/* ---------------------------------------------------------------------------
   Additions on top of the Academic Project Page Template (static/css/index.css)
   - a slim sticky top bar linking back to the homepage
   - an EN / 中文 language switch
   - a placeholder block used until the real video is dropped in
   --------------------------------------------------------------------------- */

/* --- bilingual content ---------------------------------------------------- */
.lang-zh {
  font-family: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC",
    "Noto Sans CJK SC", sans-serif;
}

/* --- top bar -------------------------------------------------------------- */
.page-topbar {
  position: sticky;
  top: 0;
  z-index: 30;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.6rem 1.25rem;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: saturate(180%) blur(10px);
  -webkit-backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--border-color);
}

.page-topbar .topbar-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.page-topbar a.topbar-link,
.page-topbar button.topbar-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--text-secondary);
  background: transparent;
  border: 1px solid transparent;
  border-radius: 999px;
  padding: 0.35rem 0.8rem;
  cursor: pointer;
  transition: var(--transition);
}

.page-topbar a.topbar-link:hover,
.page-topbar button.topbar-link:hover {
  color: var(--primary-color);
  border-color: var(--border-color);
  background: var(--background-secondary);
}

.page-topbar .lang-switch {
  border-color: var(--border-color);
}

/* --- hero ----------------------------------------------------------------- */
.publication-title .title-zh {
  font-size: 0.62em;
  font-weight: 600;
  color: var(--text-secondary);
  display: block;
  margin-top: 0.6rem;
}

.publication-venue-line {
  margin-top: 0.75rem;
}

.project-role {
  display: inline-block;
  margin-top: 0.5rem;
  padding: 0.25rem 0.8rem;
  border-radius: 999px;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary-color);
  background: rgba(37, 99, 235, 0.08);
}

/* --- highlights ----------------------------------------------------------- */
.highlights {
  list-style: none;
  margin: 0;
  padding: 0;
}

.highlights li {
  position: relative;
  padding: 1rem 1.25rem 1rem 1.5rem;
  margin-bottom: 0.75rem;
  border-left: 3px solid var(--primary-color);
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
  background: var(--background-secondary);
  text-align: left;
}

.highlights li strong {
  color: var(--text-primary);
}

/* --- future work ---------------------------------------------------------- */
.future-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem;
  margin: 1.6rem 0 1.4rem;
}

.future-stat {
  padding: 0.9rem 1rem 0.85rem;
  border: 1px solid var(--border-color);
  border-radius: var(--border-radius);
  background: var(--background-secondary);
  text-align: left;
}

.future-stat .fs-label {
  display: block;
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--text-light);
  margin-bottom: 0.5rem;
}

.future-stat .fs-value {
  display: block;
  font-size: 1.7rem;
  font-weight: 800;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--primary-color);
  font-variant-numeric: tabular-nums;
}

.future-stat .fs-value small {
  font-size: 0.95rem;
  font-weight: 700;
  margin-left: 0.1rem;
}

.future-stat .fs-vs {
  display: block;
  margin-top: 0.45rem;
  font-size: 0.76rem;
  line-height: 1.45;
  color: var(--text-secondary);
  font-variant-numeric: tabular-nums;
}

.future-note {
  margin-top: 1.4rem;
  padding: 0.9rem 1.1rem;
  border-left: 3px solid var(--border-color);
  border-radius: 0 var(--border-radius) var(--border-radius) 0;
  background: var(--background-secondary);
  font-size: 0.82rem;
  line-height: 1.7;
  color: var(--text-secondary);
  text-align: left;
}

.future-note strong {
  color: var(--text-primary);
}

@media (max-width: 720px) {
  .future-stats {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* --- video placeholder ---------------------------------------------------- */
.video-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.6rem;
  min-height: 340px;
  padding: 2rem;
  text-align: center;
  color: var(--text-secondary);
  border: 2px dashed var(--border-color);
  border-radius: 0;
  background: var(--background-secondary);
}

.video-placeholder .placeholder-icon {
  width: 56px;
  height: 56px;
  color: var(--text-light);
}

.video-placeholder .placeholder-title {
  font-weight: 700;
  color: var(--text-primary);
  font-size: 1.1rem;
}

.video-placeholder .placeholder-hint {
  font-size: 0.85rem;
  color: var(--text-light);
  max-width: 34rem;
}

/* --- misc ----------------------------------------------------------------- */
.button.is-dark .icon svg {
  width: 1em;
  height: 1em;
  fill: currentColor;
}

.footer .home-link {
  font-weight: 600;
}

@media (max-width: 640px) {
  .page-topbar {
    padding: 0.5rem 0.75rem;
  }
  .page-topbar a.topbar-link,
  .page-topbar button.topbar-link {
    font-size: 0.8rem;
    padding: 0.3rem 0.6rem;
  }
}

/* --- bilingual visibility -------------------------------------------------
   Only the *hidden* language is touched, so the visible one keeps whatever
   display value it was given above (inline, inline-block, block, ...).
   Keep these two rules at the very end of the file.
   --------------------------------------------------------------------------- */
html:not(.lang-mode-zh) .lang-zh {
  display: none !important;
}
html.lang-mode-zh .lang-en {
  display: none !important;
}