:root {
  --bg: #f7f7f8; --panel: #ffffff; --panel2: #f3f4f6; --border: #e7e8ec;
  --fg: #1b1c1f; --dim: #6b7280; --muted: #9aa0aa;
  --accent: #f97316; --accent-d: #ea580c; --accent-soft: #fff2e8;
  --oa: #16a34a; --oa-soft: #e9f7ee; --chip: #f1f2f4; --radius: 12px;
  --shadow: 0 1px 2px rgba(16,24,40,.06), 0 1px 3px rgba(16,24,40,.05);
  --shadow-lg: 0 10px 30px rgba(16,24,40,.12);
}
* { box-sizing: border-box; -webkit-tap-highlight-color: transparent; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0; background: var(--bg); color: var(--fg);
  font: 16px/1.55 -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
a { color: var(--accent-d); text-decoration: none; }
a:hover { text-decoration: underline; }
.dim { color: var(--dim); }

/* ── header ───────────────────────────────────────────────────────────── */
header {
  display: flex; justify-content: space-between; align-items: center;
  padding: 16px 20px; gap: 14px; flex-wrap: wrap;
  background: var(--panel); border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 30;
}
.brand { display: flex; align-items: center; gap: 12px; }
.logo {
  font-size: 26px; width: 44px; height: 44px; display: grid; place-items: center;
  background: var(--accent-soft); border-radius: 12px;
}
h1 { margin: 0; font-size: 20px; letter-spacing: -.4px; font-weight: 700; }
h1 .dim { color: var(--accent); font-weight: 700; }
.tag { margin: 1px 0 0; color: var(--dim); font-size: 12.5px; }
.status { font-size: 12px; color: var(--dim); white-space: nowrap; }
.status .ok { color: var(--oa); font-weight: 600; }
.status .warn { color: var(--accent-d); font-weight: 600; }

/* ── search bar ───────────────────────────────────────────────────────── */
.searchbar { display: flex; gap: 10px; padding: 20px 20px 6px; max-width: 1180px; margin: 0 auto; width: 100%; }
#q {
  flex: 1; padding: 14px 16px; font-size: 16px; background: var(--panel);
  border: 1.5px solid var(--border); border-radius: var(--radius); color: var(--fg);
  outline: none; box-shadow: var(--shadow); transition: border-color .15s, box-shadow .15s;
}
#q::placeholder { color: var(--muted); }
#q:focus { border-color: var(--accent); box-shadow: 0 0 0 4px var(--accent-soft); }
#go {
  padding: 0 26px; font-size: 15px; font-weight: 600; background: var(--accent);
  color: #fff; border: 0; border-radius: var(--radius); cursor: pointer;
  box-shadow: var(--shadow); transition: background .15s;
}
#go:hover { background: var(--accent-d); }
#go:active { transform: translateY(1px); }

/* ── tabs ─────────────────────────────────────────────────────────────── */
.tabs {
  display: flex; gap: 8px; padding: 10px 20px; max-width: 1180px; margin: 0 auto;
  width: 100%; flex-wrap: wrap; overflow-x: auto; -webkit-overflow-scrolling: touch;
}
.tab {
  padding: 8px 15px; background: var(--panel); border: 1.5px solid var(--border);
  border-radius: 999px; cursor: pointer; font-size: 13.5px; color: var(--dim);
  white-space: nowrap; transition: all .12s;
}
.tab:hover { border-color: var(--accent); color: var(--accent-d); }
.tab.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.tab .n { opacity: .8; margin-left: 6px; font-size: 11px; }

/* ── layout ───────────────────────────────────────────────────────────── */
main {
  display: grid; grid-template-columns: 260px 1fr; gap: 22px;
  max-width: 1180px; margin: 10px auto 48px; padding: 0 20px; width: 100%;
}
.facets { display: flex; flex-direction: column; gap: 14px; }
.facet { background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px; box-shadow: var(--shadow); }
.facet h3 { margin: 0 0 10px; font-size: 11.5px; text-transform: uppercase; letter-spacing: .6px; color: var(--muted); font-weight: 700; }
.facet .row { display: flex; justify-content: space-between; gap: 8px; cursor: pointer; padding: 5px 6px; margin: 0 -6px; border-radius: 7px; font-size: 13.5px; }
.facet .row:hover { background: var(--accent-soft); color: var(--accent-d); }
.facet .row.active { background: var(--accent-soft); color: var(--accent-d); font-weight: 600; }
.facet .row span:first-child { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.facet .row .c { color: var(--muted); font-variant-numeric: tabular-nums; flex-shrink: 0; }
.yearbox { display: flex; gap: 8px; }
.yearbox input { width: 100%; padding: 8px; background: var(--panel); border: 1.5px solid var(--border); border-radius: 8px; color: var(--fg); font-size: 14px; }
.yearbox input:focus { outline: none; border-color: var(--accent); }

/* ── results ──────────────────────────────────────────────────────────── */
.toolbar { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 14px; flex-wrap: wrap; }
.summary { color: var(--dim); font-size: 13.5px; }
.sort { font-size: 13px; color: var(--dim); }
.sort select { background: var(--panel); color: var(--fg); border: 1.5px solid var(--border); border-radius: 8px; padding: 7px 10px; font-size: 13.5px; }
.facets-toggle {
  display: none; padding: 9px 16px; font-size: 14px; font-weight: 600;
  background: var(--panel); color: var(--accent-d); border: 1.5px solid var(--accent);
  border-radius: 10px; cursor: pointer; align-items: center; gap: 6px;
}
.results { display: flex; flex-direction: column; gap: 12px; }
.card {
  background: var(--panel); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 16px 18px; cursor: pointer; box-shadow: var(--shadow);
  transition: box-shadow .15s, transform .05s, border-color .15s;
}
.card:hover { border-color: #f0c9a8; box-shadow: var(--shadow-lg); }
.card:active { transform: translateY(1px); }
.card h2 { margin: 0 0 8px; font-size: 16.5px; line-height: 1.4; font-weight: 650; color: #15161a; }
.meta { font-size: 13px; color: var(--dim); display: flex; gap: 9px; flex-wrap: wrap; align-items: center; }
.meta .authors { color: var(--fg); font-weight: 500; }
.badge { font-size: 11.5px; padding: 3px 9px; border-radius: 999px; background: var(--chip); color: var(--dim); }
.badge.oa { background: var(--oa-soft); color: var(--oa); font-weight: 600; }
.badge.cite { background: var(--accent-soft); color: var(--accent-d); font-weight: 600; }
.snippet { margin: 9px 0 0; font-size: 13.5px; color: var(--dim); display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }

.pager { display: flex; gap: 10px; justify-content: center; align-items: center; margin-top: 24px; }
.pager button { padding: 10px 16px; background: var(--panel); border: 1.5px solid var(--border); border-radius: 10px; color: var(--fg); cursor: pointer; font-size: 14px; box-shadow: var(--shadow); }
.pager button:hover:not(:disabled) { border-color: var(--accent); color: var(--accent-d); }
.pager button:disabled { opacity: .4; cursor: default; }

.empty { text-align: center; color: var(--dim); padding: 64px 20px; }
.spinner { text-align: center; color: var(--muted); padding: 44px; }

/* ── modal ────────────────────────────────────────────────────────────── */
.modal { position: fixed; inset: 0; background: rgba(16,24,40,.45); display: flex; align-items: flex-start; justify-content: center; padding: 40px 16px; overflow-y: auto; z-index: 80; backdrop-filter: blur(2px); }
.modal.hidden { display: none; }
.modal-card { background: var(--panel); border-radius: 16px; max-width: 820px; width: 100%; padding: 28px; position: relative; box-shadow: var(--shadow-lg); }
.modal-close { position: absolute; top: 14px; right: 16px; background: var(--chip); border: 0; color: var(--dim); font-size: 16px; cursor: pointer; width: 32px; height: 32px; border-radius: 50%; }
.modal-close:hover { background: var(--accent-soft); color: var(--accent-d); }
.modal-card h2 { margin: 0 36px 12px 0; font-size: 22px; line-height: 1.32; font-weight: 700; }
.kv { display: grid; grid-template-columns: 150px 1fr; gap: 7px 16px; margin: 16px 0; font-size: 14px; }
.kv .k { color: var(--muted); }
.refs h3 { font-size: 12px; text-transform: uppercase; letter-spacing: .5px; color: var(--muted); margin: 18px 0 8px; }
.refs ul { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 7px; }
.refs li { font-size: 13.5px; padding: 9px 11px; background: var(--panel2); border-radius: 9px; cursor: pointer; }
.refs li:hover { background: var(--accent-soft); color: var(--accent-d); }
.tabs2 { display: flex; gap: 8px; margin-top: 18px; }
.tabs2 button { background: var(--panel2); border: 1.5px solid var(--border); color: var(--dim); border-radius: 9px; padding: 8px 14px; cursor: pointer; font-size: 13.5px; }
.tabs2 button.active { color: #fff; background: var(--accent); border-color: var(--accent); }

footer { text-align: center; color: var(--muted); font-size: 12px; padding: 22px; border-top: 1px solid var(--border); background: var(--panel); }

/* backdrop for the mobile filter drawer */
.backdrop { position: fixed; inset: 0; background: rgba(16,24,40,.4); z-index: 55; display: none; }
.backdrop.show { display: block; }

/* ── mobile ───────────────────────────────────────────────────────────── */
@media (max-width: 820px) {
  header { padding: 12px 16px; }
  .tag { display: none; }
  .searchbar { padding: 14px 16px 4px; gap: 8px; }
  #go { padding: 0 18px; }
  .tabs { padding: 8px 16px; }
  main { grid-template-columns: 1fr; padding: 0 16px; margin-top: 6px; gap: 16px; }
  .facets-toggle { display: inline-flex; }

  /* facets become a slide-in drawer */
  .facets {
    position: fixed; top: 0; left: 0; bottom: 0; width: 84%; max-width: 330px;
    z-index: 60; background: var(--bg); padding: 18px 16px calc(env(safe-area-inset-bottom) + 20px);
    overflow-y: auto; transform: translateX(-102%); transition: transform .26s ease;
    box-shadow: var(--shadow-lg); gap: 12px;
  }
  .facets.open { transform: translateX(0); }
  .facets::before { content: "Filters"; font-weight: 700; font-size: 16px; margin-bottom: 4px; }

  .card { padding: 14px 15px; }
  .card h2 { font-size: 16px; }
  .modal { padding: 0; align-items: stretch; }
  .modal-card { border-radius: 0; min-height: 100%; padding: 22px 18px calc(env(safe-area-inset-bottom) + 22px); }
  .kv { grid-template-columns: 110px 1fr; }
}