/* ==========================================================================
   YUEJIETRADE - Main Stylesheet
   Tech-Forward / Data Visualization Theme
   ========================================================================== */

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

:root {
  --bg-0: #03051a;
  --bg-1: #0a0e27;
  --bg-2: #11173d;
  --bg-3: #1a2851;
  --text-1: #e8f4ff;
  --text-2: #a8c0d8;
  --text-3: #6b7a99;
  --neon-cyan: #00f0ff;
  --neon-green: #00ff9d;
  --neon-purple: #7c4dff;
  --neon-pink: #ff4081;
  --neon-amber: #ffb74d;
  --grad-primary: linear-gradient(135deg, #00f0ff 0%, #7c4dff 50%, #00ff9d 100%);
  --grad-cyan: linear-gradient(135deg, #00f0ff, #00ff9d);
  --grad-purple: linear-gradient(135deg, #7c4dff, #ff4081);
  --grad-card: linear-gradient(145deg, rgba(26,40,81,0.6), rgba(10,14,39,0.8));
  --border-glow: rgba(0, 240, 255, 0.3);
  --border-soft: rgba(124, 77, 255, 0.2);
  --font-display: 'Orbitron', 'Rajdhani', 'Segoe UI', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Courier New', monospace;
  --font-body: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
  --shadow-glow: 0 0 30px rgba(0, 240, 255, 0.3);
  --shadow-purple: 0 0 30px rgba(124, 77, 255, 0.3);
}

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
  font-family: var(--font-body);
  background: var(--bg-0);
  color: var(--text-1);
  line-height: 1.6;
  overflow-x: hidden;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
}
h1 { font-size: clamp(2.4rem, 5.5vw, 4.5rem); }
h2 { font-size: clamp(1.8rem, 3.6vw, 2.8rem); }
h3 { font-size: clamp(1.3rem, 2.4vw, 1.7rem); }
h4 { font-size: 1.15rem; }
p  { color: var(--text-2); margin-bottom: 1rem; }

a { color: var(--neon-cyan); text-decoration: none; transition: all 0.3s ease; }
a:hover { color: var(--neon-green); }

.container { max-width: 1280px; margin: 0 auto; padding: 0 24px; }
.container-wide { max-width: 1440px; margin: 0 auto; padding: 0 24px; }

.text-gradient {
  background: var(--grad-primary);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: transparent;
}
.text-cyan { color: var(--neon-cyan); }
.text-green { color: var(--neon-green); }
.text-purple { color: var(--neon-purple); }
.text-mono { font-family: var(--font-mono); }

.highlight-line { position: relative; display: inline-block; }
.highlight-line::after {
  content: ''; position: absolute; left: 0; bottom: 4px;
  width: 100%; height: 8px;
  background: linear-gradient(90deg, rgba(0,240,255,0.4), rgba(124,77,255,0.4));
  z-index: -1;
}

section { position: relative; padding: 100px 0; z-index: 1; }
.section-header { text-align: center; margin-bottom: 64px; }
.section-header h2 { margin-bottom: 16px; }
.section-header p { max-width: 720px; margin: 0 auto; font-size: 1.1rem; }
.section-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 3px;
  color: var(--neon-cyan);
  text-transform: uppercase;
  margin-bottom: 12px;
  padding: 6px 14px;
  border: 1px solid var(--border-glow);
  border-radius: 100px;
  background: rgba(0, 240, 255, 0.05);
}
.section-tag::before { content: '// '; opacity: 0.5; }

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 28px; border-radius: 8px;
  font-family: var(--font-display); font-weight: 600;
  font-size: 0.95rem; letter-spacing: 0.5px;
  cursor: pointer; border: none; transition: all 0.3s ease;
  text-decoration: none; position: relative; overflow: hidden;
}
.btn-primary {
  background: var(--grad-primary);
  color: var(--bg-0);
  box-shadow: 0 4px 20px rgba(0, 240, 255, 0.4);
}
.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 8px 30px rgba(0, 240, 255, 0.6);
  color: var(--bg-0);
}
.btn-ghost {
  background: transparent;
  color: var(--neon-cyan);
  border: 1.5px solid var(--neon-cyan);
}
.btn-ghost:hover {
  background: rgba(0, 240, 255, 0.1);
  box-shadow: var(--shadow-glow);
  color: var(--neon-cyan);
}
.btn .icon { width: 18px; height: 18px; }

.card {
  background: var(--grad-card);
  border: 1px solid var(--border-soft);
  border-radius: 16px;
  padding: 32px;
  position: relative; overflow: hidden;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}
.card:hover {
  transform: translateY(-6px);
  border-color: var(--neon-cyan);
  box-shadow: 0 20px 60px rgba(0, 240, 255, 0.15);
}
.card::before {
  content: ''; position: absolute; top: 0; left: 0;
  width: 100%; height: 2px;
  background: var(--grad-primary);
  transform: scaleX(0); transform-origin: left;
  transition: transform 0.5s ease;
}
.card:hover::before { transform: scaleX(1); }

/* Navbar */
.nav {
  position: fixed; top: 0; left: 0; width: 100%; z-index: 1000;
  padding: 16px 0;
  background: rgba(3, 5, 26, 0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid rgba(0, 240, 255, 0.1);
  transition: all 0.3s ease;
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; }
.nav-logo { display: flex; align-items: center; }
.nav-logo img { height: 42px; }
.nav-links { display: flex; align-items: center; gap: 4px; list-style: none; }
.nav-links a {
  display: block; padding: 10px 18px;
  font-family: var(--font-display); font-size: 0.88rem;
  font-weight: 500; letter-spacing: 1px;
  color: var(--text-2); text-transform: uppercase;
  border-radius: 6px; transition: all 0.3s ease;
}
.nav-links a:hover, .nav-links a.active {
  color: var(--neon-cyan);
  background: rgba(0, 240, 255, 0.08);
}
.nav-cta {
  padding: 10px 20px;
  background: var(--grad-cyan);
  color: var(--bg-0) !important;
  border-radius: 6px;
  font-weight: 700 !important;
}
.nav-cta:hover { box-shadow: var(--shadow-glow); }
.nav-toggle { display: none; background: none; border: none; cursor: pointer; }
.nav-toggle .icon { width: 28px; height: 28px; color: var(--neon-cyan); }

/* Footer */
.footer {
  background: var(--bg-1);
  border-top: 1px solid var(--border-soft);
  padding: 80px 0 24px;
  position: relative; overflow: hidden;
  z-index: 2;
}
.footer::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0;
  height: 1px; background: var(--grad-primary);
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr 1.2fr;
  gap: 48px;
  margin: 0 auto 56px;
  max-width: 100%;
}
.footer-brand h4 { margin-bottom: 12px; font-size: 1.2rem; }
.footer-brand p { font-size: 0.92rem; }
.footer-col h5 {
  font-family: var(--font-mono);
  font-size: 0.78rem; letter-spacing: 2px;
  color: var(--neon-cyan);
  margin-bottom: 18px; text-transform: uppercase;
}
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: 10px; }
.footer-col a { color: var(--text-2); font-size: 0.92rem; }
.footer-col a:hover { color: var(--neon-cyan); padding-left: 4px; }
.footer-contact-item {
  display: flex; align-items: flex-start; gap: 10px;
  margin-bottom: 14px;
}
.footer-contact-item .icon {
  width: 18px; height: 18px; flex-shrink: 0;
  color: var(--neon-cyan); margin-top: 2px;
}
.footer-contact-item .text { font-size: 0.88rem; color: var(--text-2); }
.footer-social { display: flex; gap: 12px; margin-top: 16px; }
.footer-social a {
  width: 38px; height: 38px;
  display: flex; align-items: center; justify-content: center;
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  transition: all 0.3s ease;
}
.footer-social a:hover {
  border-color: var(--neon-cyan);
  background: rgba(0, 240, 255, 0.1);
}
.footer-social .icon { width: 18px; height: 18px; }
.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid rgba(124, 77, 255, 0.15);
  display: flex; justify-content: space-between; align-items: center;
  font-size: 0.85rem; color: var(--text-3);
  flex-wrap: wrap; gap: 16px;
}
.footer-bottom-links { display: flex; gap: 20px; flex-wrap: wrap; }
.footer-bottom-links a { color: var(--text-2); }

/* Background grid pattern (global) */
.bg-grid {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  pointer-events: none; z-index: -2;
  background-image:
    linear-gradient(rgba(0, 240, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 240, 255, 0.03) 1px, transparent 1px);
  background-size: 50px 50px;
}
.bg-glow-orb {
  position: fixed; pointer-events: none; z-index: -1;
  border-radius: 50%; filter: blur(80px); opacity: 0.4;
}
.bg-glow-orb.cyan { width: 500px; height: 500px; background: var(--neon-cyan); top: 10%; left: -10%; }
.bg-glow-orb.purple { width: 600px; height: 600px; background: var(--neon-purple); bottom: 5%; right: -15%; }
.bg-glow-orb.green { width: 400px; height: 400px; background: var(--neon-green); top: 50%; left: 40%; opacity: 0.2; }

/* Reveal: JS adds .reveal-init BEFORE observing; without JS everything stays visible (no-FOUC) */
.reveal { opacity: 1; transform: none; transition: opacity 0.8s ease, transform 0.8s ease; }
.reveal.reveal-init { opacity: 0; transform: translateY(40px); }
.reveal.in-view { 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; }

/* Safety: if JS disabled or hasn't hydrated yet, ensure visibility after 1.2s */
@media (prefers-reduced-motion: no-preference) {
  .reveal { will-change: opacity, transform; }
}

.divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--neon-cyan), transparent);
  margin: 60px auto;
  max-width: 300px;
}
.badge {
  display: inline-block;
  padding: 4px 10px;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 1px;
  border-radius: 4px;
  background: rgba(0, 240, 255, 0.1);
  border: 1px solid var(--border-glow);
  color: var(--neon-cyan);
  text-transform: uppercase;
}

/* Forms */
.form-group { margin-bottom: 20px; }
.form-group label {
  display: block; font-family: var(--font-mono);
  font-size: 0.78rem; letter-spacing: 1.5px;
  color: var(--neon-cyan); text-transform: uppercase;
  margin-bottom: 8px;
}
.form-control {
  width: 100%;
  padding: 14px 18px;
  background: rgba(10, 14, 39, 0.6);
  border: 1px solid var(--border-soft);
  border-radius: 8px;
  color: var(--text-1);
  font-family: var(--font-body);
  font-size: 0.95rem;
  transition: all 0.3s ease;
}
.form-control:focus {
  outline: none;
  border-color: var(--neon-cyan);
  background: rgba(10, 14, 39, 0.9);
  box-shadow: 0 0 0 3px rgba(0, 240, 255, 0.15);
}
textarea.form-control { min-height: 140px; resize: vertical; font-family: var(--font-mono); }
select.form-control { appearance: none; cursor: pointer; }

.skip-link {
  position: absolute; left: -9999px; top: 0;
  padding: 8px 16px; background: var(--neon-cyan);
  color: var(--bg-0); font-weight: 700; z-index: 9999;
}
.skip-link:focus { left: 16px; top: 16px; }