/* =========================================================
   Look Closer: Action-Guided Dense Visual Dynamics
   for Proficiency Estimation — Project Page
   ========================================================= */

:root {
  --bg:           #ffffff;
  --bg-alt:       #f5f6fb;
  --text:         #1c1f2b;
  --text-soft:    #565b70;
  --text-muted:   #8b90a4;
  --accent:       #4a5bd4;
  --accent-dark:  #3344b8;
  --ink:          #1c1f2b;
  --border:       #e4e6ef;
  --radius:       14px;
  --maxw:         1060px;
  --maxw-narrow:  780px;
  --shadow:       0 10px 30px rgba(28, 31, 43, 0.08);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI',
               Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img { max-width: 100%; display: block; }

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

.container {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}
.container.narrow { max-width: var(--maxw-narrow); }

/* ========================== HEADER ========================== */
.site-header {
  text-align: center;
  padding: 66px 0 48px;
  background: linear-gradient(180deg, #eef0fa 0%, #ffffff 100%);
  border-bottom: 1px solid var(--border);
}

.venue {
  font-size: 0.82rem;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--accent);
  margin: 0 0 18px;
}

.paper-title {
  font-size: 2.55rem;
  line-height: 1.18;
  font-weight: 800;
  letter-spacing: -0.022em;
  margin: 0 auto 26px;
  max-width: 900px;
}

.authors {
  font-size: 1.05rem;
  margin: 0 auto 10px;
  max-width: 1020px;          /* wide enough to keep all authors on one line */
}
.author {
  color: var(--ink);
  font-weight: 600;
  white-space: nowrap;        /* never split a single name across two lines */
}
/* Linked authors (a.author) carry a visible underline so it is clear
   they are clickable; the plain-text authors (span.author) do not. */
a.author {
  border-bottom: 1.5px solid var(--accent);
  transition: color 0.15s ease, border-color 0.15s ease;
}
a.author:hover {
  color: var(--accent);
  border-color: var(--accent-dark);
  text-decoration: none;
}
.authors sup,
.affiliations sup {
  color: var(--accent);
  font-weight: 700;
  font-size: 0.72em;
}

.affiliations {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 4px 22px;
  font-size: 0.97rem;
  color: var(--text-soft);
  margin: 0 0 30px;
}

/* ====================== ACTION BUTTONS ====================== */
.action-buttons {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 24px;
  background: var(--ink);
  color: #ffffff;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  transition: background 0.16s ease, transform 0.16s ease,
              box-shadow 0.16s ease;
}
.btn:hover {
  background: var(--accent);
  text-decoration: none;
  transform: translateY(-2px);
  box-shadow: 0 6px 18px rgba(74, 91, 212, 0.32);
}
.btn-icon { font-size: 1rem; line-height: 1; }

/* ========================= SECTIONS ========================= */
main { display: block; }

.section { padding: 52px 0; }
.section:nth-of-type(even) { background: var(--bg-alt); }

.section-title {
  font-size: 1.62rem;
  font-weight: 700;
  text-align: center;
  letter-spacing: -0.015em;
  margin: 0 0 30px;
}
.section-title::after {
  content: "";
  display: block;
  width: 54px;
  height: 3px;
  margin: 12px auto 0;
  border-radius: 3px;
  background: var(--accent);
}

/* ===================== FIGURE CAROUSEL ====================== */
.carousel { position: relative; }

/* Fixed-ratio box: the figure area keeps the SAME size no matter
   which image is shown, so the abstract below never jumps. */
.carousel-viewport {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}

/* Slides are stacked and cross-fade slowly between figures. */
.carousel-slide {
  position: absolute;
  inset: 0;
  margin: 0;
  opacity: 0;
  transition: opacity 1.2s ease-in-out;
}
.carousel-slide.is-active {
  opacity: 1;
}
.carousel-slide img {
  width: 100%;
  height: 100%;
  object-fit: contain;   /* fit any figure size without cropping or stretching */
  padding: 18px;
}

/* Arrows */
.carousel-arrow {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--border);
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.92);
  color: var(--ink);
  font-size: 1.5rem;
  line-height: 1;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(28, 31, 43, 0.12);
  transition: background 0.16s ease, color 0.16s ease, transform 0.16s ease;
  z-index: 2;
}
.carousel-arrow:hover {
  background: var(--accent);
  color: #ffffff;
  transform: translateY(-50%) scale(1.07);
}
.carousel-arrow.prev { left: 14px; }
.carousel-arrow.next { right: 14px; }

/* Dots */
.carousel-controls {
  display: flex;
  justify-content: center;
  margin-top: 18px;
}
.carousel-dots {
  display: flex;
  gap: 10px;
}
.carousel-dot {
  width: 10px;
  height: 10px;
  padding: 0;
  border: none;
  border-radius: 50%;
  background: #cfd2e2;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.2s ease;
}
.carousel-dot:hover { background: #a9adc6; }
.carousel-dot.is-active {
  background: var(--accent);
  transform: scale(1.3);
}

/* Caption */
.carousel-caption {
  max-width: 860px;
  min-height: 4.6rem;      /* reserve space so captions of different
                              lengths do not shift the abstract below */
  margin: 16px auto 0;
  text-align: center;
  font-size: 0.93rem;
  color: var(--text-soft);
}

/* ========================= ABSTRACT ========================= */
.abstract {
  margin: 0;
  font-size: 1.06rem;
  text-align: justify;
  hyphens: auto;
  color: var(--text);
}

/* ===================== PRESENTATION VIDEO =================== */
.video-card {
  margin: 0;
  background: #000000;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.video-card video {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  background: #000000;
}
.video-card figcaption {
  background: var(--bg);
  color: var(--text-soft);
  font-size: 0.9rem;
  font-weight: 600;
  text-align: center;
  padding: 10px 12px;
}

/* ======================== DEMO GRID ========================= */
.video-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);   /* 2 columns x 3 rows */
  gap: 22px;
}

/* ========================== FOOTER ========================== */
.site-footer {
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
  text-align: center;
  padding: 34px 0;
}
.site-footer p {
  margin: 4px 0;
  font-size: 0.92rem;
  color: var(--text-soft);
}
.site-footer .muted {
  color: var(--text-muted);
  font-size: 0.84rem;
}

/* ======================== RESPONSIVE ======================== */
@media (max-width: 640px) {
  .site-header { padding: 48px 0 38px; }
  .paper-title { font-size: 1.85rem; }
  .authors { font-size: 1rem; }
  .section { padding: 40px 0; }
  .section-title { font-size: 1.4rem; }
  .video-grid { grid-template-columns: 1fr; }
  .carousel-arrow { width: 38px; height: 38px; font-size: 1.25rem; }
  .abstract { font-size: 1rem; }
}