:root {
  --accent: #5a4bc2;
  --accent-dark: #43359c;
  --accent-soft: #efedff;
  --orange: #ff8b3d;
  --orange-soft: #fff1e7;
  --green: #208765;
  --green-soft: #eaf7f2;
  --ink: #242424;
  --muted: #666a70;
  --line: #dddddd;
  --panel: #fafafa;
  --paper: #ffffff;
}

html { scroll-behavior: smooth; }

body {
  font-family: "Titillium Web", "HelveticaNeue-Light", "Helvetica Neue Light", "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif;
  font-weight: 300;
  font-size: 17px;
  color: var(--ink);
  background: #ffffff;
  margin: 0 auto;
  line-height: 1.38;
}

@media screen and (min-width: 980px) { body { width: 980px; } }

.container { margin-left: auto; margin-right: auto; padding-left: 16px; padding-right: 16px; }
.paper-title { padding: 30px 0 8px; text-align: center; }

h1 { font-size: 42px; font-weight: 500; line-height: 1.12em; margin: 0 0 12px; text-align: center; }
h2 { font-size: 1.72em; font-weight: 400; margin: 16px 0 8px; text-align: left; }
h3 { font-size: 1.08em; font-weight: 600; margin: 12px 0 8px; text-align: left; }
p { line-height: 1.38em; margin: 0.42em 0; }

section { margin: 34px 0; text-align: left; clear: both; }
hr { height: 1px; border: 0; border-top: 1px solid var(--line); margin: 0 0 14px; }

a:link, a:visited { color: var(--accent); text-decoration: none; }
a:hover, a:focus { color: #208799; text-decoration: underline; }

figure { display: block; margin: 12px auto 18px; text-align: center; }
img { max-width: 100%; height: auto; }
figcaption, .caption-text { font-size: 15.5px; color: var(--muted); margin-top: 7px; margin-bottom: 8px; line-height: 1.35em; text-align: center; }
.wide-img { width: 100%; border: 1px solid #eeeeee; border-radius: 6px; background: #ffffff; box-shadow: 0 1px 0 rgba(0,0,0,0.03); }

.author-row-new { text-align: center; margin-top: 6px; }
.author-row-new a, .author-row-new span { display: inline-block; font-size: 20px; padding: 3px; color: var(--accent); }
.author-row-new sup { color: #313436; font-size: 12px; }
.affiliations { font-size: 18px; text-align: center; width: 88%; margin: 8px auto 0; }
.affiliations span { display: inline-block; margin: 0 4px; }
.tagline { max-width: 840px; margin: 14px auto 0; text-align: center; color: #4d4f55; }

.paper-btn-parent { display: flex; justify-content: center; flex-wrap: wrap; gap: 8px; margin: 16px 0 10px; }
.paper-btn { position: relative; text-align: center; display: inline-block; margin: 0; padding: 8px 12px; border: 0; outline: none; border-radius: 3px; background-color: var(--accent); color: #ffffff !important; font-size: 18px; min-width: 104px; font-weight: 600; }
.paper-btn:hover, .paper-btn:focus { opacity: 0.86; color: #ffffff !important; text-decoration: none; }
.paper-btn.disabled { background-color: #969696; cursor: default; }

.math { font-family: Georgia, "Times New Roman", serif; }
.kicker { display: inline-flex; gap: 6px; align-items: center; padding: 4px 9px; border-radius: 999px; background: var(--accent-soft); color: var(--accent-dark); font-weight: 600; font-size: 14px; margin-bottom: 8px; }

.takeaway-grid, .metric-grid, .method-grid, .tree-panel, .comparison-grid, .video-comparison-grid, .figure-grid { display: grid; gap: 12px; }
.takeaway-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); margin: 16px 0 8px; }
.method-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); margin-top: 12px; }
.metric-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); margin: 16px 0; }
.tree-panel { grid-template-columns: repeat(2, minmax(0, 1fr)); align-items: start; }
.comparison-grid, .video-comparison-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); margin-top: 12px; }
.figure-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); align-items: start; }

.card, .metric-card, .method-card, details, .notice, .comparison-viewer, .video-comparison-viewer, .tree-explorer, .tree-slider-card, .tree-gif-card {
  border: 1px solid var(--line);
  background: var(--panel);
  border-radius: 7px;
}
.card, .method-card { padding: 13px 14px; }
.method-card.emphasis { background: linear-gradient(180deg, #ffffff 0%, var(--accent-soft) 100%); border-color: #cfc8ff; }
.card strong, .method-card strong { font-weight: 700; }

.metric-card { padding: 14px; background: #ffffff; box-shadow: 0 8px 18px rgba(48, 42, 92, 0.06); }
.metric-card .metric-number { display: block; font-size: 31px; font-weight: 700; line-height: 1.05; color: var(--accent-dark); }
.metric-card .metric-label { display: block; font-size: 14px; font-weight: 600; color: #393b3e; margin-top: 4px; }
.metric-card .metric-note { display: block; color: var(--muted); font-size: 14px; margin-top: 6px; }

.notice { padding: 10px 12px; margin: 12px 0; color: #53565c; background: #fffdf7; border-color: #ead9aa; }
.notice strong { color: #2e3034; }

button, input { font: inherit; }
button { border: 1px solid #bbbbbb; border-radius: 4px; background: #ffffff; color: #333333; padding: 6px 10px; cursor: pointer; }
button:hover, button:focus { background: #eeeeee; }
button.primary { background: var(--accent); border-color: var(--accent); color: white; font-weight: 600; }
button.primary:hover, button.primary:focus { background: var(--accent-dark); }
.viewer-controls, .slider-controls, .gallery-controls, .video-gallery-controls, .tree-root-controls { display: flex; align-items: center; justify-content: center; gap: 8px; flex-wrap: wrap; margin-top: 10px; }
.viewer-controls input[type="range"], .slider-controls input[type="range"], .gallery-controls input[type="range"], .video-gallery-controls input[type="range"], .tree-root-controls input[type="range"] { width: min(340px, 70vw); }

.tree-gif-card, .tree-slider-card, .tree-explorer, .comparison-viewer, .video-comparison-viewer { padding: 13px; }
.tree-gif-card img, .tree-slider-card img { width: 100%; border: 1px solid #e7e7e7; border-radius: 6px; background: #ffffff; }
.frame-label { display: inline-block; padding: 4px 8px; border-radius: 999px; background: var(--accent-soft); color: var(--accent-dark); font-weight: 600; font-size: 14px; margin-top: 4px; }
#tree-frame-caption { min-height: 42px; color: var(--muted); font-size: 15px; text-align: center; }

.tree-explorer { margin-top: 14px; }
.tree-root-preview { display: grid; grid-template-columns: 190px 1fr; gap: 14px; align-items: start; margin: 12px 0; }
.tree-root-preview img, .selected-child img { border: 1px solid #dddddd; border-radius: 6px; background: #ffffff; width: 100%; }
.child-grid { display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 8px; margin-top: 10px; }
.child-card { border: 1px solid #dddddd; border-radius: 6px; background: #ffffff; padding: 6px; cursor: pointer; text-align: left; }
.child-card:hover, .child-card:focus { border-color: var(--accent); outline: none; }
.child-card.active { border: 3px solid var(--accent); padding: 4px; background: #fbfaff; }
.child-card img { display: block; width: 100%; border-radius: 4px; }
.child-card span { display: block; font-size: 12px; color: #4d4f55; margin-top: 4px; line-height: 1.2; }
.selected-child { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; align-items: start; margin-top: 14px; }
.selected-child figure { margin: 0; }

.example-title-row { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; flex-wrap: wrap; }
.badges { display: flex; flex-wrap: wrap; gap: 6px; margin: 8px 0; }
.badge { display: inline-block; padding: 3px 7px; border-radius: 999px; background: var(--green-soft); color: var(--green); font-size: 13px; font-weight: 600; }
.badge.score { background: var(--orange-soft); color: #b75a12; }
.comparison-grid figure { margin: 0; padding: 10px; border: 1px solid #dddddd; border-radius: 6px; background: #ffffff; }
.comparison-grid figure.winner { border-color: var(--accent); box-shadow: inset 0 0 0 2px var(--accent); }
.comparison-grid img { border-radius: 4px; background: #ffffff; }
.comparison-grid figcaption { font-weight: 600; color: #333333; }

.video-prompt { margin: 10px 0 8px; padding: 11px 13px; border: 1px solid #dcd7ff; border-left: 4px solid var(--accent); border-radius: 6px; background: linear-gradient(90deg, var(--accent-soft) 0%, #ffffff 72%); }
.video-prompt p { margin: 3px 0 0; line-height: 1.42; }
.prompt-label { display: block; color: var(--accent-dark); font-size: 13px; font-weight: 700; letter-spacing: 0.06em; text-transform: uppercase; }
.video-gallery-controls { margin: 12px 0 2px; }
.video-comparison-grid figure { margin: 0; padding: 10px; border: 1px solid #dddddd; border-radius: 6px; background: #ffffff; }
.video-comparison-grid figure.winner { border-color: var(--accent); box-shadow: inset 0 0 0 2px var(--accent); }
.video-comparison-grid video { display: block; width: 100%; aspect-ratio: 3 / 2; border-radius: 4px; background: #111111; object-fit: cover; }
.video-comparison-grid video:focus-visible { outline: 3px solid var(--accent); outline-offset: 2px; }
.video-comparison-grid figcaption { font-weight: 600; color: #333333; }

.table-wrap { width: 100%; overflow-x: auto; margin: 12px 0; background: #ffffff; border: 1px solid #dddddd; }
table { width: 100%; border-collapse: collapse; font-size: 14.5px; }
th, td { padding: 7px 8px; border-bottom: 1px solid #e8e8e8; text-align: left; white-space: nowrap; }
th { font-weight: 600; background: #f2f2f2; }
tr.highlight th, tr.highlight td { background: #eef1ff; font-weight: 600; }
tr.subtle td { color: #666666; }
details { padding: 10px 12px; margin-top: 10px; }
summary { cursor: pointer; font-weight: 600; color: var(--accent); }

.inline-steps { counter-reset: step; list-style: none; padding: 0; margin: 12px 0; display: grid; gap: 8px; }
.inline-steps li { position: relative; padding: 10px 12px 10px 42px; background: #ffffff; border: 1px solid #e6e6e6; border-radius: 6px; }
.inline-steps li::before { counter-increment: step; content: counter(step); position: absolute; left: 12px; top: 10px; width: 22px; height: 22px; border-radius: 50%; background: var(--accent); color: white; text-align: center; font-weight: 700; line-height: 22px; font-size: 13px; }

footer { margin: 40px 0 28px; padding-top: 14px; border-top: 1px solid #dddddd; color: #666666; text-align: center; font-size: 15px; }
.hidden { display: none !important; }

@media screen and (max-width: 800px) {
  .takeaway-grid, .metric-grid, .method-grid, .tree-panel, .comparison-grid, .video-comparison-grid, .figure-grid, .selected-child { grid-template-columns: 1fr; }
  .child-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .tree-root-preview { grid-template-columns: 1fr; }
}
@media screen and (max-width: 620px) {
  body { font-size: 16px; }
  h1 { font-size: 32px; }
  h2 { font-size: 1.45em; }
  .author-row-new a, .author-row-new span { font-size: 18px; }
  .affiliations { width: 100%; font-size: 16px; }
  section { margin: 28px 0; }
  .child-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .video-gallery-controls input[type="range"] { width: calc(100% - 102px); }
}

/* Tree figure refresh: larger text, one-column animation, and a real branch diagram. */
.tree-panel { grid-template-columns: 1fr; gap: 16px; }
.tree-gif-card, .tree-slider-card, .tree-explorer, .comparison-viewer, .video-comparison-viewer { padding: 18px; }
.tree-slider-card h3, .tree-gif-card h3, .tree-explorer h3 { font-size: 1.2em; margin-top: 0; }
.tree-gif-card img, .tree-slider-card img { border-radius: 10px; border-color: #deddf0; }
.tree-slider-main img { width: 100%; }
.tree-gif-main img { width: min(100%, 820px); display: block; margin: 0 auto; }
.frame-label { font-size: 16px; padding: 5px 10px; }
#tree-frame-caption { min-height: 34px; font-size: 17px; }
.compact-notice { font-size: 15.5px; line-height: 1.35; }
.tree-explorer-intro { color: var(--muted); font-size: 17px; margin-bottom: 12px; }
.tree-root-controls input[type="range"] { width: min(430px, 72vw); }

.branch-tree {
  position: relative;
  display: grid;
  grid-template-columns: minmax(170px, 0.78fr) minmax(360px, 1.45fr) minmax(220px, 0.9fr);
  gap: 28px;
  align-items: center;
  padding: 22px;
  margin-top: 16px;
  overflow: hidden;
  background: #ffffff;
  border: 1px solid #deddf0;
  border-radius: 12px;
  box-shadow: inset 0 0 0 1px rgba(90, 75, 194, 0.03);
}
.tree-lines {
  position: absolute;
  inset: 0;
  z-index: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}
.tree-column { position: relative; z-index: 1; min-width: 0; }
.tree-column-heading {
  color: var(--accent-dark);
  font-weight: 700;
  font-size: 16.5px;
  margin-bottom: 9px;
  text-align: center;
}
.tree-node {
  background: #ffffff;
  border: 1px solid #dedede;
  border-radius: 10px;
  padding: 10px;
  box-shadow: 0 8px 18px rgba(48, 42, 92, 0.08);
}
.root-node { border: 3px solid var(--accent); }
.root-node img, .final-node img, .branch-child-grid .child-card img {
  display: block;
  width: 100%;
  border-radius: 8px;
  background: #fafafa;
}
.root-node strong, .root-node span { display: block; }
#tree-root-title { margin-top: 8px; font-size: 20px; line-height: 1.15; }
#tree-root-meta { color: var(--muted); font-size: 16px; margin-top: 2px; }
.tree-node-note, .selected-continuation {
  color: var(--muted);
  font-size: 16px;
  line-height: 1.35;
  text-align: center;
  margin-top: 10px;
}
.final-node { margin: 0; border: 3px solid var(--accent); }
.final-node figcaption { font-size: 16px; font-weight: 700; color: #333333; margin-bottom: 0; }
.selected-continuation {
  background: var(--accent-soft);
  color: var(--accent-dark);
  border-radius: 8px;
  padding: 8px 10px;
  font-weight: 600;
}
.branch-child-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin: 0;
}
.branch-child-grid .child-card {
  position: relative;
  border: 1px solid #dddddd;
  border-radius: 10px;
  background: #ffffff;
  padding: 9px;
  text-align: left;
  box-shadow: 0 6px 14px rgba(48, 42, 92, 0.05);
}
.branch-child-grid .child-card:hover, .branch-child-grid .child-card:focus {
  border-color: var(--accent);
  outline: none;
  box-shadow: 0 8px 18px rgba(90, 75, 194, 0.13);
}
.branch-child-grid .child-card.active {
  border: 3px solid var(--accent);
  padding: 7px;
  background: #fbfaff;
}
.branch-child-grid .child-title {
  display: block;
  color: #303238;
  font-size: 16px;
  font-weight: 700;
  margin-top: 7px;
  line-height: 1.18;
}
.branch-child-grid .child-meta {
  display: block;
  color: var(--muted);
  font-size: 14.5px;
  margin-top: 2px;
  line-height: 1.2;
}

@media screen and (max-width: 860px) {
  .branch-tree { grid-template-columns: 1fr; gap: 18px; }
  .tree-lines { display: none; }
  .branch-child-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}
@media screen and (max-width: 520px) {
  .branch-child-grid { grid-template-columns: 1fr; }
  .tree-gif-card, .tree-slider-card, .tree-explorer, .comparison-viewer, .video-comparison-viewer { padding: 13px; }
}
.tree-line-path {
  fill: none;
  stroke: #aeb1bb;
  stroke-width: 2.6;
  stroke-linecap: round;
  opacity: 0.72;
}
.tree-line-path.active {
  stroke: var(--accent);
  stroke-width: 4.2;
  opacity: 1;
}