:root {
  --ink: #10232e;
  --ink-soft: #3d5462;
  --teal: #0e6e6a;
  --teal-dark: #0a504d;
  --teal-soft: #e3f1f0;
  --amber: #b4690e;
  --amber-soft: #fdf1e2;
  --violet: #5b4b8a;
  --violet-soft: #edeaf6;
  --paper: #f7f9f9;
  --card: #ffffff;
  --line: #dbe4e6;
  --radius: 12px;
  --shadow: 0 1px 3px rgba(16, 35, 46, 0.08), 0 4px 16px rgba(16, 35, 46, 0.06);
  --font-body: "Inter", system-ui, -apple-system, sans-serif;
  --font-display: "Source Serif 4", Georgia, serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 1060px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  background: var(--ink);
  color: #fff;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 14px;
  padding-bottom: 14px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
  color: inherit;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 42px;
  height: 42px;
  border-radius: 10px;
  background: var(--teal);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
}

.brand-text { display: flex; flex-direction: column; }
.brand-name { font-family: var(--font-display); font-weight: 700; font-size: 1.05rem; line-height: 1.2; }
.brand-domain { font-size: 0.75rem; color: #9db4bd; }

.header-tag {
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: #9db4bd;
  border: 1px solid #33505e;
  border-radius: 999px;
  padding: 5px 12px;
}

/* Hero */
.hero { padding: 44px 0 8px; max-width: 760px; }

.hero h1 {
  font-family: var(--font-display);
  font-size: 2.4rem;
  margin: 0 0 10px;
  letter-spacing: -0.01em;
}

.lede { color: var(--ink-soft); font-size: 1.02rem; margin: 0; }

/* Drop zones */
.dropzones {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
  margin-top: 28px;
}

.group-panel {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px;
  display: flex;
  flex-direction: column;
}

.group-head {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 12px;
}

.group-badge {
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 8px;
  color: #fff;
  font-weight: 700;
  font-size: 0.9rem;
  flex-shrink: 0;
}

.badge-a { background: var(--teal); }
.badge-b { background: var(--amber); }

.group-name {
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 1rem;
  color: var(--ink);
  border: 1px solid transparent;
  border-radius: 6px;
  padding: 4px 8px;
  flex: 1;
  min-width: 0;
  background: transparent;
}

.group-name:hover { border-color: var(--line); }
.group-name:focus { outline: none; border-color: var(--teal); background: #fff; }

.clear-btn {
  border: none;
  background: none;
  color: var(--ink-soft);
  font-size: 0.8rem;
  font-weight: 500;
  cursor: pointer;
  padding: 4px 8px;
  border-radius: 6px;
}

.clear-btn:hover { background: #f0eded; color: #a33; }

.dropzone {
  border: 2px dashed var(--line);
  border-radius: 10px;
  padding: 30px 16px;
  text-align: center;
  color: var(--ink-soft);
  cursor: pointer;
  transition: border-color 0.15s, background-color 0.15s;
}

.dropzone:hover, .dropzone:focus-visible { border-color: var(--teal); background: var(--teal-soft); outline: none; }
.dropzone.dragover { border-color: var(--teal); background: var(--teal-soft); border-style: solid; }

#panel-b .dropzone:hover, #panel-b .dropzone:focus-visible, #panel-b .dropzone.dragover {
  border-color: var(--amber);
  background: var(--amber-soft);
}

.dz-icon { width: 30px; height: 30px; margin-bottom: 6px; opacity: 0.6; }
.dz-title { margin: 0; font-weight: 600; color: var(--ink); }
.dz-sub { margin: 4px 0 0; font-size: 0.85rem; }

.file-list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.file-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: 8px;
  padding: 7px 10px;
}

.file-list .fname {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-weight: 500;
}

.file-list .frecs { color: var(--ink-soft); font-size: 0.78rem; flex-shrink: 0; }

.file-list .fremove {
  border: none;
  background: none;
  color: var(--ink-soft);
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  padding: 2px 5px;
  border-radius: 4px;
  flex-shrink: 0;
}

.file-list .fremove:hover { background: #f0eded; color: #a33; }

.group-count {
  margin: 10px 0 0;
  font-size: 0.85rem;
  color: var(--ink-soft);
}

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

/* Matching note */
.matching-note {
  margin-top: 18px;
  font-size: 0.85rem;
  color: var(--ink-soft);
  background: var(--card);
  border: 1px solid var(--line);
  border-left: 3px solid var(--teal);
  border-radius: 8px;
  padding: 10px 14px;
}

/* Results */
.results { margin-top: 34px; }

.summary {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 16px;
}

.stat {
  font-family: var(--font-body);
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 18px 16px 14px;
  text-align: center;
  cursor: pointer;
  transition: transform 0.1s, border-color 0.15s;
  border-top: 4px solid var(--line);
}

.stat:hover { transform: translateY(-1px); }
.stat-a { border-top-color: var(--teal); }
.stat-both { border-top-color: var(--violet); }
.stat-b { border-top-color: var(--amber); }

.stat-num {
  display: block;
  font-family: var(--font-display);
  font-size: 2.1rem;
  font-weight: 700;
  line-height: 1.1;
}

.stat-a .stat-num { color: var(--teal-dark); }
.stat-both .stat-num { color: var(--violet); }
.stat-b .stat-num { color: var(--amber); }

.stat-label { font-size: 0.82rem; color: var(--ink-soft); font-weight: 500; }

.results-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  margin-top: 24px;
  flex-wrap: wrap;
}

.tabs {
  display: flex;
  gap: 4px;
  background: #e8eef0;
  border-radius: 10px;
  padding: 4px;
}

.tab {
  border: none;
  background: none;
  font-family: var(--font-body);
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--ink-soft);
  padding: 7px 16px;
  border-radius: 7px;
  cursor: pointer;
}

.tab.active { background: #fff; color: var(--ink); box-shadow: 0 1px 3px rgba(16,35,46,0.12); }

.export-menu { display: flex; gap: 8px; }

.btn {
  font-family: var(--font-body);
  font-size: 0.88rem;
  font-weight: 600;
  border: 1px solid var(--line);
  background: var(--card);
  color: var(--ink);
  border-radius: 8px;
  padding: 8px 16px;
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s;
}

.btn:hover { border-color: var(--teal); color: var(--teal-dark); }

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

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

/* Table */
.table-wrap {
  margin-top: 16px;
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow-x: auto;
}

.ref-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
}

.ref-table th {
  text-align: left;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--ink-soft);
  background: var(--paper);
  padding: 10px 14px;
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}

.ref-table td {
  padding: 11px 14px;
  border-bottom: 1px solid #eef2f3;
  vertical-align: top;
}

.ref-table tr:last-child td { border-bottom: none; }
.ref-table tbody tr:hover { background: #fafcfc; }

.col-n { width: 42px; color: var(--ink-soft); }
.col-year { width: 60px; white-space: nowrap; }
.col-doi { width: 190px; }
.col-match { width: 90px; }

.ref-title { font-weight: 600; display: block; }
.ref-meta { color: var(--ink-soft); font-size: 0.82rem; display: block; margin-top: 2px; }

.doi-link {
  color: var(--teal-dark);
  text-decoration: none;
  word-break: break-all;
  font-size: 0.8rem;
}

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

.match-pill {
  display: inline-block;
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 2px 8px;
  border-radius: 999px;
}

.match-doi { background: var(--teal-soft); color: var(--teal-dark); }
.match-title { background: var(--violet-soft); color: var(--violet); }
.match-none { background: #eef2f3; color: var(--ink-soft); }

.empty-msg { text-align: center; color: var(--ink-soft); padding: 30px 0; margin: 0; }

/* Privacy note */
.privacy-note {
  margin: 30px 0 50px;
  font-size: 0.85rem;
  color: var(--ink-soft);
  text-align: center;
}

/* Footer */
.site-footer {
  background: var(--ink);
  color: #9db4bd;
  padding: 26px 0;
  font-size: 0.85rem;
}

.footer-inner p { margin: 0 0 4px; }
.footer-inner a { color: #fff; text-decoration: none; font-weight: 600; }
.footer-inner a:hover { text-decoration: underline; }
.footer-sub { font-size: 0.78rem; }

/* Responsive */
@media (max-width: 720px) {
  .dropzones, .summary { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.9rem; }
  .results-toolbar { flex-direction: column; align-items: stretch; }
  .export-menu { justify-content: stretch; }
  .export-menu .btn { flex: 1; }
}