/* ============================================================
   References Checker — Flat Design Stylesheet (Static Version)
   ============================================================ */

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

/* --- Custom Properties --- */
:root {
  --color-primary: #6366F1;
  --color-secondary: #818CF8;
  --color-cta: #10B981;
  --color-bg: #F5F3FF;
  --color-text: #1E1B4B;
  --color-warning: #F59E0B;
  --color-error: #EF4444;
  --color-card-bg: #FFFFFF;
  --color-muted: #475569;
  --font-heading: 'Crimson Pro', Georgia, serif;
  --font-body: 'Atkinson Hyperlegible', system-ui, sans-serif;
  --max-width: 1200px;
  --transition-speed: 180ms;
  --radius: 6px;
}

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

html {
  font-size: 100%;
  -webkit-text-size-adjust: 100%;
}

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

/* --- Typography --- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.25;
}

/* --- Focus ring --- */
:focus-visible {
  outline: 3px solid var(--color-primary);
  outline-offset: 2px;
}

/* --- Reduced motion --- */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* --- Container --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1rem;
  width: 100%;
}

/* ============================================================
   Header
   ============================================================ */
.app-header {
  padding: 2.5rem 0 1.5rem;
  text-align: center;
}

.app-header__back {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  color: var(--color-muted);
  font-size: 0.875rem;
  font-weight: 700;
  text-decoration: none;
  margin-bottom: 1rem;
  cursor: pointer;
  transition: color var(--transition-speed) ease;
}

.app-header__back:hover {
  color: var(--color-primary);
}

.app-header__back svg {
  width: 16px;
  height: 16px;
}

.app-header__title {
  font-size: 2.5rem;
  color: var(--color-primary);
  margin-bottom: 0.25rem;
}

.app-header__subtitle {
  font-size: 1.1rem;
  color: var(--color-muted);
  font-weight: 400;
}

/* ============================================================
   View toggling
   ============================================================ */
.view {
  display: none;
}

.view--active {
  display: block;
}

/* ============================================================
   Upload View
   ============================================================ */
.upload-section {
  max-width: 640px;
  margin: 2rem auto;
}

.drop-zone {
  position: relative;
  border: 3px dashed var(--color-secondary);
  border-radius: var(--radius);
  padding: 3rem 2rem;
  text-align: center;
  background: var(--color-card-bg);
  cursor: pointer;
  transition: border-color var(--transition-speed) ease,
              background-color var(--transition-speed) ease;
}

.drop-zone:hover,
.drop-zone--dragover {
  border-color: var(--color-primary);
  background: #EEF2FF;
}

.drop-zone__icon {
  display: block;
  margin: 0 auto 1rem;
  width: 48px;
  height: 48px;
  color: var(--color-secondary);
}

.drop-zone__text {
  font-size: 1.125rem;
  color: var(--color-text);
  margin-bottom: 0.5rem;
}

.drop-zone__hint {
  font-size: 0.875rem;
  color: var(--color-muted);
}

/* Hidden native file input */
.file-input {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

.upload-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  margin-top: 1.5rem;
  flex-wrap: wrap;
}

/* --- Buttons (shared) --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.75rem 1.5rem;
  font-family: var(--font-body);
  font-size: 1rem;
  font-weight: 700;
  border: 2px solid transparent;
  border-radius: var(--radius);
  cursor: pointer;
  transition: background-color var(--transition-speed) ease,
              color var(--transition-speed) ease,
              opacity var(--transition-speed) ease;
  text-decoration: none;
  line-height: 1;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

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

.btn--primary:hover:not(:disabled) {
  background: #4F46E5;
}

.btn--outline {
  background: transparent;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

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

.btn--cta {
  background: var(--color-cta);
  color: #FFFFFF;
}

.btn--cta:hover:not(:disabled) {
  background: #059669;
}

.btn--small {
  padding: 0.5rem 1rem;
  font-size: 0.875rem;
}

.btn svg {
  width: 18px;
  height: 18px;
  flex-shrink: 0;
}

/* Filter buttons */
.btn--filter {
  background: transparent;
  color: var(--color-muted);
  border-color: #D4D2E8;
}

.btn--filter:hover:not(:disabled) {
  background: #EEF2FF;
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.btn--filter--active {
  background: var(--color-primary);
  color: #FFFFFF;
  border-color: var(--color-primary);
}

.btn--filter--active:hover:not(:disabled) {
  background: #4F46E5;
  color: #FFFFFF;
}

.btn--filter svg {
  width: 14px;
  height: 14px;
}

.file-name-display {
  text-align: center;
  margin-top: 0.75rem;
  font-size: 0.9rem;
  color: var(--color-muted);
  min-height: 1.4em;
}

.upload-error {
  text-align: center;
  margin-top: 1rem;
  color: var(--color-error);
  font-weight: 700;
  min-height: 1.4em;
}

.upload-warning {
  text-align: center;
  margin-top: 0.75rem;
  color: var(--color-warning);
  font-weight: 700;
}

/* ============================================================
   Processing View
   ============================================================ */
.processing-section {
  max-width: 800px;
  margin: 2rem auto;
}

.progress-wrapper {
  margin-bottom: 1.5rem;
}

.progress-label {
  display: flex;
  justify-content: space-between;
  margin-bottom: 0.5rem;
  font-weight: 700;
  font-size: 0.95rem;
}

.progress-bar {
  width: 100%;
  height: 12px;
  background: #E2E0F5;
  border-radius: 6px;
  overflow: hidden;
}

.progress-bar__fill {
  height: 100%;
  width: 0%;
  background: var(--color-primary);
  border-radius: 6px;
  transition: width 300ms ease;
}

@keyframes progress-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}

.progress-bar__fill--active {
  animation: progress-pulse 1.5s ease-in-out infinite;
}

.progress-status {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--color-muted);
  text-align: center;
}

.live-feed {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

@media (max-width: 1024px) {
  .live-feed {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .live-feed {
    grid-template-columns: 1fr;
  }
}

/* ============================================================
   Result Cards (shared between live feed & results)
   ============================================================ */
.result-card {
  background: var(--color-card-bg);
  border-radius: var(--radius);
  position: relative;
  border-left: 5px solid var(--color-muted);
  padding: 1.25rem 1.5rem;
  transition: border-color var(--transition-speed) ease;
}

.result-card--found_pdf {
  border-left-color: var(--color-cta);
}

.result-card--found_abstract {
  border-left-color: var(--color-warning);
}

.result-card--not_found {
  border-left-color: var(--color-error);
}

.result-card--error {
  border-left-color: var(--color-error);
}

.result-card--insufficient_data {
  border-left-color: var(--color-muted);
}

.result-card__bib-key {
  display: inline-block;
  font-family: 'Courier New', Courier, monospace;
  font-size: 0.7rem;
  color: var(--color-muted);
  background: var(--color-bg);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  margin-bottom: 0.4rem;
  letter-spacing: 0.02em;
}

.result-card__header {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.result-card__status-icon {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  margin-top: 2px;
}

.result-card__status-icon--found_pdf {
  color: var(--color-cta);
}

.result-card__status-icon--found_abstract {
  color: var(--color-warning);
}

.result-card__status-icon--not_found,
.result-card__status-icon--error,
.result-card__status-icon--insufficient_data {
  color: var(--color-error);
}

.result-card__title {
  font-family: var(--font-heading);
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--color-text);
  flex: 1;
}

.result-card__meta {
  font-size: 0.875rem;
  color: var(--color-muted);
  margin-bottom: 0.5rem;
}

.result-card__meta span + span::before {
  content: ' \2022 ';
  margin: 0 0.25rem;
}

.result-card__badges {
  display: flex;
  flex-wrap: wrap;
  gap: 0.375rem;
  margin-bottom: 0.75rem;
}

/* Status badge */
.status-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem 0.6rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.status-badge svg {
  width: 14px;
  height: 14px;
}

.status-badge--found_pdf {
  background: #D1FAE5;
  color: #065F46;
}

.status-badge--found_abstract {
  background: #FEF3C7;
  color: #92400E;
}

.status-badge--not_found {
  background: #FEE2E2;
  color: #991B1B;
}

.status-badge--error {
  background: #FEE2E2;
  color: #991B1B;
}

.status-badge--insufficient_data {
  background: #E2E0F5;
  color: var(--color-muted);
}

/* Source badges */
.source-badge {
  display: inline-block;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 700;
  background: #E2E0F5;
  color: var(--color-primary);
  text-transform: lowercase;
}

/* Citation badge */
.citation-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.15rem 0.5rem;
  border-radius: 999px;
  font-size: 0.7rem;
  font-weight: 700;
  background: #DBEAFE;
  color: #1E40AF;
}

.citation-badge svg {
  width: 12px;
  height: 12px;
}

/* Abstract toggle */
.result-card__abstract-toggle {
  background: none;
  border: none;
  color: var(--color-primary);
  font-family: var(--font-body);
  font-size: 0.85rem;
  font-weight: 700;
  cursor: pointer;
  padding: 0.25rem 0;
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  transition: color var(--transition-speed) ease;
}

.result-card__abstract-toggle:hover {
  color: var(--color-text);
}

.result-card__abstract-toggle svg {
  width: 14px;
  height: 14px;
  transition: transform var(--transition-speed) ease;
}

.result-card__abstract-toggle--open svg {
  transform: rotate(180deg);
}

.result-card__abstract {
  display: none;
  margin-top: 0.5rem;
  padding: 0.75rem;
  background: var(--color-bg);
  border-radius: var(--radius);
  font-size: 0.875rem;
  line-height: 1.65;
  color: var(--color-muted);
}

.result-card__abstract--visible {
  display: block;
}

/* PDF link */
.result-card__pdf-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  margin-top: 0.5rem;
  color: var(--color-cta);
  font-size: 0.875rem;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  transition: color var(--transition-speed) ease;
}

.result-card__pdf-link:hover {
  color: #047857;
}

.result-card__pdf-link svg {
  width: 16px;
  height: 16px;
}

/* View online link */
.result-card__view-link {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  margin-top: 0.5rem;
  color: var(--color-primary);
  font-size: 0.875rem;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  transition: color var(--transition-speed) ease;
}

.result-card__view-link:hover {
  color: #4F46E5;
}

.result-card__view-link svg {
  width: 16px;
  height: 16px;
}

.result-card__error-msg {
  color: var(--color-error);
  font-size: 0.875rem;
  font-weight: 700;
}

.result-card__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.75rem;
  margin-top: 0.5rem;
}

/* ============================================================
   Results View
   ============================================================ */
.results-section {
  margin: 2rem auto;
}

/* Stats bar */
.stats-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  margin-bottom: 1.5rem;
  padding: 1.25rem;
  background: var(--color-card-bg);
  border-radius: var(--radius);
}

.stat-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  font-size: 1rem;
}

.stat-item svg {
  width: 20px;
  height: 20px;
}

.stat-item--total {
  color: var(--color-primary);
}

.stat-item--pdf {
  color: #065F46;
}

.stat-item--pdf svg {
  color: var(--color-cta);
}

.stat-item--abstract {
  color: #92400E;
}

.stat-item--abstract svg {
  color: var(--color-warning);
}

.stat-item--notfound {
  color: #991B1B;
}

.stat-item--notfound svg {
  color: var(--color-error);
}

/* Toolbar (search + filter + downloads) */
.results-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
  align-items: center;
  margin-bottom: 1.5rem;
}

.search-wrapper {
  flex: 1;
  min-width: 200px;
  position: relative;
}

.search-wrapper svg {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  width: 18px;
  height: 18px;
  color: var(--color-muted);
  pointer-events: none;
}

.search-input {
  width: 100%;
  padding: 0.7rem 0.75rem 0.7rem 2.5rem;
  font-family: var(--font-body);
  font-size: 0.95rem;
  border: 2px solid #D4D2E8;
  border-radius: var(--radius);
  background: var(--color-card-bg);
  color: var(--color-text);
  transition: border-color var(--transition-speed) ease;
}

.search-input::placeholder {
  color: var(--color-muted);
}

.search-input:focus {
  border-color: var(--color-primary);
  outline: none;
}

.filter-actions {
  display: flex;
  gap: 0.375rem;
  flex-wrap: wrap;
}

.download-actions {
  display: flex;
  gap: 0.5rem;
}

/* Results grid */
.results-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

@media (max-width: 1024px) {
  .results-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 640px) {
  .results-grid {
    grid-template-columns: 1fr;
  }
}

.no-results-msg {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--color-muted);
  font-size: 1.1rem;
}

/* Back / new check button */
.results-footer {
  text-align: center;
  margin-top: 2rem;
  padding-bottom: 3rem;
}

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

/* 768px - tablets */
@media (min-width: 768px) {
  .app-header__title {
    font-size: 3rem;
  }

  .drop-zone {
    padding: 4rem 3rem;
  }

  .stats-bar {
    gap: 2rem;
  }
}

/* 1024px */
@media (min-width: 1024px) {
  .container {
    padding: 0 2rem;
  }
}

/* 1440px */
@media (min-width: 1440px) {
  .container {
    padding: 0 2rem;
  }
}

/* ============================================================
   Utility
   ============================================================ */
.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;
}