/* assets/css/main.css — Arsyn Design System */
@import url('https://fonts.googleapis.com/css2?family=Syne:wght@400;600;700;800&family=Space+Mono:wght@400;700&family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;1,9..40,300&display=swap');

/* ─── CSS Variables ─────────────────────────────────────── */
:root {
  --bg-0: #050508;
  --bg-1: #0a0b10;
  --bg-2: #0f1018;
  --bg-3: #151721;
  --bg-4: #1c1f2e;
  --surface: #1a1d28;
  --surface-2: #222535;
  --border: rgba(255,255,255,0.07);
  --border-bright: rgba(255,255,255,0.15);

  --accent: #FF4D1C;
  --accent-2: #00D4FF;
  --accent-3: #7CFC00;
  --accent-dim: rgba(255,77,28,0.15);
  --accent-2-dim: rgba(0,212,255,0.12);

  --text: #E8EAF0;
  --text-muted: #6B7280;
  --text-dim: #9CA3AF;

  --font-display: 'Syne', sans-serif;
  --font-mono: 'Space Mono', monospace;
  --font-body: 'DM Sans', sans-serif;

  --radius: 4px;
  --radius-lg: 12px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-slow: 0.6s cubic-bezier(0.4, 0, 0.2, 1);

  --glow-accent: 0 0 40px rgba(255,77,28,0.3);
  --glow-accent2: 0 0 40px rgba(0,212,255,0.3);
}

/* ─── Reset ─────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  background: var(--bg-0);
  color: var(--text);
  font-family: var(--font-body);
  font-weight: 300;
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
button { cursor: pointer; border: none; background: none; font: inherit; color: inherit; }
ul { list-style: none; }

/* ─── Noise overlay ─────────────────────────────────────── */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.03'/%3E%3C/svg%3E");
  background-size: 200px;
  pointer-events: none;
  z-index: 9999;
  opacity: 0.4;
}

/* ─── Scrollbar ─────────────────────────────────────────── */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: var(--bg-1); }
::-webkit-scrollbar-thumb { background: var(--accent); border-radius: 2px; }

/* ─── Typography ─────────────────────────────────────────── */
.display-xl {
  font-family: var(--font-display);
  font-size: clamp(3.5rem, 9vw, 8rem);
  font-weight: 800;
  line-height: 0.95;
  letter-spacing: -0.03em;
}
.display-lg {
  font-family: var(--font-display);
  font-size: clamp(2.5rem, 5vw, 4.5rem);
  font-weight: 700;
  line-height: 1;
  letter-spacing: -0.02em;
}
.display-md {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 3vw, 2.8rem);
  font-weight: 700;
  line-height: 1.1;
}
.label-tag {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
}
.accent { color: var(--accent); }
.accent-2 { color: var(--accent-2); }

/* ─── Layout ─────────────────────────────────────────────── */
.container {
  width: min(100%, 1280px);
  margin: 0 auto;
  padding: 0 clamp(1rem, 4vw, 3rem);
}
.section { padding: clamp(5rem, 10vw, 9rem) 0; }

/* ─── Buttons ─────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.9rem 2rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.9rem;
  letter-spacing: 0.05em;
  border-radius: var(--radius);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}
.btn::before {
  content: '';
  position: absolute;
  inset: 0;
  background: rgba(255,255,255,0.08);
  transform: translateX(-100%);
  transition: transform 0.4s cubic-bezier(0.4,0,0.2,1);
}
.btn:hover::before { transform: translateX(0); }

.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover {
  background: #ff3000;
  transform: translateY(-2px);
  box-shadow: var(--glow-accent);
}
.btn-outline {
  border: 1px solid var(--border-bright);
  color: var(--text);
  background: transparent;
}
.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}
.btn-ghost {
  color: var(--text-dim);
  padding: 0.5rem 0;
  font-size: 0.85rem;
}
.btn-ghost:hover { color: var(--accent); }
.btn-ghost .arrow { transition: transform 0.3s; }
.btn-ghost:hover .arrow { transform: translateX(4px); }

/* ─── Navigation ─────────────────────────────────────────── */
.nav {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 1000;
  transition: var(--transition);
  padding: 1.5rem 0;
}
.nav.scrolled {
  background: rgba(5, 5, 8, 0.92);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  padding: 1rem 0;
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-logo {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 1.4rem;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.nav-logo-dot {
  width: 7px; height: 7px;
  background: var(--accent);
  border-radius: 50%;
  animation: pulse-dot 2s ease-in-out infinite;
}
@keyframes pulse-dot {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.7); }
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}
.nav-link {
  font-family: var(--font-display);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  color: var(--text-dim);
  transition: var(--transition);
  position: relative;
}
.nav-link::after {
  content: '';
  position: absolute;
  bottom: -3px; left: 0; right: 0;
  height: 1px;
  background: var(--accent);
  transform: scaleX(0);
  transition: transform 0.3s;
}
.nav-link:hover, .nav-link.active { color: var(--text); }
.nav-link:hover::after, .nav-link.active::after { transform: scaleX(1); }
.nav-right {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

/* Lang switcher */
.lang-switcher {
  display: flex;
  gap: 4px;
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 3px;
}
.lang-btn {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  padding: 4px 8px;
  border-radius: 2px;
  color: var(--text-muted);
  transition: var(--transition);
}
.lang-btn:hover { color: var(--text); }
.lang-btn.active {
  background: var(--accent);
  color: #fff;
}

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 24px;
  padding: 2px;
}
.hamburger span {
  display: block;
  height: 1.5px;
  background: var(--text);
  transition: var(--transition);
  transform-origin: center;
}
.hamburger.open span:nth-child(1) { transform: translateY(6.5px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
.hamburger.open span:nth-child(3) { transform: translateY(-6.5px) rotate(-45deg); }

/* Mobile nav */
.mobile-nav {
  position: fixed;
  inset: 0;
  background: var(--bg-0);
  z-index: 999;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s;
}
.mobile-nav.open {
  opacity: 1;
  pointer-events: all;
}
.mobile-nav-link {
  font-family: var(--font-display);
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--text-dim);
  transition: var(--transition);
}
.mobile-nav-link:hover { color: var(--accent); }

/* ─── Hero Section ───────────────────────────────────────── */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
  padding-top: 5rem;
}
.hero-bg {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 80% 60% at 60% 50%, rgba(255,77,28,0.06) 0%, transparent 60%),
    radial-gradient(ellipse 50% 40% at 20% 80%, rgba(0,212,255,0.04) 0%, transparent 50%),
    var(--bg-0);
}
.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(var(--border) 1px, transparent 1px),
    linear-gradient(90deg, var(--border) 1px, transparent 1px);
  background-size: 60px 60px;
  mask-image: radial-gradient(ellipse 80% 80% at 50% 50%, black 0%, transparent 70%);
  animation: grid-drift 20s linear infinite;
}
@keyframes grid-drift {
  from { transform: translateY(0); }
  to { transform: translateY(60px); }
}
.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}
.hero-label {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  margin-bottom: 1.5rem;
  opacity: 0;
  animation: fade-up 0.8s 0.2s forwards;
}
.hero-label-line {
  width: 40px;
  height: 1px;
  background: var(--accent);
}
.hero-title {
  font-family: var(--font-display);
  font-size: clamp(4rem, 10vw, 9rem);
  font-weight: 800;
  line-height: 0.92;
  letter-spacing: -0.04em;
  margin-bottom: 1.5rem;
  opacity: 0;
  animation: fade-up 0.8s 0.4s forwards;
}
.hero-sub {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-muted);
  letter-spacing: 0.12em;
  margin-bottom: 3rem;
  opacity: 0;
  animation: fade-up 0.8s 0.6s forwards;
}
.hero-cta {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
  opacity: 0;
  animation: fade-up 0.8s 0.8s forwards;
}
.hero-scroll {
  position: absolute;
  bottom: 2.5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  opacity: 0;
  animation: fade-up 0.8s 1.2s forwards;
}
.scroll-indicator {
  width: 1px;
  height: 50px;
  background: linear-gradient(to bottom, transparent, var(--accent));
  animation: scroll-line 2s ease-in-out infinite;
}
@keyframes scroll-line {
  0% { transform: scaleY(0); transform-origin: top; opacity: 1; }
  50% { transform: scaleY(1); transform-origin: top; opacity: 1; }
  51% { transform: scaleY(1); transform-origin: bottom; }
  100% { transform: scaleY(0); transform-origin: bottom; opacity: 0; }
}

/* ─── Stats Bar ──────────────────────────────────────────── */
.stats-bar {
  background: var(--surface);
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  padding: 2.5rem 0;
}
.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--border);
}
.stat-item {
  background: var(--surface);
  padding: 1.5rem 2rem;
  text-align: center;
}
.stat-number {
  font-family: var(--font-display);
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  color: var(--accent);
  line-height: 1;
  margin-bottom: 0.3rem;
  display: block;
}
.stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  letter-spacing: 0.05em;
}

/* ─── Section Headers ────────────────────────────────────── */
.section-header {
  margin-bottom: clamp(3rem, 6vw, 5rem);
}
.section-header-inner {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}
.section-title-block {}
.section-sub {
  color: var(--text-muted);
  max-width: 400px;
  font-size: 0.95rem;
}

/* ─── Project Cards ──────────────────────────────────────── */
.projects-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(380px, 1fr));
  gap: 1px;
  background: var(--border);
}
.project-card {
  background: var(--bg-1);
  padding: 2.5rem;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
  cursor: pointer;
}
.project-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  transform: scaleX(0);
  transition: transform 0.5s;
}
.project-card:hover { background: var(--bg-2); }
.project-card:hover::before { transform: scaleX(1); }
.project-card-accent {
  width: 40px;
  height: 3px;
  border-radius: 2px;
  margin-bottom: 1.5rem;
  transition: width 0.3s;
}
.project-card:hover .project-card-accent { width: 60px; }
.project-card-meta {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1rem;
}
.project-card-cat {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.project-card-year {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  color: var(--text-muted);
  margin-left: auto;
}
.project-card h3 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.3rem;
  margin-bottom: 0.5rem;
  line-height: 1.2;
}
.project-card p {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 1.5rem;
}
.project-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem;
  margin-bottom: 1.5rem;
}
.tag {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.08em;
  padding: 3px 8px;
  border: 1px solid var(--border);
  border-radius: 2px;
  color: var(--text-muted);
}

/* ─── R&D Cards ──────────────────────────────────────────── */
.rd-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(500px, 1fr));
  gap: 2px;
  background: var(--border);
}
.rd-card {
  background: var(--bg-1);
  padding: 3rem;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}
.rd-card:hover { background: var(--bg-2); }
.rd-card-glow {
  position: absolute;
  top: -50px; right: -50px;
  width: 200px; height: 200px;
  border-radius: 50%;
  filter: blur(60px);
  opacity: 0.15;
  transition: opacity 0.5s;
}
.rd-card:hover .rd-card-glow { opacity: 0.25; }
.rd-status {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-bottom: 1rem;
}
.rd-status-dot {
  width: 6px; height: 6px;
  background: var(--accent-3);
  border-radius: 50%;
  animation: blink 1.5s ease-in-out infinite;
}
@keyframes blink {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.3; }
}
.rd-card h3 {
  font-family: var(--font-display);
  font-size: 1.8rem;
  font-weight: 700;
  line-height: 1.1;
  margin-bottom: 0.3rem;
}
.rd-card-subtitle {
  font-family: var(--font-mono);
  font-size: 0.7rem;
  color: var(--text-muted);
  letter-spacing: 0.1em;
  margin-bottom: 1.5rem;
}

/* Dev log */
.dev-log {
  margin-top: 2rem;
  border-left: 1px solid var(--border);
  padding-left: 1.5rem;
}
.log-entry {
  position: relative;
  margin-bottom: 1.5rem;
}
.log-entry::before {
  content: '';
  position: absolute;
  left: -1.6rem;
  top: 0.4rem;
  width: 8px; height: 8px;
  border: 1px solid var(--accent);
  border-radius: 50%;
  background: var(--bg-1);
}
.log-date {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  color: var(--accent);
  letter-spacing: 0.1em;
  margin-bottom: 0.2rem;
}
.log-title {
  font-family: var(--font-display);
  font-weight: 600;
  font-size: 0.85rem;
  margin-bottom: 0.3rem;
}
.log-body {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* Resources */
.resources-list {
  margin-top: 1.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.resource-item {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.7rem 1rem;
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: var(--transition);
  font-size: 0.82rem;
}
.resource-item:hover {
  border-color: var(--accent-2);
  background: var(--bg-4);
}
.resource-type {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.1em;
  padding: 2px 6px;
  background: var(--accent-2-dim);
  color: var(--accent-2);
  border-radius: 2px;
  white-space: nowrap;
}
.resource-dl-icon {
  margin-left: auto;
  color: var(--text-muted);
  font-size: 0.8rem;
}

/* ─── Services Grid ──────────────────────────────────────── */
.services-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 1px;
  background: var(--border);
}
.service-card {
  background: var(--bg-1);
  padding: 2.5rem;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}
.service-card::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0; right: 0;
  height: 2px;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s;
}
.service-card:hover { background: var(--bg-2); }
.service-card:hover::after { transform: scaleX(1); }
.service-icon {
  font-size: 2rem;
  margin-bottom: 1.2rem;
  display: block;
}
.service-card h3 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.1rem;
  margin-bottom: 0.6rem;
}
.service-card p {
  font-size: 0.84rem;
  color: var(--text-muted);
  line-height: 1.7;
}

/* ─── Learn Section ──────────────────────────────────────── */
.learn-categories {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 1px;
  background: var(--border);
}
.learn-cat-card {
  background: var(--bg-1);
  padding: 2rem;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}
.learn-cat-card:hover { background: var(--bg-2); }
.learn-cat-icon {
  font-size: 1.8rem;
  margin-bottom: 1rem;
  display: block;
  transition: transform 0.3s;
}
.learn-cat-card:hover .learn-cat-icon { transform: scale(1.2) rotate(5deg); }
.learn-cat-card h3 {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 0.8rem;
}
.learn-cat-children {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.learn-cat-child {
  font-size: 0.75rem;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}
.learn-cat-child::before {
  content: '—';
  color: var(--border-bright);
  font-size: 0.6rem;
}
.learn-cat-bar {
  position: absolute;
  bottom: 0; left: 0;
  height: 2px;
  width: 0;
  transition: width 0.4s;
}
.learn-cat-card:hover .learn-cat-bar { width: 100%; }

/* ─── Contact Section ────────────────────────────────────── */
.contact-section { background: var(--bg-1); }
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 6rem;
  align-items: start;
}
.contact-form {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}
.form-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.form-input, .form-textarea {
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.9rem 1.1rem;
  color: var(--text);
  font-family: var(--font-body);
  font-size: 0.9rem;
  transition: var(--transition);
  outline: none;
}
.form-input:focus, .form-textarea:focus {
  border-color: var(--accent);
  background: var(--bg-4);
  box-shadow: 0 0 0 3px rgba(255,77,28,0.1);
}
.form-textarea { resize: vertical; min-height: 140px; }
.contact-info { padding-top: 1rem; }
.contact-info-item {
  display: flex;
  align-items: flex-start;
  gap: 1rem;
  margin-bottom: 1.5rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border);
}
.contact-info-icon {
  width: 40px; height: 40px;
  background: var(--bg-3);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1rem;
  flex-shrink: 0;
}
.contact-info-text small {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 0.2rem;
}
.contact-info-text span { font-size: 0.9rem; }

/* ─── Footer ─────────────────────────────────────────────── */
.footer {
  background: var(--bg-0);
  border-top: 1px solid var(--border);
  padding: 4rem 0 2rem;
}
.footer-top {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  gap: 3rem;
  margin-bottom: 3rem;
  padding-bottom: 3rem;
  border-bottom: 1px solid var(--border);
}
.footer-logo {
  font-family: var(--font-display);
  font-size: 1.6rem;
  font-weight: 800;
  margin-bottom: 0.8rem;
}
.footer-tagline {
  font-size: 0.84rem;
  color: var(--text-muted);
  max-width: 260px;
  line-height: 1.6;
}
.footer-col h4 {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--text-muted);
  margin-bottom: 1rem;
}
.footer-links-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}
.footer-links-list a {
  font-size: 0.85rem;
  color: var(--text-dim);
  transition: var(--transition);
}
.footer-links-list a:hover { color: var(--accent); }
.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  flex-wrap: wrap;
}
.footer-legal {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* ─── Animations ─────────────────────────────────────────── */
@keyframes fade-up {
  from { opacity: 0; transform: translateY(30px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes fade-in {
  from { opacity: 0; }
  to { opacity: 1; }
}
.reveal {
  opacity: 0;
  transform: translateY(40px);
  transition: opacity 0.7s cubic-bezier(0.4,0,0.2,1),
              transform 0.7s cubic-bezier(0.4,0,0.2,1);
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}
.reveal-delay-1 { transition-delay: 0.1s; }
.reveal-delay-2 { transition-delay: 0.2s; }
.reveal-delay-3 { transition-delay: 0.3s; }
.reveal-delay-4 { transition-delay: 0.4s; }

/* ─── Cursor ─────────────────────────────────────────────── */
.cursor {
  position: fixed;
  width: 8px; height: 8px;
  background: var(--accent);
  border-radius: 50%;
  pointer-events: none;
  z-index: 9998;
  transform: translate(-50%, -50%);
  transition: transform 0.1s, width 0.3s, height 0.3s, opacity 0.3s;
  mix-blend-mode: screen;
}
.cursor-ring {
  position: fixed;
  width: 32px; height: 32px;
  border: 1px solid rgba(255,77,28,0.4);
  border-radius: 50%;
  pointer-events: none;
  z-index: 9997;
  transform: translate(-50%, -50%);
  transition: transform 0.15s cubic-bezier(0.4,0,0.2,1),
              width 0.3s, height 0.3s, border-color 0.3s;
}
.cursor.hover { width: 14px; height: 14px; }
.cursor-ring.hover { width: 50px; height: 50px; border-color: rgba(255,77,28,0.7); }

/* ─── Page header (inner pages) ─────────────────────────── */
.page-hero {
  padding: 10rem 0 5rem;
  position: relative;
  overflow: hidden;
}
.page-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(ellipse 70% 70% at 30% 50%, rgba(255,77,28,0.07) 0%, transparent 60%);
}
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1.5rem;
}
.breadcrumb a, .breadcrumb span {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.1em;
  color: var(--text-muted);
  transition: color 0.2s;
}
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb-sep { color: var(--border-bright); }

/* ─── Project Detail ─────────────────────────────────────── */
.project-detail-grid {
  display: grid;
  grid-template-columns: 2fr 1fr;
  gap: 4rem;
  align-items: start;
}
.project-section {
  margin-bottom: 3rem;
}
.project-section-label {
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.8rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}
.project-section-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}
.project-results-list {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}
.result-item {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  font-size: 0.9rem;
}
.result-item::before {
  content: '✓';
  width: 22px; height: 22px;
  background: rgba(124,252,0,0.1);
  color: var(--accent-3);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.7rem;
  flex-shrink: 0;
}
.project-sidebar-card {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  position: sticky;
  top: 6rem;
}
.sidebar-meta-item {
  margin-bottom: 1.2rem;
  padding-bottom: 1.2rem;
  border-bottom: 1px solid var(--border);
}
.sidebar-meta-item:last-child { border-bottom: none; margin-bottom: 0; padding-bottom: 0; }
.sidebar-meta-item small {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
  display: block;
  margin-bottom: 0.3rem;
}
.sidebar-meta-item span { font-size: 0.9rem; }

/* ─── Tutorial Page ──────────────────────────────────────── */
.tutorial-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 3rem;
  align-items: start;
}
.tutorial-sidebar {
  position: sticky;
  top: 6rem;
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.tutorial-sidebar-header {
  padding: 1.2rem 1.5rem;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.tutorial-nav-item {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.8rem 1.5rem;
  font-size: 0.85rem;
  color: var(--text-dim);
  border-left: 2px solid transparent;
  transition: var(--transition);
  cursor: pointer;
}
.tutorial-nav-item:hover { color: var(--text); background: var(--bg-3); }
.tutorial-nav-item.active {
  color: var(--accent);
  border-left-color: var(--accent);
  background: var(--accent-dim);
}
.tutorial-content {}
.tutorial-section-block {
  margin-bottom: 3rem;
  padding-bottom: 3rem;
  border-bottom: 1px solid var(--border);
}
.tutorial-section-block:last-child { border-bottom: none; }
.tutorial-section-block h2 {
  font-family: var(--font-display);
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 1rem;
}
.tutorial-section-block p {
  color: var(--text-dim);
  line-height: 1.8;
  margin-bottom: 1.5rem;
}
/* Code block */
.code-block {
  background: var(--bg-0);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 1.5rem;
}
.code-block-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 1rem;
  background: var(--bg-3);
  border-bottom: 1px solid var(--border);
}
.code-block-lang {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.1em;
  color: var(--accent);
}
.copy-btn {
  font-family: var(--font-mono);
  font-size: 0.6rem;
  color: var(--text-muted);
  padding: 2px 6px;
  border: 1px solid var(--border);
  border-radius: 2px;
  transition: var(--transition);
}
.copy-btn:hover { color: var(--text); border-color: var(--text-muted); }
.code-block pre {
  padding: 1.2rem 1.5rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  line-height: 1.8;
  color: #a8b4c8;
}
.code-block pre .kw { color: #00D4FF; }
.code-block pre .str { color: #7CFC00; }
.code-block pre .cmt { color: #4a5568; }
.code-block pre .num { color: #FF4D1C; }
/* Exercise */
.exercise-block {
  background: rgba(0,212,255,0.04);
  border: 1px solid rgba(0,212,255,0.15);
  border-radius: var(--radius);
  padding: 1.5rem;
}
.exercise-label {
  font-family: var(--font-mono);
  font-size: 0.62rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 0.8rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.exercise-question {
  font-size: 0.9rem;
  margin-bottom: 1rem;
}
.exercise-input {
  width: 100%;
  background: var(--bg-0);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.8rem 1rem;
  font-family: var(--font-mono);
  font-size: 0.8rem;
  color: var(--text);
  transition: var(--transition);
  outline: none;
  min-height: 80px;
  resize: vertical;
}
.exercise-input:focus {
  border-color: var(--accent-2);
  box-shadow: 0 0 0 3px rgba(0,212,255,0.1);
}
.exercise-actions {
  display: flex;
  gap: 0.8rem;
  margin-top: 0.8rem;
}
.exercise-hint {
  margin-top: 0.8rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  padding: 0.6rem 1rem;
  background: var(--bg-3);
  border-radius: var(--radius);
  display: none;
}
.exercise-hint.show { display: block; }
.exercise-result {
  margin-top: 0.8rem;
  font-size: 0.82rem;
  padding: 0.6rem 1rem;
  border-radius: var(--radius);
  display: none;
}
.exercise-result.correct {
  display: block;
  background: rgba(124,252,0,0.08);
  color: var(--accent-3);
  border: 1px solid rgba(124,252,0,0.2);
}
.exercise-result.wrong {
  display: block;
  background: rgba(255,77,28,0.08);
  color: var(--accent);
  border: 1px solid rgba(255,77,28,0.2);
}

/* YouTube embed */
.yt-wrapper {
  position: relative;
  padding-bottom: 56.25%;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  margin-bottom: 2rem;
}
.yt-wrapper iframe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

/* ─── Learn Tree ─────────────────────────────────────────── */
.learn-tree {
  background: var(--bg-2);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
}
.learn-tree-header {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  font-family: var(--font-mono);
  font-size: 0.65rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.tree-item {
  border-bottom: 1px solid var(--border);
}
.tree-item:last-child { border-bottom: none; }
.tree-parent {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.9rem 1.5rem;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.85rem;
  font-family: var(--font-display);
  font-weight: 600;
}
.tree-parent:hover { background: var(--bg-3); }
.tree-parent.open { background: var(--bg-3); }
.tree-chevron {
  margin-left: auto;
  font-size: 0.7rem;
  color: var(--text-muted);
  transition: transform 0.3s;
}
.tree-parent.open .tree-chevron { transform: rotate(90deg); }
.tree-children {
  display: none;
  border-top: 1px solid var(--border);
}
.tree-children.open { display: block; }
.tree-child {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.65rem 1.5rem 0.65rem 3rem;
  font-size: 0.8rem;
  color: var(--text-muted);
  transition: var(--transition);
  cursor: pointer;
}
.tree-child:hover { background: var(--bg-4); color: var(--text); }
.tree-child::before { content: '›'; color: var(--accent); }

/* ─── Animated counter ───────────────────────────────────── */
.counter { display: inline-block; }

/* ─── Responsive ─────────────────────────────────────────── */
@media (max-width: 1100px) {
  .contact-grid { grid-template-columns: 1fr; gap: 3rem; }
  .rd-grid { grid-template-columns: 1fr; }
  .project-detail-grid { grid-template-columns: 1fr; }
  .tutorial-layout { grid-template-columns: 1fr; }
  .tutorial-sidebar { position: static; }
}
@media (max-width: 900px) {
  .footer-top { grid-template-columns: 1fr 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .projects-grid { grid-template-columns: 1fr; }
}
@media (max-width: 700px) {
  .nav-links, .nav-right .btn { display: none; }
  .hamburger { display: flex; }
  .footer-top { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); }
  .hero-title { font-size: clamp(3rem, 15vw, 5rem); }
  .services-grid { grid-template-columns: 1fr; }
  .learn-categories { grid-template-columns: repeat(2, 1fr); }
  .section-header-inner { flex-direction: column; align-items: flex-start; }
  .cursor, .cursor-ring { display: none; }
}
@media (max-width: 480px) {
  .stats-grid { grid-template-columns: 1fr 1fr; }
  .learn-categories { grid-template-columns: 1fr; }
  .hero-cta { flex-direction: column; }
  .hero-cta .btn { width: 100%; justify-content: center; }
}