:root {
  --bg: #ffffff;
  --fg: #1f2328;
  --muted: #57606a;
  --accent: #6d4fc2;
  --accent-2: #2f6fed;
  --border: #e6e8eb;
  --card: #f6f8fa;
  --max: 1020px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  color: var(--fg);
  background: var(--bg);
  line-height: 1.65;
  font-size: 17px;
}
a { color: var(--accent-2); }
.container { max-width: var(--max); margin: 0 auto; padding: 0 20px; }

/* ---------- hero ---------- */
header.hero { text-align: center; padding: 56px 0 20px; }
h1.title {
  font-family: "Source Serif 4", "Source Serif Pro", Charter, Georgia, "Times New Roman", serif;
  font-size: 3.6rem; line-height: 1.15; margin: 0 0 22px; font-weight: 800; letter-spacing: -0.01em;
}
h1.title .brand {
  font-style: normal;
  background: linear-gradient(90deg, #3b8fe0 0%, #3fb8c9 25%, #63bf5a 55%, #b9c23a 80%, #e6b83a 100%);
  -webkit-background-clip: text; background-clip: text;
  color: transparent; -webkit-text-fill-color: transparent;
}
h1.title .sub {
  display: block; font-size: 2.05rem; line-height: 1.25; font-weight: 700; font-style: normal;
  color: var(--fg); margin-top: 10px;
}
h1.title .sub .hl {
  background: linear-gradient(90deg, #f0a020 0%, #ef7f8a 45%, #b48cf2 100%);
  -webkit-background-clip: text; background-clip: text;
  color: transparent; -webkit-text-fill-color: transparent;
}
.authors { font-size: 1.1rem; margin-bottom: 6px; }
.authors a { text-decoration: none; }
.authors a:hover { text-decoration: underline; }
.authors sup, .affils sup { font-size: 0.7em; }
.affils { color: var(--muted); }
.notes { color: var(--muted); font-size: 0.92rem; }
.buttons { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin: 26px 0 10px; }
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 9px 17px; border-radius: 999px;
  background: #24292f; color: #fff; text-decoration: none;
  font-weight: 600; font-size: 0.95rem;
  transition: transform .12s ease, background .12s ease;
}
.btn:hover { background: var(--accent); transform: translateY(-1px); }
.btn.disabled, .btn.disabled:hover { background: var(--border); color: var(--muted); cursor: default; transform: none; }
.btn svg { width: 18px; height: 18px; fill: currentColor; flex: none; }

/* ---------- content ---------- */
section { padding: 34px 0 10px; }
section h2 { font-size: 1.65rem; margin: 0 0 16px; letter-spacing: -0.01em; }
section h3 { font-size: 1.15rem; margin: 26px 0 10px; }
section p { margin: 0 0 12px; }
figure { margin: 0; }
figure img { width: 100%; height: auto; border-radius: 8px; display: block; }
figcaption { color: var(--muted); font-size: 0.93rem; margin-top: 10px; text-align: center; }
.card { background: var(--card); border: 1px solid var(--border); border-radius: 12px; padding: 22px 24px; }
.abstract p { text-align: justify; }
.highlights { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 14px; margin-top: 18px; }
.highlight { background: #fff; border: 1px solid var(--border); border-radius: 10px; padding: 14px 16px; font-size: 0.95rem; }
.highlight b { display: block; color: var(--accent); margin-bottom: 4px; font-size: 1rem; }
.formula { text-align: center; font-size: 1.1rem; margin: 14px 0; font-family: "Cambria Math", "Times New Roman", serif; }
.grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; align-items: start; }

/* ---------- tables ---------- */
.table-wrap { overflow-x: auto; border: 1px solid var(--border); border-radius: 10px; }
table { border-collapse: collapse; width: 100%; font-size: 0.88rem; }
th, td { padding: 6px 9px; text-align: center; border-bottom: 1px solid var(--border); white-space: nowrap; }
tr:last-child td { border-bottom: none; }
th { background: var(--card); font-weight: 600; position: sticky; top: 0; }
td:first-child, th:first-child { text-align: left; }
td.best { color: #d83931; font-weight: 700; }
td.second { color: #2f6fed; font-weight: 600; }
tr.ours { background: #f7f4fd; }
tr.ours td:first-child { font-weight: 700; }
tr.sep td { border-top: 2px solid var(--border); }
.grid-2 th, .grid-2 td { padding: 5px 6px; font-size: 0.84rem; }
.legend { color: var(--muted); font-size: 0.9rem; margin: 10px 0 0; }
.tabs { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
.tab {
  padding: 6px 14px; border-radius: 8px; border: 1px solid var(--border);
  background: #fff; cursor: pointer; font-weight: 600; font-size: 0.92rem; color: var(--fg);
}
.tab.active { background: var(--accent); color: #fff; border-color: var(--accent); }
.panel { display: none; }
.panel.active { display: block; }

/* ---------- gallery ---------- */
.gallery details { border: 1px solid var(--border); border-radius: 10px; margin-top: 12px; overflow: hidden; }
.gallery summary { cursor: pointer; font-weight: 600; padding: 12px 16px; background: var(--card); list-style: none; }
.gallery summary::-webkit-details-marker { display: none; }
.gallery summary::before { content: "▸ "; color: var(--accent); }
.gallery details[open] summary::before { content: "▾ "; }
.gallery details figure { padding: 14px; }

/* ---------- video ---------- */
.video-card { display: flex; flex-wrap: wrap; gap: 20px; align-items: center; justify-content: space-between; }
.video-card p { margin: 0; max-width: 640px; }

/* ---------- bibtex ---------- */
pre.bibtex {
  background: var(--card); border: 1px solid var(--border); border-radius: 12px;
  padding: 18px 20px; overflow-x: auto; font-size: 0.85rem; line-height: 1.5; position: relative; margin: 0;
}
.bib-wrap { position: relative; }
.copy-btn {
  position: absolute; top: 10px; right: 10px;
  border: 1px solid var(--border); background: #fff; color: var(--fg);
  border-radius: 6px; padding: 4px 10px; font-size: 0.8rem; cursor: pointer;
}
.copy-btn:hover { background: var(--accent); color: #fff; border-color: var(--accent); }

footer {
  text-align: center; color: var(--muted); font-size: 0.9rem;
  padding: 36px 0 30px; border-top: 1px solid var(--border); margin-top: 44px;
}

@media (max-width: 760px) {
  body { font-size: 16px; }
  h1.title { font-size: 2.3rem; }
  h1.title .sub { font-size: 1.35rem; }
  .grid-2 { grid-template-columns: 1fr; }
  header.hero { padding-top: 36px; }
}