/* =====================================================
   Research Finder — Stylesheet
   Aesthetic: warm academic editorial, parchment tones
   Fonts: Fraunces (serif display) + DM Mono + DM Sans
   ===================================================== */

:root {
  --bg:           #f7f4ee;
  --bg-2:         #eeeae0;
  --surface:      #fffdf8;
  --surface-2:    #f2ede3;
  --border:       #ddd8cc;
  --border-dark:  #c8c2b4;
  --ink:          #1a1712;
  --ink-2:        #4a4540;
  --ink-3:        #8a8278;
  --accent:       #2d6a4f;
  --accent-light: #52b788;
  --accent-bg:    rgba(45, 106, 79, 0.08);
  --accent-border:rgba(45, 106, 79, 0.25);
  --red:          #c1440e;
  --red-bg:       rgba(193, 68, 14, 0.08);
  --gold:         #b5850a;
  --gold-bg:      rgba(181, 133, 10, 0.10);
  --shadow-sm:    0 1px 4px rgba(0,0,0,0.06);
  --shadow:       0 4px 20px rgba(0,0,0,0.08);
  --shadow-lg:    0 12px 48px rgba(0,0,0,0.14);
  --radius:       6px;
  --radius-lg:    12px;
  --radius-xl:    20px;
  --font-serif:   'Fraunces', Georgia, serif;
  --font-sans:    'DM Sans', system-ui, sans-serif;
  --font-mono:    'DM Mono', 'Courier New', monospace;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 15px;
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

::-webkit-scrollbar { width: 6px; }
::-webkit-scrollbar-track { background: var(--bg-2); }
::-webkit-scrollbar-thumb { background: var(--border-dark); border-radius: 3px; }

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── HEADER ─────────────────────────────────────────── */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(247, 244, 238, 0.95);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  gap: 28px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.logo-icon {
  font-size: 26px;
  color: var(--accent);
  line-height: 1;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.logo-main {
  font-family: var(--font-serif);
  font-weight: 600;
  font-size: 17px;
  color: var(--ink);
}

.logo-sub {
  font-size: 10px;
  color: var(--ink-3);
  letter-spacing: 0.03em;
}

/* ── TAB NAV ── */
.tab-nav {
  display: flex;
  gap: 4px;
  flex: 1;
}

.tab-btn {
  background: transparent;
  border: none;
  color: var(--ink-2);
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 500;
  padding: 7px 18px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.18s;
  display: flex;
  align-items: center;
  gap: 8px;
}

.tab-btn:hover { background: var(--surface-2); color: var(--ink); }

.tab-btn.active {
  background: var(--accent);
  color: #fff;
}

.library-count {
  background: rgba(255,255,255,0.25);
  color: #fff;
  font-size: 11px;
  font-weight: 600;
  padding: 1px 7px;
  border-radius: 20px;
  min-width: 20px;
  text-align: center;
}

.tab-btn:not(.active) .library-count {
  background: var(--accent-bg);
  color: var(--accent);
}

/* ── HEADER RIGHT ── */
.header-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.source-badge, .cache-badge {
  font-family: var(--font-mono);
  font-size: 10px;
  padding: 3px 8px;
  border-radius: 20px;
  border: 1px solid;
  display: none;
}

.source-badge.openalex {
  display: inline-block;
  color: var(--accent);
  border-color: var(--accent-border);
  background: var(--accent-bg);
}

.source-badge.crossref {
  display: inline-block;
  color: var(--gold);
  border-color: rgba(181,133,10,0.3);
  background: var(--gold-bg);
}

.cache-badge.cached {
  display: inline-block;
  color: var(--ink-3);
  border-color: var(--border-dark);
  background: var(--surface-2);
}

/* ── TOAST ── */
.toast {
  position: fixed;
  top: 76px;
  right: 24px;
  z-index: 999;
  padding: 12px 20px;
  border-radius: var(--radius);
  font-size: 13px;
  max-width: 360px;
  pointer-events: none;
  opacity: 0;
  transform: translateY(-8px);
  transition: all 0.25s;
  box-shadow: var(--shadow);
}

.toast.show { opacity: 1; transform: translateY(0); }

.toast.error {
  background: var(--red-bg);
  border: 1px solid var(--red);
  color: var(--red);
}

.toast.success {
  background: var(--accent-bg);
  border: 1px solid var(--accent-border);
  color: var(--accent);
}

/* ── MAIN ── */
.main {
  flex: 1;
  max-width: 1100px;
  width: 100%;
  margin: 0 auto;
  padding: 0 24px 48px;
}

/* ── TAB PANELS ── */
.tab-panel { display: none; }
.tab-panel.active { display: block; animation: fadeIn 0.22s ease; }

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── HERO ── */
.hero {
  padding: 52px 0 36px;
  max-width: 720px;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: 44px;
  font-weight: 600;
  letter-spacing: -0.02em;
  line-height: 1.1;
  color: var(--ink);
  margin-bottom: 10px;
}

.hero-sub {
  color: var(--ink-2);
  font-size: 16px;
  margin-bottom: 28px;
}

/* ── SEARCH BOX ── */
.search-box {
  display: flex;
  gap: 0;
  margin-bottom: 16px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  border: 1.5px solid var(--border-dark);
  background: var(--surface);
  box-shadow: var(--shadow);
  transition: border-color 0.18s, box-shadow 0.18s;
}

.search-box:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-bg), var(--shadow);
}

.search-input {
  flex: 1;
  border: none;
  outline: none;
  background: transparent;
  padding: 14px 20px;
  font-family: var(--font-sans);
  font-size: 16px;
  color: var(--ink);
}

.search-input::placeholder { color: var(--ink-3); }

.search-btn {
  background: var(--accent);
  border: none;
  color: #fff;
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 600;
  padding: 14px 28px;
  cursor: pointer;
  transition: background 0.18s;
  white-space: nowrap;
}

.search-btn:hover { background: #235c44; }

/* ── FILTERS ROW ── */
.filters-row {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  align-items: flex-end;
}

.filter-group {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.filter-label {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.filter-input, .filter-select {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 7px 10px;
  font-family: var(--font-sans);
  font-size: 13px;
  color: var(--ink);
  outline: none;
  transition: border-color 0.18s;
  min-width: 120px;
}

.filter-input:focus, .filter-select:focus {
  border-color: var(--accent);
}

/* ── OA TOGGLE ── */
.oa-toggle {
  display: flex;
  align-items: center;
  gap: 7px;
  cursor: pointer;
  padding-bottom: 2px;
}

.oa-toggle input[type="checkbox"] {
  width: 16px;
  height: 16px;
  accent-color: var(--accent);
  cursor: pointer;
}

.oa-label {
  font-size: 13px;
  color: var(--ink-2);
  user-select: none;
}

/* ── RESULTS META ── */
.results-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
  gap: 12px;
}

.results-count {
  font-size: 13px;
  color: var(--ink-2);
}

.results-count strong { color: var(--ink); }

/* ── PAGINATION ── */
.pagination {
  display: flex;
  gap: 6px;
  align-items: center;
}

.page-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--ink-2);
  font-family: var(--font-mono);
  font-size: 12px;
  padding: 5px 12px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.15s;
}

.page-btn:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
.page-btn.active { background: var(--accent); border-color: var(--accent); color: #fff; }
.page-btn:disabled { opacity: 0.35; cursor: default; }

/* ── PAPER CARDS ── */
.papers-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.paper-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 22px 24px;
  transition: box-shadow 0.18s, border-color 0.18s;
  position: relative;
}

.paper-card:hover {
  box-shadow: var(--shadow);
  border-color: var(--border-dark);
}

.paper-card-top {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: 8px;
}

.paper-title {
  font-family: var(--font-serif);
  font-size: 18px;
  font-weight: 600;
  line-height: 1.35;
  color: var(--ink);
  cursor: pointer;
  flex: 1;
}

.paper-title:hover { color: var(--accent); }

.paper-badges {
  display: flex;
  gap: 6px;
  flex-shrink: 0;
  flex-wrap: wrap;
  justify-content: flex-end;
}

.badge {
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 3px 8px;
  border-radius: 20px;
  border: 1px solid;
  white-space: nowrap;
}

.badge-oa {
  color: var(--accent);
  border-color: var(--accent-border);
  background: var(--accent-bg);
}

.badge-type {
  color: var(--ink-3);
  border-color: var(--border);
  background: var(--surface-2);
}

.badge-source-oa {
  color: var(--accent);
  border-color: var(--accent-border);
  background: var(--accent-bg);
}

.badge-source-cr {
  color: var(--gold);
  border-color: rgba(181,133,10,0.3);
  background: var(--gold-bg);
}

.paper-meta {
  font-size: 13px;
  color: var(--ink-2);
  margin-bottom: 10px;
  line-height: 1.5;
}

.paper-meta .authors {
  font-weight: 500;
  color: var(--ink);
}

.paper-meta .venue {
  font-style: italic;
}

.paper-abstract {
  font-size: 13px;
  color: var(--ink-2);
  line-height: 1.65;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
  margin-bottom: 14px;
}

.paper-concepts {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
  margin-bottom: 14px;
}

.concept-tag {
  font-size: 11px;
  padding: 2px 10px;
  border-radius: 20px;
  background: var(--surface-2);
  border: 1px solid var(--border);
  color: var(--ink-2);
}

.paper-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  padding-top: 12px;
  border-top: 1px solid var(--bg-2);
  flex-wrap: wrap;
}

.stat-chip {
  display: flex;
  align-items: center;
  gap: 4px;
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--ink-3);
}

.btn-sm {
  font-size: 12px;
  font-weight: 600;
  font-family: var(--font-sans);
  padding: 6px 14px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.15s;
  border: 1px solid;
}

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

.btn-primary:hover { background: #235c44; }

.btn-outline {
  background: transparent;
  border-color: var(--border-dark);
  color: var(--ink-2);
}

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.btn-outline.saved {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-bg);
}

.btn-outline.danger:hover {
  border-color: var(--red);
  color: var(--red);
}

.btn-link {
  background: none;
  border: none;
  font-size: 12px;
  color: var(--accent);
  cursor: pointer;
  padding: 6px 0;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.spacer { flex: 1; }

/* ── LOADING / EMPTY ── */
.loading-state {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--ink-2);
  font-size: 14px;
  padding: 48px 0;
}

.spinner {
  width: 20px;
  height: 20px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  flex-shrink: 0;
}

@keyframes spin { to { transform: rotate(360deg); } }

.empty-state {
  text-align: center;
  padding: 72px 0;
  color: var(--ink-3);
}

.empty-icon {
  font-size: 48px;
  margin-bottom: 16px;
  opacity: 0.4;
}

.library-empty {
  text-align: center;
  padding: 72px 0;
  color: var(--ink-3);
}

.library-empty .empty-icon { font-size: 48px; margin-bottom: 16px; }

.hidden { display: none !important; }

/* ── LIBRARY HEADER ── */
.library-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding: 40px 0 28px;
  gap: 16px;
  flex-wrap: wrap;
  border-bottom: 1px solid var(--border);
  margin-bottom: 24px;
}

.panel-title {
  font-family: var(--font-serif);
  font-size: 36px;
  font-weight: 600;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.panel-sub { font-size: 14px; color: var(--ink-2); margin-top: 4px; }

.library-actions {
  display: flex;
  gap: 10px;
  align-items: center;
}

/* ── MODAL ── */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(20, 17, 12, 0.55);
  z-index: 200;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  backdrop-filter: blur(4px);
  animation: fadeIn 0.2s ease;
}

.modal {
  background: var(--surface);
  border-radius: var(--radius-xl);
  max-width: 760px;
  width: 100%;
  max-height: 88vh;
  overflow-y: auto;
  box-shadow: var(--shadow-lg);
  position: relative;
  border: 1px solid var(--border);
}

.modal-close {
  position: sticky;
  top: 16px;
  float: right;
  margin: 16px 16px 0 0;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 32px;
  height: 32px;
  font-size: 14px;
  cursor: pointer;
  color: var(--ink-2);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s;
  z-index: 1;
}

.modal-close:hover { background: var(--red-bg); border-color: var(--red); color: var(--red); }

.modal-body { padding: 28px 32px 0; }

.modal-loading {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--ink-2);
  padding: 32px 0;
}

.modal-title {
  font-family: var(--font-serif);
  font-size: 24px;
  font-weight: 600;
  line-height: 1.3;
  color: var(--ink);
  margin-bottom: 12px;
}

.modal-authors {
  font-size: 14px;
  color: var(--ink-2);
  margin-bottom: 8px;
}

.modal-venue {
  font-size: 13px;
  font-style: italic;
  color: var(--ink-3);
  margin-bottom: 16px;
}

.modal-stats {
  display: flex;
  gap: 16px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.modal-stat {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.modal-stat-label {
  font-size: 10px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.modal-stat-val {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--ink);
}

.modal-abstract {
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-2);
  margin-bottom: 20px;
  padding: 16px 20px;
  background: var(--surface-2);
  border-radius: var(--radius);
  border-left: 3px solid var(--accent);
}

.modal-concepts {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.modal-links {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 24px;
}

/* ── CITATION PANEL ── */
.citation-panel {
  padding: 24px 32px 28px;
  border-top: 1px solid var(--border);
  background: var(--bg);
}

.citation-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 14px;
  flex-wrap: wrap;
  gap: 10px;
}

.citation-title {
  font-weight: 600;
  font-size: 14px;
  color: var(--ink);
}

.cite-format-btns {
  display: flex;
  gap: 4px;
  flex-wrap: wrap;
}

.cite-btn {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--ink-2);
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  padding: 4px 12px;
  border-radius: var(--radius);
  cursor: pointer;
  transition: all 0.15s;
}

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

.citation-output {
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.75;
  color: var(--ink-2);
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 16px;
  margin-bottom: 12px;
  white-space: pre-wrap;
  word-break: break-all;
  min-height: 60px;
}

/* ── FOOTER ── */
.footer {
  max-width: 1100px;
  margin: 0 auto;
  padding: 20px 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  font-size: 11px;
  color: var(--ink-3);
  border-top: 1px solid var(--border);
  flex-wrap: wrap;
}

.footer a { color: var(--ink-3); }
.footer a:hover { color: var(--accent); }

/* ── RESPONSIVE ── */
@media (max-width: 768px) {
  .hero-title { font-size: 32px; }
  .filters-row { gap: 8px; }
  .paper-card-top { flex-direction: column; }
  .paper-badges { justify-content: flex-start; }
  .modal-body { padding: 20px 20px 0; }
  .citation-panel { padding: 20px; }
  .library-header { flex-direction: column; }
  .header-inner { gap: 12px; }
  .logo-sub { display: none; }
}