/* ============================================================
   DIMO — Diverse 3D Motion Generation for Arbitrary Objects
   Concept: one input → diverse trajectories sampled from a
   continuous motion latent space (blue → violet → pink).
   Dark "latent space" hero, light "paper" body. No JS.
   ============================================================ */

/* ---------- Design tokens ---------- */
:root {
  /* Dark hero */
  --space: #0B0E14;
  --space-2: #11151F;
  --on-space: #F4F6FA;
  --on-space-mute: #9AA3B2;
  --hairline-dark: rgba(255, 255, 255, 0.12);

  /* Light body */
  --paper: #FFFFFF;
  --paper-2: #F5F6F8;
  --ink: #0E1320;
  --ink-soft: #39414F;
  --mute: #6B7280;
  --line: #E6E8EC;

  /* Latent-space spectrum */
  --blue: #3B82F6;
  --violet: #8B5CF6;
  --pink: #FF5C8A;
  --spectrum: linear-gradient(90deg, var(--blue), var(--violet), var(--pink));

  --radius: 14px;
  --container: 1020px;
  --reading: 760px;

  --display: "Space Grotesk", system-ui, sans-serif;
  --body: "Inter", system-ui, sans-serif;
  --serif: "Newsreader", Georgia, "Times New Roman", serif;
  --mono: "Space Mono", ui-monospace, monospace;
}

/* ---------- Reset / base ---------- */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  /* Dark behind the page so overscroll at the top never flashes white. */
  background: var(--space);
}

body {
  margin: 0;
  font-family: var(--body);
  font-size: 17px;
  line-height: 1.7;
  color: var(--ink);
  background: var(--paper);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img,
video {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--violet);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

::selection {
  background: rgba(139, 92, 246, 0.22);
}

:focus-visible {
  outline: 2px solid var(--violet);
  outline-offset: 3px;
  border-radius: 4px;
}

/* Spectrum hairline framing the very top of the page. */
body::before {
  content: "";
  display: block;
  height: 3px;
  background: var(--spectrum);
}

/* ---------- Layout ---------- */
.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 52px 0;
}

/* Alternating tint separates sections; no border needed between them. */
.section--alt {
  background: var(--paper-2);
}

.prose {
  max-width: 100%;
}

.prose p {
  font-family: var(--serif);
  font-size: 1.18rem;
  line-height: 1.72;
  color: #2B3340;
  margin: 0;
  text-wrap: pretty;
}

.prose b,
.prose strong {
  color: var(--ink);
  font-weight: 600;
}

/* ---------- Section headings ---------- */
.kicker {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--mute);
  margin: 0 0 10px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.kicker::before {
  content: "";
  width: 22px;
  height: 2px;
  background: var(--spectrum);
}

.section-title {
  font-family: var(--display);
  font-weight: 700;
  font-size: clamp(1.6rem, 3.2vw, 2.15rem);
  letter-spacing: -0.02em;
  line-height: 1.1;
  margin: 0 0 24px;
}

/* ============================================================
   Hero — the latent space
   ============================================================ */
.hero {
  background:
    radial-gradient(900px 520px at 78% 12%, rgba(139, 92, 246, 0.22), transparent 60%),
    radial-gradient(700px 480px at 96% 90%, rgba(255, 92, 138, 0.16), transparent 60%),
    radial-gradient(700px 520px at 4% 20%, rgba(59, 130, 246, 0.16), transparent 60%),
    var(--space);
  color: var(--on-space);
  overflow: hidden;
  /* Fill the first screen so the landing view is entirely dark. */
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  align-items: center;
}

.hero > .container {
  width: 100%;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1.22fr 0.78fr;
  gap: 40px;
  align-items: center;
  padding: 56px 0;
}

/* Give the copy room for a single-line author list, then push the
   signature right into the gutter so it keeps presence. */
.hero__figure {
  transform: translateX(34px) scale(1.18);
  transform-origin: right center;
}

.hero__eyebrow {
  font-family: var(--mono);
  font-size: 0.82rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--on-space);
  margin: 0 0 22px;
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 7px 14px 7px 12px;
  border: 1px solid var(--hairline-dark);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.04);
}

.hero__eyebrow .dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--pink);
  box-shadow: 0 0 12px var(--pink);
}

/* The "Highlight" distinction carries the accent. */
.hero__eyebrow-hl {
  background: linear-gradient(90deg, var(--violet), var(--pink));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  font-weight: 700;
}

.hero__title {
  font-family: var(--display);
  font-weight: 700;
  font-size: clamp(2.3rem, 4.4vw, 3.45rem);
  line-height: 1.06;
  letter-spacing: -0.03em;
  margin: 0 0 22px;
}

/* Each phrase sits on its own line so wrapping never orphans a word. */
.hero__title .hero__name,
.hero__title .hero__plain,
.hero__title .word {
  display: block;
}

/* The project name anchors the hero as a wordmark. */
.hero__title .hero__name {
  font-size: 1.5em;
  line-height: 0.95;
  letter-spacing: -0.045em;
  margin-bottom: 0.18em;
}

/* The descriptive phrases read as a subordinate subtitle. */
.hero__title .hero__plain,
.hero__title .word {
  font-size: 0.82em;
  line-height: 1.1;
}

.hero__title .word {
  background: var(--spectrum);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
  width: fit-content;
}

/* Editorial deck: the serif reading voice introduced up front. */
.hero__lede {
  font-family: var(--serif);
  font-style: italic;
  font-size: clamp(1.2rem, 1.9vw, 1.5rem);
  line-height: 1.45;
  color: var(--on-space);
  max-width: 34rem;
  margin: 0 0 30px;
  text-wrap: pretty;
}

.hero__authors {
  font-size: 0.92rem;
  line-height: 1.7;
  color: var(--on-space);
  margin: 0 0 6px;
}

.hero__authors a {
  color: var(--on-space);
  border-bottom: 1px solid var(--hairline-dark);
  text-decoration: none;
  transition: border-color 0.18s ease;
}

.hero__authors a:hover {
  border-color: var(--pink);
}

.hero__affil {
  font-family: var(--mono);
  font-size: 0.82rem;
  color: var(--on-space-mute);
  line-height: 1.7;
  margin: 0 0 30px;
}

.nowrap {
  white-space: nowrap;
}

/* ============================================================
   Side navigation — a vertical "trajectory" of section nodes
   sitting in the left gutter. Right-anchored so the labels
   always show yet stop with a clear gap before the content.
   ============================================================ */
.sidenav {
  position: fixed;
  top: 50%;
  /* Right edge sits this far to the left of the content column. */
  left: calc((100vw - var(--container)) / 2 - 88px);
  transform: translate(-100%, -50%);
  z-index: 50;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease;
}

.sidenav.is-visible {
  opacity: 1;
  pointer-events: auto;
}

.sidenav ul {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 11px;
}

/* The trajectory line linking the nodes. */
.sidenav ul::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 17px;
  bottom: 17px;
  width: 2px;
  background: var(--line);
  border-radius: 2px;
}

/* Spectrum progress fill — a sample travelling down the trajectory
   as far as the section currently in view (height set in nav.js). */
.sidenav ul::after {
  content: "";
  position: absolute;
  left: 5px;
  top: 17px;
  width: 2px;
  height: var(--nav-progress, 0px);
  background: linear-gradient(180deg, var(--blue), var(--violet), var(--pink));
  border-radius: 2px;
  transition: height 0.3s ease;
}

.sidenav a {
  position: relative;
  display: flex;
  align-items: center;
  gap: 15px;
  padding: 4px 0;
  text-decoration: none;
}

.sidenav a:hover {
  text-decoration: none;
}

/* Section node sitting on the track. */
.sidenav__mark {
  position: relative;
  z-index: 1;
  flex: none;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--paper);
  border: 2px solid var(--line);
  box-shadow: 0 0 0 5px var(--paper);
  transition: transform 0.22s ease, border-color 0.22s ease, background 0.22s ease, box-shadow 0.22s ease;
}

.sidenav__label {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.13em;
  text-transform: uppercase;
  color: var(--mute);
  white-space: nowrap;
  transition: color 0.22s ease;
}

.sidenav a:hover .sidenav__label,
.sidenav a:focus-visible .sidenav__label {
  color: var(--ink);
}

.sidenav a:hover .sidenav__mark,
.sidenav a:focus-visible .sidenav__mark {
  border-color: var(--violet);
}

/* Active section: a glowing keypoint on the trajectory. */
.sidenav a.is-active .sidenav__label {
  color: var(--ink);
}

.sidenav a.is-active .sidenav__mark {
  border-color: transparent;
  background: linear-gradient(135deg, var(--blue), var(--pink));
  box-shadow: 0 0 0 5px var(--paper), 0 0 12px rgba(139, 92, 246, 0.45);
  transform: scale(1.18);
}

/* Not enough gutter for a labelled rail — hide it. */
@media (max-width: 1480px) {
  .sidenav {
    display: none;
  }
}

/* ---------- Links / buttons ---------- */
.links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 9px;
  padding: 11px 17px;
  border-radius: 999px;
  font-family: var(--body);
  font-weight: 600;
  font-size: 0.95rem;
  border: 1px solid var(--hairline-dark);
  color: var(--on-space);
  background: rgba(255, 255, 255, 0.04);
  transition: transform 0.18s ease, background 0.18s ease, border-color 0.18s ease;
}

.btn:hover {
  text-decoration: none;
  transform: translateY(-2px);
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.28);
}

.btn i {
  font-size: 1.05em;
}

/* ============================================================
   Signature — keypoint trajectory field
   ============================================================ */
.field {
  width: 100%;
  height: auto;
  overflow: visible;
}

.field .traj {
  fill: none;
  stroke-width: 1.6;
  opacity: 0.55;
  stroke-linecap: round;
}

.field .origin {
  fill: none;
  stroke: var(--on-space);
  stroke-width: 1.8;
  opacity: 0.85;
}

.field .origin-core {
  fill: var(--on-space);
}

.field .field-label {
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  fill: #AEB6C4;
  text-transform: uppercase;
}

.field .field-label--decode {
  fill: #C9B6F0;
}

/* ---- Latent space: the manifold Z ---- */
.field .encode {
  fill: none;
  stroke: rgba(174, 182, 196, 0.45);
  stroke-width: 1.4;
  stroke-dasharray: 4 5;
  stroke-linecap: round;
}

/* Soft atmosphere so the manifold floats in latent space. */
.field .manifold-glow {
  fill: url(#manifoldGlow);
}

.field .manifold-surface {
  fill: url(#manifoldFill);
  stroke: rgba(186, 176, 255, 0.42);
  stroke-width: 1.3;
  stroke-linejoin: round;
}

/* Curved height-field mesh — the learned low-dimensional surface. */
.field .manifold-grid {
  fill: none;
  stroke: rgba(190, 198, 224, 0.24);
  stroke-width: 0.9;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.field .latent {
  fill: var(--on-space);
  filter: drop-shadow(0 0 7px var(--violet));
  animation: latent-pulse 3.2s ease-in-out infinite;
}

@keyframes latent-pulse {
  0%, 100% { opacity: 0.7; }
  50% { opacity: 1; }
}

.field .kp {
  filter: drop-shadow(0 0 6px currentColor);
}

.field .kp--lead {
  fill: var(--on-space);
}

.field .kp--trail {
  opacity: 0.35;
}

/* Skeletal "diverse motions" at the trajectory ends. */
.field .bone {
  fill: none;
  stroke: currentColor;
  stroke-width: 2.8;
  stroke-linecap: round;
  filter: drop-shadow(0 0 4px currentColor);
}

.field .skel-head {
  fill: none;
  stroke: currentColor;
  stroke-width: 2.5;
  filter: drop-shadow(0 0 4px currentColor);
}

.field .joint {
  fill: var(--on-space);
}

/* Pivot rotations resolve against viewBox coordinates. */
.field .limb {
  transform-box: view-box;
}

.field .skel.jump {
  transform-box: view-box;
  animation: skel-jump 1.15s ease-in-out infinite;
}

.field .skel.turn {
  transform-box: view-box;
  animation: skel-turn 3s ease-in-out infinite;
}

.field .kick {
  animation: skel-kick 1.3s cubic-bezier(0.5, 0, 0.3, 1) infinite;
}

.field .wave {
  animation: skel-wave 1.5s ease-in-out infinite;
}

.field .swingA {
  animation: skel-swing 1s ease-in-out infinite;
}

.field .swingB {
  animation: skel-swing 1s ease-in-out infinite reverse;
}

.field .legA {
  animation: skel-leg 1s ease-in-out infinite;
}

.field .legB {
  animation: skel-leg 1s ease-in-out infinite reverse;
}

@keyframes skel-wave {
  0%, 100% { transform: rotate(6deg); }
  50% { transform: rotate(-16deg); }
}

@keyframes skel-swing {
  0%, 100% { transform: rotate(24deg); }
  50% { transform: rotate(-24deg); }
}

@keyframes skel-leg {
  0%, 100% { transform: rotate(-16deg); }
  50% { transform: rotate(16deg); }
}

@keyframes skel-jump {
  0%, 100% { transform: translateY(0); }
  35% { transform: translateY(-8px); }
  65% { transform: translateY(-2px); }
}

@keyframes skel-kick {
  0%, 100% { transform: rotate(8deg); }
  45% { transform: rotate(-64deg); }
  60% { transform: rotate(-58deg); }
}

/* Flip across the vertical axis reads as the figure turning around. */
@keyframes skel-turn {
  0%, 12% { transform: scaleX(1); }
  50%, 62% { transform: scaleX(-1); }
  100% { transform: scaleX(1); }
}

/* ============================================================
   Media (videos, figures)
   ============================================================ */
.media {
  position: relative;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--paper-2);
  border: 1px solid var(--line);
  box-shadow: 0 1px 2px rgba(14, 19, 32, 0.04);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.media:hover {
  transform: translateY(-3px);
  box-shadow: 0 18px 40px rgba(14, 19, 32, 0.12);
}

.media + .media {
  margin-top: 20px;
}

.media video,
.media img {
  width: 100%;
  display: block;
}

.media--embed {
  aspect-ratio: 16 / 9;
}

.media--embed iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.caption {
  font-family: var(--mono);
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  color: var(--mute);
  margin: 18px 0 0;
}

.figure {
  margin: 0 0 22px;
}

/* ============================================================
   Citation
   ============================================================ */
.cite {
  margin: 0;
  background: var(--space);
  color: var(--on-space);
  border-radius: var(--radius);
  padding: 26px 28px;
  overflow-x: auto;
  border: 1px solid var(--hairline-dark);
}

.cite code {
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.7;
  white-space: pre;
  color: var(--on-space);
}

/* ---------- Footer ---------- */
.footer {
  padding: 36px 0 56px;
  border-top: 1px solid var(--line);
}

.footer p {
  font-family: var(--mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  color: var(--mute);
  margin: 0;
}

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 860px) {
  .hero__inner {
    grid-template-columns: 1fr;
    gap: 36px;
    padding: 72px 0 64px;
  }

  .hero__figure {
    order: 2;
    max-width: 520px;
    transform: none;
  }
}

@media (max-width: 520px) {
  .links {
    gap: 9px;
  }

  .btn {
    padding: 10px 16px;
    font-size: 0.9rem;
  }
}

/* ============================================================
   Reduced motion — keep the static trajectory composition,
   drop the traveling keypoints.
   ============================================================ */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .field .kp {
    display: none;
  }

  .field .skel,
  .field .limb,
  .field .latent {
    animation: none !important;
  }

  .media,
  .btn,
  .sidenav__mark,
  .sidenav__label {
    transition: none;
  }

  .sidenav ul::after {
    transition: none;
  }
}