static/style.css

/* ToolTree project page — hand-written, zero external dependencies. */

:root {
  --ink: #1e293b;
  --ink-strong: #0f172a;
  --muted: #64748b;
  --accent: #6d28d9;
  --accent-dark: #5b21b6;
  --accent-soft: #ede9fe;
  --accent-faint: #f5f3ff;
  --border: #e2e8f0;
  --bg-alt: #f8fafc;
  --card-shadow: 0 1px 2px rgba(15, 23, 42, 0.05), 0 4px 14px rgba(15, 23, 42, 0.06);
  --card-shadow-lift: 0 2px 4px rgba(15, 23, 42, 0.06), 0 10px 28px rgba(15, 23, 42, 0.12);
  --nav-h: 52px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--nav-h) + 12px);
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
    Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  font-size: 17px;
  line-height: 1.65;
  color: var(--ink);
  background: #ffffff;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body.no-scroll { overflow: hidden; }

.container {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
}

section { padding: 56px 0; }
section.section-alt { background: var(--bg-alt); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }

h2 {
  font-size: 1.75rem;
  line-height: 1.25;
  margin: 0 0 20px;
  color: var(--ink-strong);
  letter-spacing: -0.01em;
  text-align: center;
}

h3 {
  font-size: 1.15rem;
  margin: 32px 0 10px;
  color: var(--ink-strong);
}

p { margin: 0 0 16px; }
a { color: var(--accent); }
a:hover { color: var(--accent-dark); }

/* ---------- Sticky section nav ---------- */

.topnav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 60;
  display: none;
  transform: translateY(-100%);
  background: rgba(255, 255, 255, 0.92);
  -webkit-backdrop-filter: blur(8px);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}
html.js .topnav { display: block; }
.topnav.visible {
  transform: translateY(0);
  box-shadow: 0 4px 18px rgba(15, 23, 42, 0.06);
}

.topnav-inner {
  max-width: 960px;
  margin: 0 auto;
  padding: 0 24px;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  gap: 18px;
}

.topnav-brand {
  font-weight: 800;
  font-size: 1.02rem;
  letter-spacing: -0.01em;
  color: var(--accent-dark);
  text-decoration: none;
  flex: none;
}
.topnav-brand:hover { color: var(--accent); }

.topnav-links {
  display: flex;
  gap: 2px;
  margin-left: auto;
  overflow-x: auto;
  scrollbar-width: none;
}
.topnav-links::-webkit-scrollbar { display: none; }

.topnav-links a {
  color: var(--muted);
  text-decoration: none;
  font-size: 0.88rem;
  font-weight: 500;
  padding: 6px 10px;
  border-radius: 8px;
  white-space: nowrap;
  transition: color 0.15s ease, background-color 0.15s ease;
}
.topnav-links a:hover {
  color: var(--accent-dark);
  background: var(--accent-faint);
}

/* ---------- Hero ---------- */

.hero {
  position: relative;
  overflow: hidden;
  padding: 84px 0 60px;
  text-align: center;
  background:
    radial-gradient(1100px 480px at 50% -140px, var(--accent-faint), rgba(255, 255, 255, 0) 72%),
    radial-gradient(700px 340px at 88% -160px, #eef2ff, rgba(255, 255, 255, 0) 70%),
    #ffffff;
}

/* Faint dot-grid, fading out below the fold — pure CSS, no assets. */
.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(15, 23, 42, 0.045) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(15, 23, 42, 0.045) 1px, transparent 1px);
  background-size: 34px 34px;
  -webkit-mask-image: radial-gradient(820px 460px at 50% -60px, rgba(0, 0, 0, 0.85), transparent 78%);
  mask-image: radial-gradient(820px 460px at 50% -60px, rgba(0, 0, 0, 0.85), transparent 78%);
  pointer-events: none;
}

.hero .container { position: relative; }

.hero h1 {
  font-size: clamp(1.7rem, 4vw, 2.6rem);
  line-height: 1.18;
  letter-spacing: -0.022em;
  font-weight: 800;
  margin: 0 auto 28px;
  max-width: 880px;
  color: var(--ink-strong);
  text-wrap: balance;
}

.hero h1 .hero-name { color: var(--accent); }
@supports ((-webkit-background-clip: text) or (background-clip: text)) {
  .hero h1 .hero-name {
    background: linear-gradient(115deg, #7c3aed 20%, #4f46e5 80%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
  }
}

.authors {
  font-size: 1.08rem;
  font-weight: 500;
  margin: 0 auto 6px;
  max-width: 820px;
  color: var(--ink);
}

.affiliation {
  font-size: 0.97rem;
  color: var(--muted);
  margin-bottom: 0;
}

.venue { margin: 18px 0 30px; }

.venue-chip {
  display: inline-block;
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--accent-dark);
  background: var(--accent-soft);
  border: 1px solid #ddd6fe;
  border-radius: 999px;
  padding: 5px 16px;
}

.button-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}

/* ---------- Buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 999px;
  background: var(--ink-strong);
  color: #ffffff;
  text-decoration: none;
  font-size: 0.96rem;
  font-weight: 600;
  border: 1px solid var(--ink-strong);
  transition: background-color 0.18s ease, color 0.18s ease, border-color 0.18s ease,
    transform 0.18s ease, box-shadow 0.18s ease;
}
.btn:hover {
  background: #334155;
  border-color: #334155;
  color: #ffffff;
  transform: translateY(-2px);
  box-shadow: 0 6px 16px rgba(15, 23, 42, 0.16);
}
.btn:active { transform: translateY(0); box-shadow: none; }
.btn:focus-visible { outline: 3px solid var(--accent-soft); outline-offset: 2px; }

.btn .btn-ico { width: 15px; height: 15px; flex: none; opacity: 0.9; }

.btn-accent { background: var(--accent); border-color: var(--accent); }
.btn-accent:hover { background: var(--accent-dark); border-color: var(--accent-dark); }

.btn-outline {
  background: #ffffff;
  color: var(--accent-dark);
  border-color: #c4b5fd;
}
.btn-outline:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
  box-shadow: 0 6px 16px rgba(109, 40, 217, 0.25);
}

.btn-ghost {
  background: rgba(255, 255, 255, 0.7);
  color: var(--ink);
  border-color: var(--border);
}
.btn-ghost:hover {
  background: #ffffff;
  border-color: #cbd5e1;
  color: var(--ink-strong);
  box-shadow: 0 6px 16px rgba(15, 23, 42, 0.1);
}

/* ---------- Scroll-reveal (JS adds .js to <html>; no JS = always visible) ---------- */

html.js .reveal {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.55s ease, transform 0.55s ease;
}
html.js .reveal.revealed {
  opacity: 1;
  transform: none;
}

/* Staggered grids: the container fades, children lift in one after another. */
html.js .reveal.stagger { transform: none; }
html.js .reveal.stagger > * {
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.5s ease, transform 0.5s ease, box-shadow 0.2s ease, border-color 0.2s ease;
}
html.js .reveal.stagger.revealed > * { opacity: 1; transform: none; }
html.js .reveal.stagger.revealed > :nth-child(2) {
  transition: opacity 0.5s ease 0.12s, transform 0.5s ease 0.12s, box-shadow 0.2s ease 0s, border-color 0.2s ease 0s;
}
html.js .reveal.stagger.revealed > :nth-child(3) {
  transition: opacity 0.5s ease 0.24s, transform 0.5s ease 0.24s, box-shadow 0.2s ease 0s, border-color 0.2s ease 0s;
}

/* ---------- Metric callout cards ---------- */

.metrics { padding: 8px 0 48px; }

.metric-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.metric-card {
  background: #ffffff;
  border: 1px solid var(--border);
  border-top: 3px solid var(--accent);
  border-radius: 14px;
  padding: 26px 22px 22px;
  text-align: center;
  box-shadow: var(--card-shadow);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
.metric-card:hover { box-shadow: var(--card-shadow-lift); border-color: #cbd5e1; border-top-color: var(--accent); }

.metric-value {
  font-size: 2.6rem;
  font-weight: 700;
  line-height: 1.1;
  color: var(--accent);
  letter-spacing: -0.02em;
}

.metric-label {
  margin-top: 10px;
  font-size: 0.96rem;
  color: var(--ink);
}

.metric-sub {
  margin-top: 6px;
  font-size: 0.86rem;
  color: var(--muted);
}

/* ---------- Showcase (the architecture figure inside Method) ---------- */
/* Breaks out of the 960px column, centered on the viewport — width/margin only,
   no transform (transform belongs to the .reveal animation). */
figure.paper-figure.figure-hero {
  width: min(1160px, calc(100vw - 48px));
  margin-left: calc((100% - min(1160px, calc(100vw - 48px))) / 2);
}
figure.paper-figure.figure-hero img {
  max-width: 100%;
  padding: 14px;
  border-radius: 18px;
  border-color: #e2e8f0;
  box-shadow: 0 10px 32px rgba(15, 23, 42, 0.10), 0 2px 8px rgba(15, 23, 42, 0.06);
}
figure.paper-figure.figure-hero img:hover {
  box-shadow: 0 14px 40px rgba(109, 40, 217, 0.16), 0 3px 10px rgba(15, 23, 42, 0.08);
  border-color: #c4b5fd;
}
figure.paper-figure.figure-hero figcaption { max-width: 900px; }

/* ---------- Figure 3 band (between abstract and method) ---------- */
.fig3-band { padding: 40px 0; }
.fig3-band figure.paper-figure { margin-top: 0; }

/* ---------- Figure 1 beside the abstract (unused fallback) ---------- */
.abstract-grid {
  display: grid;
  grid-template-columns: 1.15fr 0.62fr;
  gap: 30px;
  align-items: center;
}
.abstract-grid .abstract-card { max-width: none; margin: 0; }
figure.paper-figure.figure-side { margin: 0; }
figure.paper-figure.figure-side img { max-width: 100%; padding: 8px; }
figure.paper-figure.figure-side figcaption { font-size: 0.8rem; margin-top: 10px; }
@media (max-width: 880px) {
  .abstract-grid { grid-template-columns: 1fr; }
  figure.paper-figure.figure-side img { max-width: 420px; }
}

/* ---------- Abstract ---------- */

.abstract-card {
  max-width: 800px;
  margin: 0 auto;
  background: var(--bg-alt, #f8fafc);
  border: 1px solid var(--border);
  border-left: 4px solid #6d28d9;
  border-radius: 14px;
  padding: 26px 32px;
}
.abstract-text {
  margin: 0;
  text-align: justify;
  hyphens: auto;
  line-height: 1.72;
}
@media (max-width: 640px) {
  .abstract-card { padding: 18px 18px; }
  .abstract-text { text-align: left; }
}

/* ---------- Paper figures ---------- */

figure.paper-figure {
  margin: 26px auto 10px;
  text-align: center;
}
figure.paper-figure img {
  width: 100%;
  max-width: 960px;
  height: auto;
  display: block;
  margin: 0 auto;
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 10px;
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
figure.paper-figure img:hover { box-shadow: var(--card-shadow-lift); border-color: #cbd5e1; }
html.js figure.paper-figure img,
html.js .case-figure img { cursor: zoom-in; }
figure.paper-figure.figure-narrow img { max-width: 560px; }
figure.paper-figure.figure-medium img { max-width: 680px; }
figure.paper-figure .figure-stack img + img { margin-top: 14px; }
figure.paper-figure figcaption {
  font-size: 0.88rem;
  color: var(--muted);
  text-align: center;
  max-width: 820px;
  margin: 12px auto 0;
}
figure.paper-figure figcaption .fig-tag {
  font-weight: 600;
  color: var(--ink);
}

.mech-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 34px;
}

.mech-card {
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 22px;
  box-shadow: var(--card-shadow);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
.mech-card:hover { box-shadow: var(--card-shadow-lift); border-color: #cbd5e1; }

.mech-card h3 {
  margin: 0 0 10px;
  font-size: 1.04rem;
  color: var(--accent-dark);
}

.mech-card p { margin: 0; font-size: 0.94rem; color: var(--ink); }

.mech-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  margin-bottom: 12px;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent-dark);
  font-weight: 700;
  font-size: 0.9rem;
}

.gradient-free {
  margin: 30px auto 0;
  max-width: 820px;
  text-align: center;
  font-size: 0.98rem;
  background: var(--accent-faint);
  border: 1px solid var(--accent-soft);
  border-radius: 10px;
  padding: 12px 18px;
  color: var(--ink);
}

/* ---------- Tables ---------- */

.table-wrap { overflow-x: auto; margin: 20px 0 6px; }

table.results {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.94rem;
  background: #ffffff;
}

table.results caption {
  caption-side: top;
  text-align: left;
  font-weight: 600;
  font-size: 1.02rem;
  color: var(--ink-strong);
  padding: 0 0 10px;
}

table.results th, table.results td {
  padding: 8px 12px;
  text-align: right;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

table.results th:first-child, table.results td:first-child { text-align: left; }

table.results thead th {
  border-bottom: 2px solid var(--ink-strong);
  color: var(--ink-strong);
  font-weight: 600;
}

table.results tbody tr { transition: background-color 0.15s ease; }
table.results tbody tr:hover td { background: var(--bg-alt); }

table.results tr.ours td {
  background: var(--accent-soft);
  font-weight: 700;
  color: var(--accent-dark);
}
table.results tr.ours:hover td { background: var(--accent-soft); }
table.results tr.ours td:first-child { border-left: 3px solid var(--accent); }

.table-note {
  font-size: 0.86rem;
  color: var(--muted);
  margin: 8px 0 28px;
}

.takeaway {
  font-size: 0.95rem;
  margin: 10px 0 30px;
  padding: 10px 16px;
  background: var(--accent-faint);
  border-left: 3px solid var(--accent);
  border-radius: 0 8px 8px 0;
}

.ablation-block { margin-bottom: 8px; }

.block-title {
  text-align: center;
  margin-top: 44px;
  font-size: 1.25rem;
}

.block-intro {
  max-width: 820px;
  margin: 0 auto 4px;
}

/* ---------- Efficiency & transfer ---------- */

.info-card {
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  box-shadow: var(--card-shadow);
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
.info-card:hover { box-shadow: var(--card-shadow-lift); border-color: #cbd5e1; }
.info-card h3 { margin: 0 0 10px; font-size: 1.08rem; }
.info-card p { margin: 0 0 10px; font-size: 0.96rem; }
.info-card p:last-child { margin-bottom: 0; }

.info-card-solo { max-width: 820px; margin: 18px auto 34px; }

/* ---------- Case study band ---------- */

.band-label {
  display: inline-block;
  font-size: 0.84rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: #92400e;
  background: #fef3c7;
  border: 1px solid #fde68a;
  border-radius: 999px;
  padding: 5px 14px;
  margin-bottom: 18px;
}

.case-figure { margin: 18px 0; text-align: center; }
.case-figure img {
  width: 100%;
  max-width: 860px;
  height: auto;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: #ffffff;
  transition: box-shadow 0.2s ease, border-color 0.2s ease;
}
.case-figure img:hover { box-shadow: var(--card-shadow-lift); border-color: #cbd5e1; }

.case-text { max-width: 820px; margin: 0 auto 22px; }

.case-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 18px;
}
.case-actions .aux-link { font-size: 0.95rem; }

#case-study { text-align: center; }
#case-study .case-text { text-align: left; }

/* ---------- Lightbox (created by JS on demand) ---------- */

.lightbox {
  position: fixed;
  inset: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 30px;
  background: rgba(15, 23, 42, 0.84);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s ease, visibility 0.2s ease;
  cursor: zoom-out;
}
.lightbox.open { opacity: 1; visibility: visible; }

.lightbox img {
  max-width: min(1200px, 100%);
  max-height: 92vh;
  width: auto;
  height: auto;
  background: #ffffff;
  border-radius: 10px;
  padding: 8px;
  box-shadow: 0 24px 70px rgba(0, 0, 0, 0.45);
}

.lightbox-close {
  position: absolute;
  top: 14px;
  right: 18px;
  width: 40px;
  height: 40px;
  border: 1px solid rgba(255, 255, 255, 0.35);
  border-radius: 50%;
  background: rgba(15, 23, 42, 0.5);
  color: #f1f5f9;
  font-size: 1.35rem;
  line-height: 1;
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
}
.lightbox-close:hover { background: rgba(51, 65, 85, 0.85); border-color: rgba(255, 255, 255, 0.6); }
.lightbox-close:focus-visible { outline: 3px solid var(--accent-soft); outline-offset: 2px; }

/* ---------- BibTeX ---------- */

.bibtex-box { position: relative; max-width: 860px; margin: 0 auto; }

.bibtex-box pre {
  background: #0f172a;
  color: #e2e8f0;
  border-radius: 14px;
  padding: 24px 26px;
  overflow-x: auto;
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
  font-size: 0.86rem;
  line-height: 1.55;
  margin: 0;
}

.copy-btn {
  position: absolute;
  top: 12px;
  right: 12px;
  background: #334155;
  color: #e2e8f0;
  border: 1px solid #475569;
  border-radius: 8px;
  padding: 6px 14px;
  font-size: 0.84rem;
  font-family: inherit;
  cursor: pointer;
  transition: background-color 0.15s ease;
}
.copy-btn:hover { background: #475569; }

/* ---------- Footer ---------- */

footer {
  border-top: 1px solid var(--border);
  padding: 30px 0 38px;
  text-align: center;
  font-size: 0.9rem;
  color: var(--muted);
}

/* ---------- Responsive ---------- */

@media (max-width: 760px) {
  section { padding: 42px 0; }
  .hero { padding: 60px 0 46px; }
  .metric-grid, .mech-grid { grid-template-columns: 1fr; }
  .metric-value { font-size: 2.2rem; }
  body { font-size: 16px; }
  .topnav-inner { gap: 12px; padding: 0 16px; }
}

/* ---------- Reduced motion: no animation, everything visible ---------- */

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  html.js .reveal,
  html.js .reveal.stagger > * {
    opacity: 1;
    transform: none;
  }
  *, *::before, *::after {
    transition: none !important;
    animation: none !important;
  }
  .btn:hover { transform: none; }
}

/* 4-card mechanism grid: 2x2 on desktop, single column on narrow screens.
   (Kept after the responsive block above so the narrow-screen override below
   must also live here — same specificity, source order decides.) */
.mech-grid.mech-grid-4 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 760px) {
  .mech-grid.mech-grid-4 { grid-template-columns: 1fr; }
}