/* ── Reset & variables ─────────────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --blue:       #1a6fa8;
  --blue-light: #e8f2fb;
  --blue-dark:  #0d4d7a;
  --red:        #c0392b;
  --green:      #27ae60;
  --bg:         #ffffff;
  --surface:    #f8f9fc;
  --border:     #e0e6ef;
  --text:       #1a1a2e;
  --muted:      #5a6a82;
  --radius:     12px;
  --shadow:     0 4px 24px rgba(26,111,168,0.10);
  --transition: 0.3s ease;
  --max-w:      900px;
}

html { scroll-behavior: smooth; }
body { font-family: 'Inter', system-ui, sans-serif; color: var(--text);
       background: var(--bg); line-height: 1.7; font-size: 16px; }

/* ── Utilities ─────────────────────────────────────────────────────────────── */
.container { max-width: var(--max-w); margin: 0 auto; padding: 0 24px; }
.tag { display: inline-block; background: var(--blue-light); color: var(--blue-dark);
       border-radius: 6px; font-size: 0.72rem; font-weight: 600;
       padding: 3px 9px; letter-spacing: 0.04em; text-transform: uppercase; }
.badge { display: inline-flex; align-items: center; gap: 6px;
         background: var(--surface); border: 1px solid var(--border);
         border-radius: 20px; padding: 6px 14px; font-size: 0.85rem;
         font-weight: 500; text-decoration: none; color: var(--text);
         transition: var(--transition); }
.badge:hover { border-color: var(--blue); color: var(--blue); transform: translateY(-1px); }
.badge img { height: 16px; }
section { padding: 80px 0; }
section:nth-child(even) { background: var(--surface); }
h2 { font-size: 1.85rem; font-weight: 700; margin-bottom: 12px;
     color: var(--text); letter-spacing: -0.02em; }
h3 { font-size: 1.15rem; font-weight: 600; margin-bottom: 8px; color: var(--blue-dark); }
p  { color: var(--muted); }
.section-label { display: block; font-size: 0.72rem; font-weight: 700;
                 letter-spacing: 0.12em; text-transform: uppercase;
                 color: var(--blue); margin-bottom: 10px; }

/* ── Nav ───────────────────────────────────────────────────────────────────── */
nav { position: sticky; top: 0; z-index: 100; background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px); border-bottom: 1px solid var(--border);
      padding: 0 24px; }
nav .inner { max-width: var(--max-w); margin: 0 auto;
             display: flex; align-items: center; gap: 32px; height: 52px; }
nav a { font-size: 0.85rem; font-weight: 500; color: var(--muted);
        text-decoration: none; transition: color var(--transition); }
nav a:hover, nav a.active { color: var(--blue); }
nav .logo { font-weight: 700; color: var(--text); margin-right: auto; font-size: 0.95rem; }

/* ── Hero ──────────────────────────────────────────────────────────────────── */
#hero { padding: 72px 0 64px; text-align: center; background: var(--bg); }
#hero h1 { font-size: clamp(2rem, 5vw, 2.8rem); font-weight: 800;
           letter-spacing: -0.04em; line-height: 1.2; margin-bottom: 14px; }
#hero h1 span { color: var(--blue); }
#hero .subtitle { font-size: 1.1rem; color: var(--muted); max-width: 620px;
                  margin: 0 auto 28px; }
.authors { font-size: 0.93rem; color: var(--muted); margin-bottom: 6px; }
.affil   { font-size: 0.83rem; color: var(--muted); margin-bottom: 28px; }
.badges  { display: flex; gap: 10px; justify-content: center; flex-wrap: wrap; }
.venue   { display: inline-block; background: var(--blue); color: #fff;
           border-radius: 6px; font-size: 0.78rem; font-weight: 700;
           padding: 3px 10px; margin-bottom: 20px; letter-spacing: 0.03em; }

/* ── Abstract ──────────────────────────────────────────────────────────────── */
#abstract .card { background: var(--bg); border: 1px solid var(--border);
                  border-radius: var(--radius); padding: 32px 36px;
                  box-shadow: var(--shadow); }
#abstract p { color: var(--text); font-size: 0.98rem; line-height: 1.8; }

/* ── Overview figure ───────────────────────────────────────────────────────── */
#overview figure { margin-top: 36px; text-align: center; }
#overview figure img { max-width: 100%; border-radius: var(--radius);
                       border: 1px solid var(--border); box-shadow: var(--shadow); }
#overview figcaption { margin-top: 12px; font-size: 0.85rem; color: var(--muted); }

/* ── Method ────────────────────────────────────────────────────────────────── */
.method-body { display: grid; grid-template-columns: 1fr 1fr;
               gap: 32px; margin-top: 28px; align-items: start; }
@media (max-width: 680px) { .method-body { grid-template-columns: 1fr; } }
.method-prose p { font-size: 0.95rem; line-height: 1.8; color: var(--text); }

.method-concepts { display: flex; flex-direction: column; gap: 14px; }
.concept-card { display: flex; gap: 14px; align-items: flex-start;
                background: var(--bg); border: 1px solid var(--border);
                border-radius: var(--radius); padding: 18px 20px;
                box-shadow: var(--shadow);
                transition: transform var(--transition), box-shadow var(--transition); }
.concept-card:hover { transform: translateY(-2px);
                      box-shadow: 0 8px 28px rgba(26,111,168,0.13); }
.concept-icon { font-size: 1.5rem; line-height: 1; flex-shrink: 0; margin-top: 2px; }
.concept-card h3 { font-size: 0.95rem; margin-bottom: 4px; }
.concept-card p  { font-size: 0.85rem; }


/* ── Feature Shift ─────────────────────────────────────────────────────────── */
#shift .player { background: var(--bg); border: 1px solid var(--border);
                 border-radius: var(--radius); box-shadow: var(--shadow);
                 overflow: hidden; margin-top: 32px; }
.player-header { background: var(--blue); color: #fff;
                 padding: 14px 24px; display: flex; align-items: center; gap: 12px; }
.player-header h3 { color: #fff; margin: 0; font-size: 1rem; }
.player-body { padding: 24px; }
.iter-label { font-size: 0.9rem; font-weight: 600; color: var(--blue);
              margin-bottom: 16px; display: flex; align-items: center; gap: 8px; }
.iter-label .pill { background: var(--blue); color: #fff; border-radius: 20px;
                    padding: 2px 12px; font-size: 0.78rem; }

#tsne-plot { width: 100%; height: 400px; }

.viz-images { display: grid; grid-template-columns: repeat(3, 1fr);
              gap: 12px; margin-top: 16px; }
.viz-img-item img { width: 100%; border-radius: 8px;
                    border: 1px solid var(--border); display: block; }
.viz-img-item .img-label { font-size: 0.72rem; font-weight: 600; color: var(--muted);
                           text-transform: uppercase; letter-spacing: 0.06em;
                           margin-bottom: 5px; }

.controls { display: flex; align-items: center; gap: 16px; margin-top: 20px; flex-wrap: wrap; }
.btn-play  { background: var(--blue); color: #fff; border: none;
             border-radius: 8px; padding: 9px 22px; font-weight: 600;
             font-size: 0.9rem; cursor: pointer; transition: var(--transition);
             display: flex; align-items: center; gap: 8px; }
.btn-play:hover { background: var(--blue-dark); }
.slider-wrap { flex: 1; display: flex; flex-direction: column; gap: 4px; }
.slider-wrap label { font-size: 0.78rem; color: var(--muted); font-weight: 500; }
input[type=range] { width: 100%; accent-color: var(--blue); cursor: pointer; }

.score-bar { margin-top: 20px; }
.score-bar-label { font-size: 0.82rem; color: var(--muted); margin-bottom: 6px; font-weight: 500; }
.score-track { height: 8px; background: var(--border); border-radius: 4px; overflow: hidden; }
.score-fill  { height: 100%; background: linear-gradient(90deg, var(--blue-light), var(--blue));
               border-radius: 4px; transition: width 0.4s ease; }

/* iteration dots */
.iter-dots { display: flex; gap: 6px; flex-wrap: wrap; margin-top: 16px; }
.iter-dot  { width: 28px; height: 28px; border-radius: 6px; cursor: pointer;
             background: var(--border); display: flex; align-items: center;
             justify-content: center; font-size: 0.72rem; font-weight: 600;
             color: var(--muted); transition: var(--transition); }
.iter-dot.active { background: var(--blue); color: #fff; }
.iter-dot:hover:not(.active) { background: var(--blue-light); color: var(--blue); }

/* ── Results ───────────────────────────────────────────────────────────────── */
.result-cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px,1fr));
                gap: 16px; margin-top: 32px; }
.result-card  { background: var(--bg); border: 1px solid var(--border);
                border-radius: var(--radius); padding: 24px; text-align: center;
                box-shadow: var(--shadow); }
.result-card .number { font-size: 2.2rem; font-weight: 800; color: var(--blue);
                       letter-spacing: -0.03em; line-height: 1; }
.result-card .number.green { color: var(--green); }
.result-card .desc { font-size: 0.83rem; color: var(--muted); margin-top: 6px; }
.result-card .model { font-size: 0.75rem; font-weight: 600; color: var(--blue);
                      text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 4px; }

.results-table { margin-top: 36px; overflow-x: auto; }
table { width: 100%; border-collapse: collapse; font-size: 0.87rem; }
thead th { background: var(--blue); color: #fff; padding: 10px 14px;
           text-align: center; font-weight: 600; }
thead th:first-child { text-align: left; border-radius: 8px 0 0 0; }
thead th:last-child  { border-radius: 0 8px 0 0; }
tbody td { padding: 10px 14px; border-bottom: 1px solid var(--border);
           text-align: center; color: var(--text); }
tbody td:first-child { text-align: left; font-weight: 600; }
tbody tr:last-child td { border-bottom: none; }
tbody tr:hover td { background: var(--blue-light); }
.gain { color: var(--green); font-weight: 700; }

/* ── Demo comparison ───────────────────────────────────────────────────────── */
.comparison-grid { display: grid; grid-template-columns: repeat(3,1fr);
                   gap: 14px; margin-top: 32px; }
.cmp-item { display: flex; flex-direction: column; gap: 8px; }
.cmp-item img { width: 100%; border-radius: 8px; border: 1px solid var(--border); }
.cmp-item span { font-size: 0.78rem; font-weight: 600; color: var(--muted);
                 text-align: center; text-transform: uppercase; letter-spacing: 0.06em; }

/* ── BibTeX ────────────────────────────────────────────────────────────────── */
#citation pre { background: #1a1a2e; color: #a8d8f0; border-radius: var(--radius);
                padding: 24px; font-size: 0.83rem; overflow-x: auto;
                line-height: 1.6; margin-top: 20px; }
.copy-btn { background: var(--blue); color: #fff; border: none; border-radius: 8px;
            padding: 8px 18px; cursor: pointer; font-size: 0.85rem; font-weight: 600;
            transition: var(--transition); margin-top: 12px; }
.copy-btn:hover { background: var(--blue-dark); }
.copy-btn.copied { background: var(--green); }

/* ── Substitution animation ────────────────────────────────────────────────── */
.sub-demo { margin-top: 32px; display: flex; flex-direction: column; gap: 20px; }

/* support card grid */
.sub-grid { display: flex; align-items: flex-start; gap: 12px;
            background: var(--surface); border: 1px solid var(--border);
            border-radius: var(--radius); padding: 16px 20px; }
.sub-class-col { display: flex; flex-direction: column; gap: 8px; flex: 1; }
.sub-class-label { font-size: 0.72rem; font-weight: 700; letter-spacing: 0.1em;
                   text-transform: uppercase; }
.sub-class-label.a { color: #c0392b; }
.sub-class-label.b { color: #1a6fa8; }
.sub-cards { display: flex; flex-wrap: wrap; gap: 8px; }
.sub-divider { width: 1px; background: var(--border); align-self: stretch; margin: 0 4px; }

/* individual support card */
.s-card { position: relative; width: 56px; height: 56px; border-radius: 8px;
          overflow: hidden; cursor: default; flex-shrink: 0;
          transition: transform 0.25s, box-shadow 0.25s, opacity 0.3s;
          border: 2px solid transparent; }
.s-card img { width: 100%; height: 100%; object-fit: cover; display: block; }
.s-card-lbl { position: absolute; bottom: 0; left: 0; right: 0;
              background: rgba(0,0,0,0.55); color: #fff;
              font-size: 0.6rem; font-weight: 700; text-align: center;
              padding: 1px 0; letter-spacing: 0.04em; }
.s-card.cls-a { border-color: #f5b7b1; }
.s-card.cls-b { border-color: #aed6f1; }
.s-card.is-pq { transform: scale(1.18);
                box-shadow: 0 0 0 3px #fff, 0 0 0 6px currentColor;
                animation: pq-pulse 0.7s ease-in-out infinite alternate; z-index: 2; }
.s-card.is-ctx { opacity: 0.35; }
@keyframes pq-pulse { to { box-shadow: 0 0 0 3px #fff, 0 0 0 9px currentColor; } }

/* diagram */
.sub-diagram { position: relative; min-height: 320px;
               background: var(--bg); border: 1px solid var(--border);
               border-radius: var(--radius); overflow: hidden; }
.sub-svg { position: absolute; inset: 0; width: 100%; height: 100%;
           pointer-events: none; overflow: visible; }

/* diagram nodes */
.dn { position: absolute; border-radius: 10px; display: flex;
      flex-direction: column; align-items: center; justify-content: center;
      gap: 4px; font-size: 0.8rem; font-weight: 600; text-align: center;
      transition: box-shadow 0.3s; }

.pq-dn  { left: 5%; top: 12%; width: 13%; padding: 10px 6px;
          background: #fef9e7; border: 2px solid #f39c12; color: #7d6608; }
.ctx-dn { right: 5%; top: 12%; width: 28%; padding: 10px 8px;
          background: var(--surface); border: 1px solid var(--border); }
.enc-dn { left: 50%; transform: translateX(-50%); top: 10%; width: 28%;
          padding: 14px 10px; background: var(--blue-light);
          border: 2px solid var(--blue); color: var(--blue-dark); }
.dec-dn { left: 50%; transform: translateX(-50%); top: 45%; width: 24%;
          padding: 12px 10px; background: #e8f8f5;
          border: 2px solid #1abc9c; color: #0e6655; }
.loss-dn{ left: 50%; transform: translateX(-50%); top: 75%; width: 20%;
          padding: 10px; background: #fdf2f8;
          border: 2px dashed #8e44ad; color: #6c3483; }

.dn-card { width: 56px; height: 56px; border-radius: 8px;
           background: var(--border) center/cover; transition: background 0.3s;
           border: 2px solid #f39c12; }
.dn-label { font-size: 0.68rem; font-weight: 600; color: var(--muted);
            text-transform: uppercase; letter-spacing: 0.05em; }
.ctx-mini-row { display: flex; flex-wrap: wrap; gap: 3px;
                justify-content: center; max-width: 140px; }
.ctx-mini-card { width: 18px; height: 18px; border-radius: 3px;
                 object-fit: cover; display: block; }

.enc-inner { display: flex; flex-direction: column; align-items: center; gap: 6px; }
.enc-title  { font-size: 0.88rem; font-weight: 700; }
.lora-chip  { background: #e74c3c; color: #fff; border-radius: 20px;
              padding: 2px 10px; font-size: 0.72rem; font-weight: 700;
              transition: transform 0.2s, box-shadow 0.2s; }
.lora-chip.pulse { animation: lora-burst 0.5s ease-out; }
@keyframes lora-burst {
  0%   { transform: scale(1);    box-shadow: 0 0 0 0 rgba(231,76,60,0.7); }
  50%  { transform: scale(1.3);  box-shadow: 0 0 0 8px rgba(231,76,60,0); }
  100% { transform: scale(1);    box-shadow: 0 0 0 0 rgba(231,76,60,0); }
}
.enc-dn.active { box-shadow: 0 0 0 3px var(--blue), 0 0 16px rgba(26,111,168,0.3); }
.dec-dn.active { box-shadow: 0 0 0 3px #1abc9c, 0 0 12px rgba(26,188,156,0.3); }
.loss-dn.active{ box-shadow: 0 0 0 3px #8e44ad, 0 0 12px rgba(142,68,173,0.3); }

/* SVG arrow lines */
.sub-svg path.fwd { fill: none; stroke: var(--blue); stroke-width: 2;
                    stroke-linecap: round; marker-end: url(#arr-fwd); }
.sub-svg path.bwd { fill: none; stroke: #e74c3c; stroke-width: 2.5;
                    stroke-dasharray: 6 4; stroke-linecap: round;
                    marker-start: url(#arr-bwd); }
@keyframes dash-travel {
  to { stroke-dashoffset: -100; }
}
.sub-svg path.animating {
  animation: dash-travel 0.6s linear infinite;
}
.sub-svg path.bwd.animating {
  stroke-dasharray: 6 4;
  stroke-dashoffset: 0;
  animation: dash-travel-bwd 0.6s linear infinite;
}
@keyframes dash-travel-bwd {
  to { stroke-dashoffset: 100; }
}

/* phase pills */
.sub-phases { display: flex; gap: 8px; flex-wrap: wrap; }
.sub-phase  { display: flex; align-items: center; gap: 6px; padding: 6px 12px;
              border-radius: 20px; background: var(--surface);
              border: 1px solid var(--border); font-size: 0.8rem;
              color: var(--muted); transition: all 0.3s; }
.ph-dot     { width: 8px; height: 8px; border-radius: 50%; background: var(--border);
              transition: background 0.3s; flex-shrink: 0; }
.sub-phase.active { background: var(--blue-light); border-color: var(--blue);
                    color: var(--blue-dark); }
.sub-phase.active .ph-dot { background: var(--blue); }
.sub-phase.done   { background: #eafaf1; border-color: #27ae60; color: #1e8449; }
.sub-phase.done   .ph-dot { background: #27ae60; }

/* counter */
.sub-counter { font-size: 0.82rem; color: var(--muted); text-align: center;
               padding: 8px; background: var(--surface);
               border-radius: 8px; border: 1px solid var(--border); }
.sub-counter span { font-weight: 700; color: var(--blue); }

/* ── Footer ────────────────────────────────────────────────────────────────── */
footer { padding: 32px 24px; text-align: center; border-top: 1px solid var(--border);
         font-size: 0.83rem; color: var(--muted); }
footer a { color: var(--blue); text-decoration: none; }

/* ── Mobile (≤ 600 px) ─────────────────────────────────────────────────────── */
@media (max-width: 600px) {

  /* Nav: horizontally scrollable so links are never clipped */
  nav { padding: 0 12px; }
  nav .inner {
    gap: 20px;
    overflow-x: auto;
    scrollbar-width: none;
    -webkit-overflow-scrolling: touch;
  }
  nav .inner::-webkit-scrollbar { display: none; }
  nav a, nav .logo { white-space: nowrap; flex-shrink: 0; }

  /* Substitution diagram: give it more vertical room */
  .sub-diagram { min-height: 360px; }

  /* Scale down fixed-size thumbnail cards */
  .dn-card        { width: 40px; height: 40px; }
  .s-card         { width: 44px; height: 44px; }
  .ctx-mini-card  { width: 22px; height: 22px; }
  .ctx-mini-row   { max-width: 100%; flex-direction: column; align-items: center; }

  /* Widen nodes so their content no longer overflows */
  .pq-dn  { width: 18%; left: 2%; }
  .ctx-dn { width: 26%; right: 2%; }
  .enc-dn { width: 32%; }
  .dec-dn { width: 28%; }
  .loss-dn{ width: 24%; }

  /* Keep the three viz images aligned even when labels wrap */
  .viz-img-item .img-label { min-height: 2.4em; }

  /* Shrink diagram text to fit narrower nodes */
  .dn        { font-size: 0.68rem; }
  .dn-label  { font-size: 0.58rem; }
  .enc-title { font-size: 0.78rem; }
  .lora-chip { font-size: 0.6rem; padding: 2px 7px; }
}

/* ── Animations ────────────────────────────────────────────────────────────── */
@keyframes fadeUp { from { opacity:0; transform:translateY(20px); }
                    to   { opacity:1; transform:translateY(0); } }
.fade-up { animation: fadeUp 0.6s ease both; }
.fade-up-1 { animation-delay: 0.1s; }
.fade-up-2 { animation-delay: 0.2s; }
.fade-up-3 { animation-delay: 0.3s; }

/* loading spinner */
.spinner { width: 36px; height: 36px; border: 3px solid var(--border);
           border-top-color: var(--blue); border-radius: 50%;
           animation: spin 0.8s linear infinite; margin: 40px auto; }
@keyframes spin { to { transform: rotate(360deg); } }
.load-msg { text-align: center; color: var(--muted); font-size: 0.9rem; }