:root {
  --bg: #f6f8fc;
  --bg-card: #ffffff;
  --bg-elevated: #eef2f9;
  --text: #1a2438;
  --text-muted: #5a6b85;
  --accent: #3b6fd9;
  --accent-2: #6b4fd4;
  --border: rgba(26, 36, 56, 0.1);
  --success: #0d9f6e;
  --shadow: 0 12px 40px rgba(26, 36, 56, 0.08);
  --radius: 16px;
  --font: "Inter", system-ui, -apple-system, sans-serif;
  --mono: "JetBrains Mono", ui-monospace, monospace;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(91, 141, 239, 0.12), transparent),
    radial-gradient(ellipse 60% 40% at 100% 0%, rgba(124, 92, 255, 0.06), transparent);
  pointer-events: none;
  z-index: -1;
}

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

.container {
  width: min(1200px, 92vw);
  margin: 0 auto;
}

/* Nav */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(12px);
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 0;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.nav-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: var(--text);
}

/* Paper hero */
.paper-hero {
  padding: 3.5rem 0 2rem;
  text-align: center;
}

.paper-title {
  font-size: clamp(1.65rem, 4.2vw, 2.75rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.25;
  margin-bottom: 1.75rem;
  color: var(--text);
  max-width: 920px;
  margin-left: auto;
  margin-right: auto;
}

.hf-dataset-link {
  display: inline-flex;
  align-items: center;
  gap: 0.85rem;
  padding: 0.65rem 1.1rem 0.65rem 0.85rem;
  margin-bottom: 2.5rem;
  background: linear-gradient(135deg, #fff9e6 0%, #fffdf5 100%);
  border: 1.5px solid #ffd21e;
  border-radius: 14px;
  box-shadow: 0 4px 20px rgba(255, 210, 30, 0.25);
  color: var(--text);
  text-decoration: none;
  transition: transform 0.2s, box-shadow 0.2s;
}

.hf-dataset-link:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(255, 210, 30, 0.35);
  color: var(--text);
}

.hf-dataset-link__icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  background: #ffd21e;
  border-radius: 10px;
}

.hf-dataset-link__icon img {
  display: block;
}

.hf-dataset-link__text {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  text-align: left;
  line-height: 1.3;
}

.hf-dataset-link__label {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
}

.hf-dataset-link__name {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text);
}

.hf-dataset-link__action {
  display: flex;
  align-items: center;
  justify-content: center;
  margin-left: 0.25rem;
  color: var(--accent);
}

.paper-figure {
  margin: 0 auto;
  max-width: 100%;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: calc(var(--radius) + 4px);
  padding: 1rem;
  box-shadow: var(--shadow);
}

.paper-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 8px;
}

.paper-figure figcaption {
  margin-top: 0.75rem;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* DestBench intro */
.destbench-intro {
  padding: 3rem 0 2rem;
  text-align: center;
  border-top: 1px solid var(--border);
  background: rgba(255, 255, 255, 0.6);
}

.destbench-title {
  font-size: 2rem;
  background: linear-gradient(135deg, #1a2438 0%, #3b6fd9 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.destbench-desc {
  margin-left: auto;
  margin-right: auto;
}

/* Hero stats (DestBench) */
.hero {
  padding: 5rem 0 4rem;
  text-align: center;
}

.hero-badge {
  display: inline-block;
  padding: 0.35rem 0.9rem;
  border-radius: 999px;
  background: rgba(91, 141, 239, 0.15);
  border: 1px solid rgba(91, 141, 239, 0.35);
  color: var(--accent);
  font-size: 0.8rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.5rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, #1a2438 0%, #3b6fd9 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero p {
  color: var(--text-muted);
  font-size: 1.15rem;
  max-width: 720px;
  margin: 0 auto 2rem;
}

.hero-stats {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  flex-wrap: wrap;
}

.hero-stat strong {
  display: block;
  font-size: 2rem;
  color: var(--text);
}

.hero-stat span {
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Sections */
section {
  padding: 4rem 0;
}

.section-title {
  font-size: 1.75rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  letter-spacing: -0.02em;
}

.section-subtitle {
  color: var(--text-muted);
  margin-bottom: 2rem;
  max-width: 680px;
}

/* Apps browser */
.apps-browser {
  display: grid;
  grid-template-columns: 1fr minmax(280px, 360px);
  gap: 1.5rem;
  align-items: start;
}

@media (max-width: 900px) {
  .apps-browser {
    grid-template-columns: 1fr;
  }
}

.app-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 1rem;
}

.app-card {
  appearance: none;
  font: inherit;
  color: inherit;
  cursor: pointer;
  width: 100%;
  background: #f4f7fc;
  border: 2px solid transparent;
  border-radius: var(--radius);
  padding: 1.25rem 1rem;
  text-align: center;
  transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.12);
}

.app-card:hover {
  transform: translateY(-2px);
  border-color: rgba(91, 141, 239, 0.55);
  box-shadow: 0 8px 24px rgba(91, 141, 239, 0.2);
}

.app-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(91, 141, 239, 0.35);
}

.app-card .logo-slot img {
  object-fit: contain;
}

.app-card .logo-slot {
  width: 48px;
  height: 48px;
  margin: 0 auto 0.75rem;
  position: relative;
}

.app-card .logo-slot img,
.app-card .logo-slot .fallback-logo {
  width: 48px;
  height: 48px;
  border-radius: 12px;
}

.app-card .logo-slot img[hidden],
.app-card .logo-slot .fallback-logo[hidden] {
  display: none !important;
}

.app-card .logo-slot .fallback-logo:not([hidden]) {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  font-weight: 700;
  font-size: 1.1rem;
  color: #fff;
}

.app-card h3 {
  font-size: 0.9rem;
  margin-bottom: 0.25rem;
  color: #1a2438;
}

.app-card .app-version,
.app-card .app-task-count {
  font-size: 0.75rem;
  color: #5a6b85;
}

/* Task panel */
.task-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  max-height: 520px;
  display: flex;
  flex-direction: column;
  position: sticky;
  top: 5rem;
}

.task-panel-header {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.5rem;
}

.panel-logo-wrap {
  position: relative;
  width: 36px;
  height: 36px;
  flex-shrink: 0;
}

.panel-placeholder-icon {
  display: block;
  border-radius: 8px;
}

.task-panel-header img,
.task-panel-header .fallback-logo {
  width: 36px;
  height: 36px;
  border-radius: 8px;
  flex-shrink: 0;
}

.task-panel-header img[hidden],
.task-panel-header .fallback-logo[hidden] {
  display: none !important;
}

.task-panel-header .fallback-logo {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  font-weight: 700;
  color: #fff;
}

.task-panel-header h3 {
  font-size: 1rem;
}

.task-panel-hint {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0.75rem;
}

.task-list {
  list-style: none;
  overflow-y: auto;
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding-right: 0.25rem;
}

.task-item {
  appearance: none;
  font: inherit;
  width: 100%;
  text-align: left;
  padding: 0.75rem 0.9rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  font-size: 0.85rem;
  line-height: 1.45;
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
}

.task-item:hover {
  border-color: rgba(91, 141, 239, 0.5);
}

.task-item.active {
  border-color: var(--accent);
  background: rgba(91, 141, 239, 0.12);
}

/* Live demo */
.demo-panel {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: calc(var(--radius) + 4px);
  padding: 2rem;
  box-shadow: var(--shadow);
}

.demo-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.demo-app-info {
  display: flex;
  align-items: center;
  gap: 1rem;
}

.demo-app-info .logo-slot {
  width: 40px;
  height: 40px;
  flex-shrink: 0;
  position: relative;
}

.demo-app-info .logo-slot img,
.demo-app-info .logo-slot .fallback-logo {
  width: 40px;
  height: 40px;
  border-radius: 10px;
}

.demo-app-info .logo-slot img[hidden],
.demo-app-info .logo-slot .fallback-logo[hidden] {
  display: none !important;
}

.demo-app-info .logo-slot .fallback-logo:not([hidden]) {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  font-weight: 700;
  color: #fff;
}

.demo-app-info h3 {
  font-size: 1rem;
}

.demo-app-info p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.demo-controls {
  display: flex;
  gap: 0.75rem;
}

.btn {
  padding: 0.55rem 1.1rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--bg-elevated);
  color: var(--text);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s, border-color 0.2s;
}

.btn:hover {
  border-color: rgba(91, 141, 239, 0.5);
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  border-color: transparent;
  color: #fff;
}

.btn-primary:hover {
  filter: brightness(1.08);
}

.instruction-box {
  min-height: 3.5rem;
  padding: 1rem 1.25rem;
  background: var(--bg-elevated);
  border-radius: 12px;
  border-left: 3px solid var(--accent);
  margin-bottom: 1.5rem;
  font-family: var(--mono);
  font-size: 0.95rem;
}

.instruction-box .cursor-blink {
  display: inline-block;
  width: 2px;
  height: 1.1em;
  background: var(--accent);
  margin-left: 2px;
  vertical-align: text-bottom;
  animation: blink 0.8s step-end infinite;
}

@keyframes blink {
  50% {
    opacity: 0;
  }
}

.action-label {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: var(--success);
  opacity: 0;
  transition: opacity 0.3s;
}

.action-label.visible {
  opacity: 1;
}

/* Trajectory strip */
.trajectory-viewport {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 1rem 0 1.5rem;
  scrollbar-width: thin;
  scrollbar-color: var(--accent) var(--bg-elevated);
}

.trajectory-strip {
  display: flex;
  align-items: flex-start;
  gap: 1.25rem;
  min-height: 420px;
  padding: 0.5rem;
}

.frame-card {
  flex: 0 0 auto;
  opacity: 0;
  transform: translateX(30px) scale(0.96);
  transition: opacity 0.5s ease, transform 0.5s ease;
}

.frame-card.visible {
  opacity: 1;
  transform: translateX(0) scale(1);
}

.frame-card.active {
  outline: 2px solid var(--accent);
  outline-offset: 4px;
  border-radius: 20px;
}

.phone-frame {
  position: relative;
  width: 200px;
  background: #111;
  border-radius: 24px;
  padding: 8px;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5);
}

.phone-screen {
  position: relative;
  border-radius: 18px;
  overflow: hidden;
  background: #000;
}

.phone-screen img {
  display: block;
  width: 100%;
  height: auto;
  vertical-align: top;
}

.frame-step {
  text-align: center;
  margin-top: 0.5rem;
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Tap cursor overlay */
.tap-cursor {
  position: absolute;
  width: 28px;
  height: 28px;
  pointer-events: none;
  z-index: 10;
  opacity: 0;
  transform: translate(-50%, -50%) scale(0.5);
  transition: opacity 0.15s, transform 0.15s;
}

.tap-cursor.show {
  opacity: 1;
  transform: translate(-50%, -50%) scale(1);
}

.tap-cursor .ring {
  position: absolute;
  inset: 0;
  border: 2px solid #fff;
  border-radius: 50%;
  box-shadow: 0 0 0 2px rgba(91, 141, 239, 0.8);
}

.tap-cursor .ring::after {
  content: "";
  position: absolute;
  inset: -8px;
  border: 2px solid rgba(91, 141, 239, 0.5);
  border-radius: 50%;
  animation: ripple 0.6s ease-out forwards;
}

@keyframes ripple {
  to {
    inset: -20px;
    opacity: 0;
  }
}

.tap-cursor svg {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-20%, -10%);
  filter: drop-shadow(0 2px 4px rgba(0, 0, 0, 0.6));
}

/* Scroll overlay */
.scroll-indicator {
  position: absolute;
  left: 50%;
  bottom: 12%;
  transform: translateX(-50%);
  opacity: 0;
  pointer-events: none;
  z-index: 10;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  color: #fff;
  font-size: 0.7rem;
  font-weight: 600;
  text-shadow: 0 1px 4px rgba(0, 0, 0, 0.8);
}

.scroll-indicator.show {
  opacity: 1;
  animation: scroll-bounce 1s ease-in-out;
}

.scroll-indicator.down svg {
  animation: scroll-arrow 0.8s ease-in-out infinite;
}

.scroll-indicator.up svg {
  animation: scroll-arrow-up 0.8s ease-in-out infinite;
}

@keyframes scroll-bounce {
  0%,
  100% {
    transform: translateX(-50%) translateY(0);
  }
  50% {
    transform: translateX(-50%) translateY(8px);
  }
}

@keyframes scroll-arrow {
  0%,
  100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(6px);
  }
}

@keyframes scroll-arrow-up {
  0%,
  100% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(-6px);
  }
}

.arrow-connector {
  flex: 0 0 40px;
  align-self: center;
  opacity: 0;
  transition: opacity 0.4s;
  color: var(--text-muted);
}

.arrow-connector.visible {
  opacity: 1;
}

/* Charts */
.charts-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2rem;
}

@media (max-width: 900px) {
  .charts-row {
    grid-template-columns: 1fr;
  }
}

.chart-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

.chart-card h3 {
  font-size: 1rem;
  margin-bottom: 1rem;
}

.chart-wrap {
  position: relative;
  height: 360px;
}

.chart-toggle {
  display: flex;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.chart-toggle .btn.active {
  border-color: var(--accent);
  color: var(--accent);
}

/* Footer */
footer {
  padding: 2rem 0;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
}

@media (max-width: 640px) {
  .nav-links {
    display: none;
  }

  .phone-frame {
    width: 160px;
  }
}