display: flex;
  background: var(--bg-secondary);
  padding: 0.25rem;
  border: 1px solid var(--border-color);
  border-radius: 6px;
  gap: 0.25rem;
}

.group-btn,
.checkbox-btn {
  background: none;
  border: none;
  padding: 0.5rem 1rem;
  cursor: pointer;
  font-family: var(--font-body);
  font-size: 0.9rem;
  color: var(--text-secondary);
  border-radius: 4px;
  transition: all 0.2s;
}

.group-btn:hover,
.checkbox-btn:hover {
  color: var(--text-color);
}

.group-btn.active {
  background: var(--bg-color);
  color: var(--text-color);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
  font-weight: 500;
}

.checkbox-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  cursor: pointer;
}

.checkbox-btn input {
  accent-color: var(--text-color);
}

.group-toggle {
  display: flex;
  border: 1px solid var(--border-color);
}

.group-btn {
  padding: 0.5rem 1rem;
  background: var(--bg-color);
  border: none;
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
  font-family: var(--font-body);
}

.group-btn:first-child {
  border-right: 1px solid var(--border-color);
}

.group-btn:hover {
  background: var(--hover-bg);
}

.group-btn.active {
  background: var(--text-color);
  color: var(--bg-color);
}

.export-dropdown select {
  padding: 0.5rem 2rem 0.5rem 1rem;
  font-size: 0.9rem;
  font-weight: 500;
  border: 1px solid var(--border-color);
  background: var(--bg-color);
  color: var(--text-color);
  cursor: pointer;
  font-family: var(--font-body);
  appearance: none;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' fill='none' viewBox='0 0 24 24' stroke='%23000'%3E%3Cpath stroke-linecap='round' stroke-linejoin='round' stroke-width='2' d='M19 9l-7 7-7-7'%3E%3C/path%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.5rem center;
  background-size: 1rem;
}

.export-dropdown select:hover {
  background-color: var(--hover-bg);
}

.export-dropdown select:focus {
  outline: none;
  border-color: var(--text-color);
}

/* Button */
.btn-secondary {
  background: var(--hover-bg);
  color: var(--text-color);
  border: 1px solid var(--border-color);
  padding: 0.75rem 1.5rem;
  cursor: pointer;
  font-size: 0.95rem;
  font-weight: 500;
  transition: all 0.2s;
  font-family: var(--font-body);
}

.btn-secondary:hover {
  background: var(--text-color);
  color: var(--bg-color);
}

/* Stats Section */
.stats-section {
  margin-bottom: 3rem;
}

.stats-card {
  padding: 2rem;
}

.stats-grid {
  display: flex;
  justify-content: center;
  gap: 4rem;
}

.stats-grid .stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  border-bottom: none;
  padding: 0;
}

.stats-grid .stat-count {
  font-family: var(--font-heading);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-color);
}

.stats-grid .stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Cards */
.card {
  background: var(--bg-color);
  border: 1px solid var(--border-color);
  padding: 2rem;
  transition: all 0.2s ease;
}

.card:hover {
  border-color: var(--text-color);
  transform: translateY(-2px);
  box-shadow: 4px 4px 0 rgba(0, 0, 0, 0.05);
}

.card h2 {
  margin: 0 0 0.25rem;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-color);
}

/* Results Container */
.results-container {
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* Year/Type Groups */
.year-group {
  animation: fadeIn 0.5s ease-out;
}

.year-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.75rem;
  padding-bottom: 0.25rem;
  border-bottom: 2px solid #333;
}

.year-badge {
  font-family: var(--font-heading);
  font-size: 1.1rem;
  font-weight: 600;
  color: #111;
}

.year-count {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.year-publications {
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* Publication Cards */
.pub-card {
  background: transparent;
  border: none;
  border-bottom: 1px solid #eee;
  padding: 0.75rem 0;
  display: block;
}

.pub-card:last-child {
  border-bottom: none;
}

.pub-card:hover {
  background: transparent;
  transform: none;
}

.pub-type-indicator {
  width: 4px;
  flex-shrink: 0;
  background: var(--border-color);
}

.pub-type-indicator.conference {
  background: #333;
}

.pub-type-indicator.article {
  background: #666;
}

.pub-type-indicator.preprint {
  background: #999;
}

.pub-content {
  flex: 1;
  min-width: 0;
}

.pub-title {
  font-family: inherit;
  font-size: 1rem;
  font-weight: 500;
  margin: 0 0 0.25rem;
  line-height: 1.5;
  color: #000;
}

.pub-title a {
  color: inherit;
  text-decoration: none;
}

.pub-title a:hover {
  text-decoration: underline;
}

.pub-authors {
  color: #555;
  font-size: 0.9em;
  margin-bottom: 0.25rem;
}

.pub-venue {
  color: #666;
  font-size: 0.85em;
  font-style: italic;
}

.pub-type-badge {
  display: inline-block;
  background: var(--hover-bg);
  color: var(--text-secondary);
  padding: 0.15em 0.4em;
  font-size: 0.7em;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  border-radius: 3px;
  margin-left: 0.5rem;
  vertical-align: middle;
}

.pub-venue span {
  color: var(--text-secondary);
}

.pub-awards {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin-top: 0.25rem;
}

.pub-award {
  display: inline-block;
  font-size: 0.8em;
  color: #856404;
  background: #fff3cd;
  padding: 0.15em 0.5em;
  border-radius: 3px;
  font-weight: 500;
}

.pub-links {
  display: flex;
  gap: 0.75rem;
  margin-top: 0.25rem;
}

.pub-link {
  display: inline-block;
  font-size: 0.8em;
  color: #0066cc;
  text-decoration: none;
}

.pub-link:hover {
  text-decoration: underline;
}



/* Footer */
footer {
  margin-top: 4rem;
  padding: 2rem 0;
  text-align: center;
  border-top: 1px solid var(--border-color);
}

footer a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s;
}

footer a:hover {
  color: var(--text-color);
  text-decoration: underline;
}

/* Modal/Loading */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.25);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 1000;
  backdrop-filter: blur(8px);
  opacity: 1;
  transition: opacity 0.5s ease;
}

.modal.hidden {
  opacity: 0;
  pointer-events: none;
}

.modal-content {
  background: #ffffff;
  border-radius: 24px;
  box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.15);
  border: 1px solid rgba(0, 0, 0, 0.05);
}

.spinner {
  display: inline-block;
  font-size: 2rem;
  animation: spin 1s linear infinite;
}

@keyframes spin {
  from {
    transform: rotate(0deg);
  }

  to {
    transform: rotate(360deg);
  }
}

.bibtex-modal-content {
  max-width: 800px;
  width: 90%;
  padding: 2rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}

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

.modal-header h3 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: 1.5rem;
}

.close-btn {
  background: none;
  border: none;
  font-size: 2rem;
  cursor: pointer;
  color: var(--text-secondary);
  line-height: 1;
}

.close-btn:hover {
  color: var(--text-color);
}

#bibtexContent {
  background: var(--bg-secondary);
  padding: 1.5rem;
  border-radius: 12px;
  font-family: 'Courier New', Courier, monospace;
  font-size: 0.9rem;
  white-space: pre-wrap;
  word-break: break-all;
  overflow-y: auto;
  max-height: 400px;
  border: 1px solid var(--border-color);
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
}

.btn-primary {
  background: var(--text-color);
  color: var(--bg-color);
  border: none;
  padding: 0.8rem 1.5rem;
  border-radius: 8px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s;
}

.btn-primary:hover {
  opacity: 0.9;
}

/* Animations */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(10px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 4rem 2rem;
  color: var(--text-secondary);
}

.empty-icon {
  font-size: 3rem;
  display: block;
  margin-bottom: 1rem;
}

/* Responsive */
@media (max-width: 768px) {
  #app {
    padding: 2rem 1rem;
  }

  h1 {
    font-size: 2.5rem;
  }

  .stats-grid {
    gap: 2rem;
  }

  .stats-grid .stat-count {
    font-size: 2rem;
  }

  .pub-card {
    padding: 1rem;
  }

  .url-input-group {
    flex-direction: column;
  }
}