/* ElBot Landing — Low-saturation blue, concept design */

:root {
  --bg: #0a0f14;
  --bg-soft: #0f1620;
  --bg-card: #121b27;
  --line: #1a2638;
  --line-soft: #16203200;
  --text: #c8d4e3;
  --text-dim: #6b7d94;
  --text-faint: #4a5a72;
  --accent: #4a90d9;
  --accent-soft: #2a5a8a;
  --accent-glow: #4a90d920;
  --radius: 12px;
  --radius-sm: 8px;
  --transition: 0.4s cubic-bezier(0.2, 0.8, 0.2, 1);
}

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

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

/* === Nav === */
#nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  padding: 1.2rem 2rem;
  transition: var(--transition);
}
#nav.scrolled {
  background: var(--bg-elevated);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.logo {
  font-weight: 600;
  font-size: 1.1rem;
  letter-spacing: -0.02em;
  color: var(--text);
}
.nav-links {
  display: flex;
  gap: 2rem;
}
.nav-links a {
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--text-dim);
  transition: color var(--transition);
}
.nav-links a:hover { color: var(--text); }
.lang-toggle {
  color: var(--text-faint);
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 400;
  transition: color var(--transition);
  user-select: none;
  border-left: 1px solid var(--line);
  padding-left: 1.5rem;
}
.lang-toggle:hover {
  color: var(--text);
}

/* === Hero === */
#hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 60% 50% at 50% 40%, var(--accent-glow), transparent 70%),
    radial-gradient(ellipse 40% 30% at 80% 80%, #1a3a5a18, transparent 60%);
}
.hero-bg::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 80px 80px;
  opacity: 0.15;
  mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black, transparent 80%);
  -webkit-mask-image: radial-gradient(ellipse 70% 60% at 50% 50%, black, transparent 80%);
}
.hero-content {
  position: relative;
  text-align: center;
  z-index: 1;
  padding: 0 2rem;
}
.hero-label {
  font-size: 0.75rem;
  font-weight: 400;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 2rem;
}
.hero-content h1 {
  font-size: clamp(3rem, 8vw, 6rem);
  font-weight: 200;
  line-height: 1.05;
  letter-spacing: -0.04em;
  color: var(--text);
}
.hero-accent {
  font-weight: 500;
  background: linear-gradient(135deg, var(--accent), #7ab5e8);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero-sub {
  margin-top: 2rem;
  font-size: 1rem;
  font-weight: 300;
  color: var(--text-dim);
  letter-spacing: 0.02em;
}
.hero-cta {
  margin-top: 3rem;
  display: flex;
  gap: 1rem;
  justify-content: center;
}
.btn-primary {
  padding: 0.8rem 2rem;
  background: var(--accent);
  color: #fff;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 500;
  transition: var(--transition);
}
.btn-primary:hover {
  background: #5a9ee8;
  transform: translateY(-1px);
  box-shadow: 0 8px 24px var(--accent-glow);
}
.btn-ghost {
  padding: 0.8rem 2rem;
  border: 1px solid var(--line);
  color: var(--text-dim);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 500;
  transition: var(--transition);
}
.btn-ghost:hover {
  border-color: var(--text-faint);
  color: var(--text);
}
.hero-scroll {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  font-size: 0.7rem;
  letter-spacing: 0.2em;
  color: var(--text-faint);
  animation: scrollPulse 2s ease-in-out infinite;
}
@keyframes scrollPulse {
  0%, 100% { opacity: 0.3; }
  50% { opacity: 0.8; }
}

/* === Stats === */
#stats {
  padding: 4rem 2rem;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.stats-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
}
.stat-card {
  text-align: center;
}
.stat-value {
  display: block;
  font-size: 2.5rem;
  font-weight: 200;
  color: var(--text);
  letter-spacing: -0.03em;
}
.stat-unit {
  font-size: 1rem;
  font-weight: 300;
  color: var(--accent);
  margin-left: 0.2rem;
}
.stat-label {
  display: block;
  margin-top: 0.5rem;
  font-size: 0.75rem;
  color: var(--text-faint);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

/* === Sections === */
#features, #architecture, #start {
  padding: 8rem 2rem;
}
.section-header {
  max-width: 1200px;
  margin: 0 auto 4rem;
  display: flex;
  align-items: baseline;
  gap: 1.5rem;
}
.section-num {
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--accent);
  letter-spacing: 0.1em;
}
.section-header h2 {
  font-size: 2rem;
  font-weight: 300;
  letter-spacing: -0.02em;
}

/* === Features === */
.features-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}
.feature-card {
  padding: 2.5rem;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: var(--transition);
}
.feature-card:hover {
  border-color: var(--accent-soft);
  transform: translateY(-2px);
}
.feature-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 1.5rem;
  color: var(--accent);
}
.feature-card h3 {
  font-size: 1.1rem;
  font-weight: 500;
  margin-bottom: 0.5rem;
  color: var(--text);
}
.feature-card p {
  font-size: 0.85rem;
  font-weight: 300;
  color: var(--text-dim);
}

/* === Architecture === */
.arch-container {
  max-width: 800px;
  margin: 0 auto;
}
.arch-diagram {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0;
}
.arch-layer {
  width: 100%;
  padding: 1.5rem 2rem;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  gap: 2rem;
  transition: var(--transition);
}
.arch-layer:hover {
  border-color: var(--accent-soft);
}
.arch-layer-core {
  border-color: var(--accent-soft);
  background: linear-gradient(135deg, var(--bg-card), #0d1520);
}
.arch-label {
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  min-width: 70px;
}
.arch-items {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
}
.arch-items span {
  padding: 0.3rem 0.9rem;
  font-size: 0.8rem;
  font-weight: 400;
  color: var(--text-dim);
  border: 1px solid var(--line);
  border-radius: 20px;
}
.arch-arrow {
  width: 1px;
  height: 2rem;
  background: linear-gradient(var(--accent-soft), transparent);
}

/* === Architecture Blocks === */
.arch-svg {
  max-width: 900px;
  margin: 0 auto;
}
.arch-row {
  display: flex;
  gap: 1.5rem;
  justify-content: center;
  flex-wrap: wrap;
}
.arch-row-core {
  position: relative;
  align-items: center;
  flex-wrap: nowrap;
  min-height: 12rem;
}
.arch-block {
  flex: 1;
  min-width: 180px;
  max-width: 280px;
  padding: 1.5rem;
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: var(--transition);
}
.arch-block:hover {
  border-color: var(--accent-soft);
}
.arch-block-core {
  border-color: var(--accent-soft);
  background: linear-gradient(135deg, var(--bg-card), #0d1520);
}
.arch-block-hook {
  position: absolute;
  left: calc(50% + 330px);
  flex: none;
  width: 220px;
  min-width: 0;
  border-style: dashed;
  border-color: rgba(125, 164, 194, 0.35);
  background: linear-gradient(135deg, rgba(125, 164, 194, 0.08), var(--bg-card));
}
.arch-block-hook::before {
  content: '';
  position: absolute;
  top: 50%;
  right: 100%;
  width: 2rem;
  border-top: 1px dashed rgba(125, 164, 194, 0.35);
}
.arch-block-wide {
  max-width: 600px;
}
.arch-block-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 0.3rem;
}
.arch-block-core .arch-block-label,
.arch-block-hook .arch-block-label {
  color: var(--accent);
}
.arch-block-sub {
  font-size: 0.7rem;
  color: var(--text-faint);
  margin-bottom: 0.8rem;
}
.arch-block-items {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.arch-block-items span {
  padding: 0.25rem 0.7rem;
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--text-dim);
  border: 1px solid var(--line);
  border-radius: 20px;
}
.arch-arrow-down {
  width: 1px;
  height: 2.5rem;
  margin: 0 auto;
  background: linear-gradient(var(--accent-soft), transparent);
}
@media (max-width: 1100px) {
  .arch-row-core {
    flex-wrap: wrap;
    min-height: 0;
  }
  .arch-block-hook {
    position: relative;
    left: auto;
    width: auto;
    max-width: 280px;
  }
  .arch-block-hook::before {
    display: none;
  }
}
@media (max-width: 600px) {
  .arch-row { flex-direction: column; align-items: center; }
  .arch-row-core { flex-wrap: nowrap; }
  .arch-block { width: 100%; max-width: none; }
}

/* === Quick Start === */
.start-container {
  max-width: 1000px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 3rem;
  align-items: start;
}
.code-block {
  background: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
}
.code-header {
  padding: 0.8rem 1.5rem;
  border-bottom: 1px solid var(--line);
  font-size: 0.75rem;
  color: var(--text-faint);
  letter-spacing: 0.1em;
}
.code-block pre {
  padding: 1.5rem;
  font-family: 'SF Mono', 'Monaco', 'Cascadia Code', monospace;
  font-size: 0.85rem;
  line-height: 1.8;
}
.c-comment { color: var(--text-faint); }
.c-key { color: var(--accent); font-weight: 500; }
.c-flag { color: var(--text); }
.start-links {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
  padding-top: 1rem;
}
.start-links a {
  width: fit-content;
  font-size: 0.9rem;
  font-weight: 400;
  color: var(--text-dim);
  padding: 0.6rem 0;
  border-bottom: 1px solid var(--line);
  transition: color var(--transition);
  display: inline-flex;
  align-items: center;
}
.start-links a::after {
  content: '→';
  margin-left: 0.5rem;
  opacity: 0;
  transform: translateX(-0.25rem);
  transition: opacity var(--transition), transform var(--transition);
}
.start-links a:hover {
  color: var(--text);
}
.start-links a:hover::after {
  opacity: 1;
  transform: translateX(0);
}

/* === Footer === */
footer {
  border-top: 1px solid var(--line);
  padding: 4rem 2rem 2rem;
}
.footer-inner {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
}
.footer-logo {
  font-size: 1.2rem;
  font-weight: 600;
  color: var(--text);
}
.footer-brand p {
  margin-top: 0.5rem;
  font-size: 0.85rem;
  font-weight: 300;
  color: var(--text-faint);
}
.footer-links {
  display: flex;
  gap: 2rem;
}
.footer-links a {
  font-size: 0.85rem;
  color: var(--text-dim);
  transition: var(--transition);
}
.footer-links a:hover { color: var(--text); }
.footer-bottom {
  max-width: 1200px;
  margin: 3rem auto 0;
  padding-top: 2rem;
  border-top: 1px solid var(--line);
}
.footer-bottom p {
  font-size: 0.75rem;
  color: var(--text-faint);
}

/* === Responsive === */
@media (max-width: 900px) {
  .features-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 3rem; }
  .start-container { grid-template-columns: 1fr; }
  .nav-links { display: none; }
}
@media (max-width: 600px) {
  .stats-grid { grid-template-columns: 1fr; }
  #features, #architecture, #start { padding: 5rem 1.5rem; }
  .arch-layer { flex-direction: column; align-items: flex-start; gap: 1rem; }
  .footer-inner { flex-direction: column; gap: 2rem; }
}