/* ===== Design tokens (light, energy theme) ===== */
:root {
  --bg: #ffffff;
  --bg-alt: #f4f8fc;
  --text: #0f172a;
  --text-soft: #475569;
  --primary: #2563eb;
  --primary-700: #1d4ed8;
  --accent: #10b981;
  --border: #e2e8f0;
  --radius: 16px;
  --shadow: 0 10px 30px rgba(15, 23, 42, 0.08);
  --container: 1140px;
  --header-h: 64px;
}

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-h) + 12px);
}

body {
  margin: 0;
  font-family: "Segoe UI", system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

img, svg { max-width: 100%; display: block; }

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

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 20px;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 22px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 15px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
}
.btn:active { transform: translateY(1px); }
.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.3);
}
.btn-primary:hover { box-shadow: 0 12px 26px rgba(37, 99, 235, 0.4); }
.btn-ghost {
  background: #fff;
  border-color: var(--border);
  color: var(--text);
}
.btn-ghost:hover { border-color: var(--primary); color: var(--primary); }
.btn-block { width: 100%; }

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid transparent;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.site-header.scrolled { border-bottom-color: var(--border); box-shadow: 0 4px 18px rgba(15, 23, 42, 0.06); }
.nav-inner { height: var(--header-h); display: flex; align-items: center; justify-content: space-between; }
.brand { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; font-size: 18px; letter-spacing: 0.02em; }
.brand-mark {
  width: 34px; height: 34px;
  display: grid; place-items: center;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff; font-size: 17px; font-weight: 800;
}
.brand-sub { color: var(--primary); margin-left: 4px; font-weight: 700; }
.nav-links { display: flex; align-items: center; gap: 24px; }
.nav-links a { color: var(--text-soft); font-size: 15px; font-weight: 500; }
.nav-links a:hover { color: var(--text); }
.nav-cta { color: #fff !important; padding: 9px 18px; }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  width: 42px; height: 42px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: #fff;
  cursor: pointer;
}
.nav-toggle span {
  display: block; width: 20px; height: 2px; margin: 0 auto;
  background: var(--text); border-radius: 2px;
  transition: transform 0.2s ease, opacity 0.2s ease;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav-toggle[aria-expanded="true"] span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ===== Hero ===== */
.hero {
  padding: 72px 0 64px;
  background: radial-gradient(1200px 500px at 80% -10%, #e8f1ff 0%, rgba(232,241,255,0) 60%);
}
.hero-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 40px; align-items: center; }
.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 13px;
  font-weight: 700;
  color: var(--primary);
  margin: 0 0 12px;
}
.hero h1 { font-size: clamp(30px, 5vw, 48px); line-height: 1.15; margin: 0 0 16px; letter-spacing: -0.01em; }
.lead { font-size: 18px; color: var(--text-soft); margin: 0 0 26px; max-width: 540px; }
.hero-actions { display: flex; gap: 14px; flex-wrap: wrap; }
.hero-badges {
  list-style: none; padding: 0; margin: 28px 0 0;
  display: flex; gap: 18px; flex-wrap: wrap;
  color: var(--text-soft); font-size: 14px; font-weight: 500;
}
.hero-art { display: grid; place-items: center; }

/* ===== Sections ===== */
.section { padding: 72px 0; }
.section-alt { background: var(--bg-alt); }
.section-head { text-align: center; max-width: 700px; margin: 0 auto 44px; }
.section-head h2 { font-size: clamp(24px, 3.4vw, 34px); margin: 0 0 12px; }
.section-sub { color: var(--text-soft); font-size: 17px; margin: 0; }

.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.grid-4 { display: grid; grid-template-columns: repeat(4, 1fr); gap: 22px; }

/* ===== Cards ===== */
.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 24px;
  box-shadow: var(--shadow);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  display: flex;
  flex-direction: column;
}
.card:hover { transform: translateY(-4px); box-shadow: 0 16px 36px rgba(15,23,42,0.12); }
.card-icon {
  width: 52px; height: 52px;
  display: grid; place-items: center;
  border-radius: 14px;
  background: #e8f1ff; color: var(--primary);
  margin-bottom: 16px;
}
.card h3 { margin: 0 0 8px; font-size: 18px; }
.card > p { margin: 0 0 12px; color: var(--text-soft); }
.spec { list-style: none; padding: 12px 0 0; margin: auto 0 0; border-top: 1px solid var(--border); display: grid; gap: 6px; }
.spec li { position: relative; padding-left: 20px; font-size: 14px; color: var(--text); }
.spec li::before { content: "▹"; position: absolute; left: 0; top: 0; color: var(--accent); font-weight: 700; }
.model-tag {
  display: inline-block;
  align-self: flex-start;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--primary-700);
  background: #e8f1ff;
  border: 1px solid #c7dcff;
  border-radius: 999px;
  padding: 3px 10px;
  margin-bottom: 12px;
}

/* ===== About ===== */
.about-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 48px; align-items: center; }
.about-copy h2 { font-size: clamp(22px, 3vw, 30px); margin: 0 0 14px; }
.about-copy p { color: var(--text-soft); margin: 0 0 16px; }
.about-copy .btn { margin-top: 6px; }
.about-points { list-style: none; padding: 0; margin: 0; display: grid; gap: 14px; }
.about-points li {
  background: #fff; border: 1px solid var(--border);
  border-radius: 12px; padding: 14px 16px; box-shadow: var(--shadow);
}
.about-points strong { color: var(--primary); }

/* ===== Stats ===== */
.stats { background: linear-gradient(135deg, var(--primary), var(--accent)); color: #fff; }
.stat { text-align: center; }
.stat-num { font-size: clamp(30px, 4vw, 44px); font-weight: 800; line-height: 1; }
.stat-label { margin-top: 8px; opacity: 0.92; font-size: 15px; }

/* ===== Applications chips ===== */
.chips { display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; }
.chip {
  background: #fff; border: 1px solid var(--border);
  border-radius: 999px; padding: 10px 18px;
  font-weight: 600; color: var(--text-soft);
  box-shadow: var(--shadow);
}

/* ===== Contact ===== */
.contact-inner { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: start; }
.contact-list { list-style: none; padding: 0; margin: 22px 0 0; display: grid; gap: 10px; color: var(--text-soft); }
.contact-list a { color: var(--primary); }
.contact-list em { color: #94a3b8; font-style: normal; font-size: 13px; }
.contact-form {
  background: #fff; border: 1px solid var(--border);
  border-radius: var(--radius); padding: 28px; box-shadow: var(--shadow);
}
.field { margin-bottom: 18px; }
.field label { display: block; font-weight: 600; margin-bottom: 6px; font-size: 14px; }
.req { color: #ef4444; }
.field input, .field textarea, .field select {
  width: 100%; padding: 12px 14px;
  border: 1px solid var(--border); border-radius: 10px;
  font-size: 15px; font-family: inherit; color: var(--text);
  background: #fff; transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
.field input:focus, .field textarea:focus, .field select:focus {
  outline: none; border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(37,99,235,0.15);
}
.field textarea { resize: vertical; }
.error { display: block; color: #ef4444; font-size: 13px; margin-top: 6px; min-height: 1px; }
.field.invalid input, .field.invalid textarea, .field.invalid select { border-color: #ef4444; }
.form-ok { color: #16a34a; font-weight: 600; margin: 14px 0 0; text-align: center; }

/* ===== Footer ===== */
.site-footer { background: #0f172a; color: #cbd5e1; padding: 48px 0 24px; }
.footer-inner { display: flex; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.footer-brand .brand-name { color: #fff; font-weight: 800; }
.footer-brand .brand-sub { color: #60a5fa; }
.footer-brand p { margin: 10px 0 0; color: #94a3b8; }
.footer-links { display: flex; gap: 22px; flex-wrap: wrap; align-items: center; }
.footer-links a { color: #cbd5e1; }
.footer-links a:hover { color: #fff; }
.footer-bottom {
  display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap;
  margin-top: 28px; padding-top: 18px; border-top: 1px solid #1e293b;
  font-size: 14px; color: #94a3b8;
}
.footer-bottom a { color: #94a3b8; }
.footer-bottom a:hover { color: #fff; }

/* ===== Reveal animation ===== */
.reveal { opacity: 0; transform: translateY(18px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.is-visible { opacity: 1; transform: none; }
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  html { scroll-behavior: auto; }
}

/* ===== Responsive ===== */
@media (max-width: 900px) {
  .hero-inner, .about-inner, .contact-inner { grid-template-columns: 1fr; }
  .hero-art { order: -1; }
  .grid-3 { grid-template-columns: 1fr 1fr; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 680px) {
  .nav-links {
    position: absolute;
    top: var(--header-h);
    left: 0; right: 0;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: #fff;
    border-bottom: 1px solid var(--border);
    box-shadow: 0 12px 24px rgba(15,23,42,0.1);
    padding: 8px 16px 16px;
    transform: translateY(-12px);
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease, transform 0.2s ease;
  }
  .nav-links.open { transform: none; opacity: 1; pointer-events: auto; }
  .nav-links a { padding: 12px 4px; border-bottom: 1px solid var(--border); }
  .nav-cta { border-bottom: none !important; margin-top: 10px; text-align: center; }
  .nav-toggle { display: flex; }
  .hero { padding: 48px 0 44px; }
  .section { padding: 56px 0; }
  .grid-3, .grid-4 { grid-template-columns: 1fr; }
}

@media (max-width: 420px) {
  .hero-actions .btn { flex: 1 1 100%; }
}