/* =========================================================
   Fog Bubble Machines — Bilingual Site Styles
   Palette: deep navy + cyan accent, clean modern B2B
   ========================================================= */

:root {
  --navy-900: #08182e;
  --navy-800: #0a2540;
  --navy-700: #102a43;
  --navy-600: #1a3a5c;
  --cyan-500: #00b4d8;
  --cyan-400: #2bc4e0;
  --cyan-300: #7fdcec;
  --ink: #1a2b42;
  --muted: #5b6b82;
  --line: #e3e9f2;
  --bg-soft: #f5f8fc;
  --white: #ffffff;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(10, 37, 64, 0.08);
  --shadow-lg: 0 18px 50px rgba(10, 37, 64, 0.14);
  --maxw: 1180px;
  --font: "Inter", "Segoe UI", "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--white);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

/* language block toggling */
html:not(.lang-zh) .lang-zh { display: none; }
html.lang-zh .lang-en { display: none; }

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

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

.container { width: 100%; max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-block;
  padding: 13px 28px;
  border-radius: 999px;
  font-weight: 600;
  font-size: 15px;
  letter-spacing: .2px;
  cursor: pointer;
  border: 2px solid transparent;
  transition: transform .15s ease, box-shadow .2s ease, background .2s ease;
}
.btn-primary { background: var(--cyan-500); color: #04222e; }
.btn-primary:hover { background: var(--cyan-400); transform: translateY(-2px); box-shadow: 0 10px 24px rgba(0,180,216,.35); }
.btn-ghost { background: transparent; color: #fff; border-color: rgba(255,255,255,.7); }
.btn-ghost:hover { background: rgba(255,255,255,.12); border-color: #fff; }

/* ---------- Header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 100;
  background: rgba(8, 24, 46, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid rgba(255,255,255,.06);
  transition: box-shadow .25s ease, background .25s ease;
}
.site-header.scrolled { box-shadow: 0 6px 24px rgba(0,0,0,.25); }
.header-inner { display: flex; align-items: center; justify-content: space-between; height: 70px; }
.brand { display: flex; align-items: center; gap: 10px; color: #fff; }
.brand-mark { width: 34px; height: 34px; color: var(--cyan-400); }
.brand-text { font-weight: 800; font-size: 20px; letter-spacing: 1px; }

.main-nav { display: flex; gap: 30px; }
.main-nav a {
  color: rgba(255,255,255,.82); font-weight: 500; font-size: 15px;
  position: relative; padding: 6px 0; transition: color .2s;
}
.main-nav a:hover { color: #fff; }
.main-nav a::after {
  content: ""; position: absolute; left: 0; bottom: 0; height: 2px; width: 0;
  background: var(--cyan-400); transition: width .25s ease;
}
.main-nav a:hover::after { width: 100%; }

.header-actions { display: flex; align-items: center; gap: 14px; }
.lang-toggle {
  background: rgba(255,255,255,.1); color: #fff; border: 1px solid rgba(255,255,255,.25);
  padding: 8px 16px; border-radius: 999px; font-weight: 600; cursor: pointer; font-size: 14px;
  transition: background .2s;
}
.lang-toggle:hover { background: rgba(255,255,255,.2); }

.menu-toggle { display: none; flex-direction: column; gap: 5px; background: none; border: 0; cursor: pointer; padding: 6px; }
.menu-toggle span { width: 24px; height: 2px; background: #fff; border-radius: 2px; }

/* ---------- Hero ---------- */
.hero { position: relative; min-height: 78vh; display: flex; align-items: center; overflow: hidden; }
.hero-bg { position: absolute; inset: 0; background-size: cover; background-position: center; transform: scale(1.05); }
.hero-overlay { position: absolute; inset: 0; background: linear-gradient(105deg, rgba(8,24,46,.88) 0%, rgba(10,37,64,.55) 55%, rgba(10,37,64,.2) 100%); }
.hero-content { position: relative; z-index: 2; color: #fff; max-width: 720px; padding: 80px 0; }
.hero-eyebrow {
  display: inline-block; background: rgba(0,180,216,.18); color: var(--cyan-300);
  border: 1px solid rgba(0,180,216,.4); padding: 7px 16px; border-radius: 999px;
  font-size: 13px; font-weight: 600; letter-spacing: 1px; margin-bottom: 22px;
}
.hero-title { font-size: clamp(32px, 5vw, 56px); line-height: 1.12; font-weight: 800; margin-bottom: 20px; }
.hero-sub { font-size: clamp(15px, 2vw, 19px); color: rgba(255,255,255,.9); margin-bottom: 34px; max-width: 600px; }
.hero-cta { display: flex; gap: 16px; flex-wrap: wrap; }

/* ---------- Stats ---------- */
.stats { background: var(--navy-800); color: #fff; }
.stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; padding: 46px 24px; }
.stat { text-align: center; }
.stat-num { font-size: clamp(30px, 4vw, 46px); font-weight: 800; color: var(--cyan-400); }
.stat-label { font-size: 14px; color: rgba(255,255,255,.78); margin-top: 6px; letter-spacing: .3px; }

/* ---------- Sections ---------- */
.section { padding: 84px 0; }
.section-alt { background: var(--bg-soft); }
.section-head { text-align: center; max-width: 720px; margin: 0 auto 50px; }
.section-kicker { display: inline-block; color: var(--cyan-500); font-weight: 700; font-size: 14px; letter-spacing: 1.5px; text-transform: uppercase; margin-bottom: 12px; }
.section-title { font-size: clamp(26px, 3.4vw, 38px); font-weight: 800; color: var(--navy-800); margin-bottom: 14px; }
.section-desc { color: var(--muted); font-size: 16px; }

/* ---------- Categories ---------- */
.cat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.cat-card { background: #fff; border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); transition: transform .25s ease, box-shadow .25s ease; border: 1px solid var(--line); }
.cat-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); }
.cat-img { height: 220px; background-size: cover; background-position: center; }
.cat-body { padding: 24px; }
.cat-body h3 { font-size: 21px; color: var(--navy-800); margin-bottom: 10px; }
.cat-body p { color: var(--muted); font-size: 15px; margin-bottom: 16px; }
.cat-link { color: var(--cyan-500); font-weight: 700; font-size: 15px; }

/* ---------- Products ---------- */
.product-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 26px; }
.product-card { background: #fff; border-radius: var(--radius); overflow: hidden; box-shadow: var(--shadow); border: 1px solid var(--line); transition: transform .25s ease, box-shadow .25s ease; display: flex; flex-direction: column; }
.product-card:hover { transform: translateY(-6px); box-shadow: var(--shadow-lg); }
.product-img { height: 230px; background-size: cover; background-position: center; background-color: #eef3f8; }
.product-body { padding: 22px; display: flex; flex-direction: column; flex: 1; }
.product-model { display: inline-block; align-self: flex-start; background: var(--bg-soft); color: var(--navy-600); font-weight: 700; font-size: 13px; padding: 4px 12px; border-radius: 999px; margin-bottom: 12px; letter-spacing: .5px; }
.product-body h3 { font-size: 18px; color: var(--navy-800); margin-bottom: 8px; line-height: 1.35; }
.product-tag { color: var(--muted); font-size: 14px; margin-bottom: 16px; flex: 1; }
.product-link { color: var(--cyan-500); font-weight: 700; font-size: 15px; }

/* ---------- About ---------- */
.about-grid { display: grid; grid-template-columns: 1fr 1.1fr; gap: 50px; align-items: center; }
.about-img { height: 440px; border-radius: var(--radius); background-size: cover; background-position: center; box-shadow: var(--shadow); }
.about-text .section-kicker { margin-bottom: 10px; }
.about-text .section-title { text-align: left; margin-bottom: 18px; }
.about-text p { color: var(--muted); margin-bottom: 14px; font-size: 15.5px; }
.about-text .btn { margin-top: 10px; }

/* ---------- Why ---------- */
.why-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 28px; }
.why-card { background: #fff; border-radius: var(--radius); padding: 36px 30px; box-shadow: var(--shadow); border: 1px solid var(--line); text-align: center; transition: transform .25s ease; }
.why-card:hover { transform: translateY(-6px); }
.why-icon { width: 64px; height: 64px; margin: 0 auto 20px; border-radius: 16px; background: linear-gradient(135deg, var(--cyan-500), var(--cyan-300)); color: #04222e; display: flex; align-items: center; justify-content: center; font-size: 30px; font-weight: 800; }
.why-card h3 { font-size: 20px; color: var(--navy-800); margin-bottom: 12px; }
.why-card p { color: var(--muted); font-size: 15px; }

/* ---------- FAQ ---------- */
.faq-list { max-width: 820px; margin: 0 auto; }
.faq-item { background: #fff; border: 1px solid var(--line); border-radius: 12px; margin-bottom: 14px; overflow: hidden; }
.faq-q { width: 100%; text-align: left; background: none; border: 0; padding: 20px 24px; font-size: 17px; font-weight: 600; color: var(--navy-800); cursor: pointer; display: flex; justify-content: space-between; align-items: center; gap: 16px; }
.faq-plus { color: var(--cyan-500); font-size: 24px; font-weight: 400; transition: transform .2s ease; }
.faq-item.open .faq-plus { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height .3s ease; }
.faq-a > div { padding: 0 24px 22px; color: var(--muted); font-size: 15.5px; }

/* ---------- Contact ---------- */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 50px; align-items: start; }
.contact-info .section-kicker { margin-bottom: 10px; }
.contact-info .section-title { text-align: left; margin-bottom: 14px; }
.contact-list { list-style: none; margin-top: 26px; }
.contact-list li { display: flex; flex-direction: column; padding: 14px 0; border-bottom: 1px solid var(--line); }
.contact-list li span { color: var(--muted); font-size: 13px; text-transform: uppercase; letter-spacing: 1px; margin-bottom: 4px; }
.contact-list li strong { color: var(--navy-800); font-size: 16px; font-weight: 600; }
.contact-form { background: #fff; padding: 32px; border-radius: var(--radius); box-shadow: var(--shadow); border: 1px solid var(--line); }
.field { margin-bottom: 16px; }
.field input, .field textarea {
  width: 100%; padding: 13px 16px; border: 1px solid var(--line); border-radius: 10px;
  font-family: var(--font); font-size: 15px; color: var(--ink); background: #fff; transition: border .2s, box-shadow .2s;
}
.field input:focus, .field textarea:focus { outline: 0; border-color: var(--cyan-500); box-shadow: 0 0 0 3px rgba(0,180,216,.15); }
.field textarea { resize: vertical; }
.contact-form .btn { width: 100%; }

/* ---------- Footer ---------- */
.site-footer { background: var(--navy-900); color: rgba(255,255,255,.8); padding: 60px 0 0; }
.footer-grid { display: grid; grid-template-columns: 1.6fr 1fr 1fr 1fr; gap: 36px; padding-bottom: 40px; }
.footer-col h4 { color: #fff; font-size: 16px; margin-bottom: 18px; font-weight: 700; }
.footer-col a, .footer-col span { display: block; color: rgba(255,255,255,.7); font-size: 14.5px; margin-bottom: 11px; transition: color .2s; }
.footer-col a:hover { color: var(--cyan-400); }
.footer-brand p { color: rgba(255,255,255,.65); font-size: 14px; margin-top: 14px; max-width: 280px; }
.footer-bottom { border-top: 1px solid rgba(255,255,255,.1); padding: 20px 0; text-align: center; font-size: 13.5px; color: rgba(255,255,255,.55); }

/* ---------- Responsive ---------- */
@media (max-width: 980px) {
  .cat-grid, .product-grid, .why-grid { grid-template-columns: repeat(2, 1fr); }
  .about-grid, .contact-grid { grid-template-columns: 1fr; gap: 34px; }
  .about-img { height: 320px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 720px) {
  .main-nav {
    position: fixed; top: 70px; right: 0; width: 240px; height: calc(100vh - 70px);
    background: var(--navy-800); flex-direction: column; gap: 0; padding: 20px 0;
    transform: translateX(100%); transition: transform .3s ease; box-shadow: -10px 0 30px rgba(0,0,0,.3);
  }
  .main-nav.open { transform: translateX(0); }
  .main-nav a { padding: 14px 24px; border-bottom: 1px solid rgba(255,255,255,.07); }
  .menu-toggle { display: flex; }
  .stats-grid { grid-template-columns: repeat(2, 1fr); gap: 26px 10px; }
  .cat-grid, .product-grid, .why-grid { grid-template-columns: 1fr; }
  .footer-grid { grid-template-columns: 1fr; }
  .section { padding: 60px 0; }
  .hero { min-height: 70vh; }
  .hero-content { padding: 60px 0; }
}