/* ==========================================================================
   huixinhvac.com — Global stylesheet
   Desktop design width: 1440px · content width: 1200px
   Tokens: navy #061E33 / primary #0E5A9E / accent #00A0E9
   ========================================================================== */

:root{
  --navy900:#061E33;
  --navy800:#0A2C4D;
  --primary:#0E5A9E;
  --primary-d:#0A4780;
  --accent:#00A0E9;
  --sky:#EFF6FC;
  --bg:#F5F8FB;
  --ink:#14273A;
  --secondary:#5A7186;
  --line:#DCE6F0;
  --white:#fff;
  --radius:12px;
  --shadow-sm:0 2px 8px rgba(6,30,51,.06);
  --shadow:0 4px 18px rgba(6,30,51,.09);
  --shadow-lg:0 12px 40px rgba(6,30,51,.14);
  --font-head:'Barlow',Inter,'Segoe UI',Helvetica,Arial,sans-serif;
  --font-body:Inter,'Segoe UI',-apple-system,BlinkMacSystemFont,Helvetica,Arial,sans-serif;
  --font-mono:'Roboto Mono',Consolas,'Courier New',monospace;
}

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

html{scroll-behavior:smooth}

body{
  font-family:var(--font-body);
  font-size:16px;
  line-height:1.65;
  color:var(--ink);
  background:var(--white);
  -webkit-font-smoothing:antialiased;
}

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

a{color:var(--primary);text-decoration:none;transition:color .16s ease}
a:hover{color:var(--primary-d)}

h1,h2,h3,h4{font-family:var(--font-head);font-weight:600;line-height:1.18;letter-spacing:-.2px;color:var(--navy900)}
h1{font-size:52px;font-weight:700}
h2{font-size:36px}
h3{font-size:22px}
h4{font-size:18px}
p{color:var(--secondary)}

.container{width:100%;max-width:1200px;margin:0 auto;padding:0 24px}
.section{padding:80px 0}
.section--tint{background:var(--bg)}
.section--sky{background:var(--sky)}
.section--navy{background:var(--navy900);color:rgba(255,255,255,.82)}
.section--navy h2,.section--navy h3{color:#fff}
.section--navy p{color:rgba(255,255,255,.72)}

/* ---------- Eyebrow / section header ---------- */
.eyebrow{
  display:inline-block;font-family:var(--font-body);font-size:12px;font-weight:600;
  letter-spacing:1.4px;text-transform:uppercase;color:var(--accent);margin-bottom:12px;
}
.eyebrow::before{content:'';display:inline-block;width:22px;height:2px;background:var(--accent);vertical-align:middle;margin-right:9px}
.section-head{max-width:760px;margin-bottom:44px}
.section-head h2{margin-bottom:14px}
.section-head p{font-size:17px}
.section-head--center{margin-left:auto;margin-right:auto;text-align:center}

/* ---------- Top bar ---------- */
.topbar{background:var(--navy900);border-bottom:1px solid rgba(255,255,255,.09);font-size:13px}
.topbar .container{display:flex;align-items:center;justify-content:space-between;gap:16px;height:38px;flex-wrap:wrap}
.topbar span,.topbar a{color:#9FBBD4}
.topbar a:hover{color:#fff}
.topbar .tags{display:flex;gap:14px;align-items:center;flex-wrap:wrap}
.topbar .tag{color:var(--accent);font-weight:600;letter-spacing:.4px}
.topbar .contacts{display:flex;gap:18px;flex-wrap:wrap}

/* ---------- Navigation ---------- */
.nav{position:sticky;top:0;z-index:100;background:#fff;border-bottom:1px solid var(--line);box-shadow:0 1px 3px rgba(6,30,51,.04)}
.nav .container{display:flex;align-items:center;gap:28px;height:70px}
.logo{display:flex;align-items:center;gap:10px;flex-shrink:0}
.logo .mark{
  width:34px;height:34px;border-radius:8px;background:linear-gradient(135deg,var(--primary),var(--accent));
  display:flex;align-items:center;justify-content:center;color:#fff;font-family:var(--font-head);
  font-weight:700;font-size:15px;letter-spacing:.5px;
}
.logo .txt{font-family:var(--font-head);font-size:17px;font-weight:700;color:var(--navy900);line-height:1.1}
.logo .txt small{display:block;font-family:var(--font-body);font-size:11px;font-weight:500;color:var(--secondary);letter-spacing:.6px}
.menu{display:flex;gap:4px;margin-left:auto;align-items:center}
.menu a{font-size:14.5px;font-weight:500;color:var(--ink);padding:9px 13px;border-radius:8px;white-space:nowrap}
.menu a:hover{background:var(--sky);color:var(--primary)}
.menu a.active{color:var(--primary);font-weight:600}
.menu .has-sub{position:relative}
.menu .has-sub > a::after{content:'▾';font-size:9px;margin-left:5px;color:var(--secondary);vertical-align:2px}
.submenu{
  position:absolute;top:100%;left:0;min-width:250px;background:#fff;border:1px solid var(--line);
  border-radius:10px;box-shadow:var(--shadow);padding:8px;display:none;
}
.has-sub:hover .submenu{display:block}
.submenu a{display:block;font-size:14px;padding:8px 11px;color:var(--ink)}
.submenu a small{display:block;font-size:12px;color:var(--secondary);font-weight:400}
.nav-toggle{display:none;margin-left:auto;background:none;border:1px solid var(--line);border-radius:8px;width:42px;height:38px;cursor:pointer;font-size:18px;color:var(--navy900);line-height:1}

/* ---------- Buttons ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;
  font-family:var(--font-body);font-size:14.5px;font-weight:600;
  padding:12px 22px;border-radius:8px;border:1px solid transparent;cursor:pointer;
  text-decoration:none;transition:all .16s ease;white-space:nowrap;
}
.btn--primary{background:var(--primary);color:#fff}
.btn--primary:hover{background:var(--primary-d);color:#fff;transform:translateY(-1px);box-shadow:var(--shadow)}
.btn--accent{background:var(--accent);color:#fff}
.btn--accent:hover{background:#0090d1;color:#fff}
.btn--ghost{background:transparent;border-color:rgba(255,255,255,.5);color:#fff}
.btn--ghost:hover{background:rgba(255,255,255,.12);color:#fff}
.btn--outline{background:#fff;border-color:var(--line);color:var(--navy900)}
.btn--outline:hover{border-color:var(--primary);color:var(--primary)}
.btn--sm{padding:9px 16px;font-size:13.5px}
.btn-row{display:flex;gap:14px;flex-wrap:wrap;margin-top:30px}

/* ---------- Hero ---------- */
.hero{position:relative;background:var(--navy900);color:#fff;overflow:hidden}
.hero__bg{position:absolute;inset:0}
.hero__bg img{width:100%;height:100%;object-fit:cover;opacity:.34}
.hero__bg::after{content:'';position:absolute;inset:0;background:linear-gradient(100deg,rgba(6,30,51,.94) 18%,rgba(6,30,51,.72) 62%,rgba(6,30,51,.5))}
.hero .container{position:relative;z-index:2;padding-top:96px;padding-bottom:96px}
.hero h1{color:#fff;max-width:840px;margin-bottom:20px}
.hero h1 em{font-style:normal;color:var(--accent)}
.hero p{color:rgba(255,255,255,.78);font-size:19px;max-width:720px}
.hero__chips{display:flex;gap:10px;flex-wrap:wrap;margin-top:26px}
.chip{
  background:rgba(255,255,255,.1);border:1px solid rgba(255,255,255,.22);color:#fff;
  font-size:13px;font-weight:500;padding:6px 13px;border-radius:20px;
}
.chip--mono{font-family:var(--font-mono);font-size:12.5px}
.hero__stats{display:grid;grid-template-columns:repeat(3,1fr);gap:24px;margin-top:56px;max-width:820px;border-top:1px solid rgba(255,255,255,.16);padding-top:28px}
.hero__stats div b{display:block;font-family:var(--font-head);font-size:34px;font-weight:700;color:#fff;line-height:1.1}
.hero__stats div span{font-size:13.5px;color:rgba(255,255,255,.66)}

/* ---------- Page hero (inner pages) ---------- */
.phero{background:linear-gradient(135deg,var(--navy900),var(--navy800));color:#fff;padding:64px 0 70px}
.phero h1{color:#fff;max-width:840px;font-size:44px;margin-bottom:16px}
.phero p{color:rgba(255,255,255,.74);font-size:18px;max-width:760px}
.breadcrumb{font-size:13px;color:rgba(255,255,255,.6);margin-bottom:16px}
.breadcrumb a{color:rgba(255,255,255,.75)}
.breadcrumb a:hover{color:#fff}

/* ---------- Trust strip ---------- */
.trust{background:var(--sky);border-bottom:1px solid var(--line);padding:26px 0}
.trust .container{display:flex;align-items:center;justify-content:space-between;gap:26px;flex-wrap:wrap}
.trust .item{display:flex;align-items:center;gap:9px;font-size:13.5px;font-weight:600;color:var(--navy800)}
.trust .item::before{content:'✓';color:var(--accent);font-weight:700;font-size:14px}

/* ---------- Grids ---------- */
.grid{display:grid;gap:24px}
.grid--3{grid-template-columns:repeat(3,1fr)}
.grid--4{grid-template-columns:repeat(4,1fr)}
.grid--2{grid-template-columns:repeat(2,1fr)}

/* ---------- Cards ---------- */
.card{
  background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;
  box-shadow:var(--shadow-sm);transition:transform .18s ease,box-shadow .18s ease;display:flex;flex-direction:column;
}
.card:hover{transform:translateY(-3px);box-shadow:var(--shadow)}
.card__img{height:190px;overflow:hidden;background:var(--sky)}
.card__img img{width:100%;height:100%;object-fit:cover}
.card__body{padding:22px;display:flex;flex-direction:column;flex:1}
.card__body h3{margin-bottom:8px;font-size:19px}
.card__body p{font-size:14.5px;line-height:1.6;flex:1}
.card__meta{font-family:var(--font-mono);font-size:12.5px;color:var(--primary);margin-bottom:6px;font-weight:500}
.card__list{list-style:none;margin:14px 0 0;font-size:14px}
.card__list li{padding-left:18px;position:relative;color:var(--secondary);margin-bottom:6px}
.card__list li::before{content:'';position:absolute;left:0;top:9px;width:6px;height:6px;border-radius:50%;background:var(--accent)}
.link-more{display:inline-block;margin-top:16px;font-size:14px;font-weight:600;color:var(--primary)}
.link-more:hover{color:var(--accent)}

/* Feature card (no image) */
.fcard{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:26px;box-shadow:var(--shadow-sm)}
.fcard .num{
  width:38px;height:38px;border-radius:9px;background:var(--sky);color:var(--primary);
  display:flex;align-items:center;justify-content:center;font-family:var(--font-head);
  font-weight:700;font-size:16px;margin-bottom:14px;
}
.fcard h3{font-size:18px;margin-bottom:8px}
.fcard p{font-size:14.5px}

/* Stat card */
.stat{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:26px;text-align:center}
.stat b{display:block;font-family:var(--font-head);font-size:38px;font-weight:700;color:var(--primary);line-height:1.05}
.stat span{font-size:13.5px;color:var(--secondary)}

/* Mini card (navy section) */
.mini{background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.12);border-radius:var(--radius);padding:24px}
.mini h3{font-size:18px;margin-bottom:8px}
.mini p{font-size:14px}

/* ---------- Spec table ---------- */
.table-wrap{background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow-x:auto;box-shadow:var(--shadow-sm)}
table{width:100%;border-collapse:collapse;font-size:14.5px;min-width:720px}
thead th{
  background:var(--navy900);color:#fff;text-align:left;padding:14px 18px;
  font-family:var(--font-head);font-size:13.5px;font-weight:600;letter-spacing:.3px;white-space:nowrap;
}
tbody td{padding:14px 18px;border-bottom:1px solid var(--line);color:var(--secondary)}
tbody tr:last-child td{border-bottom:none}
tbody tr:hover td{background:var(--bg)}
tbody td:first-child{font-weight:600;color:var(--ink);font-family:var(--font-body)}
td.mono,th.mono{font-family:var(--font-mono);font-size:13.5px}
.tag-yes{color:#0E7A45;font-weight:600}
.tag-opt{color:var(--secondary);font-weight:600}

/* ---------- Steps ---------- */
.steps{display:grid;grid-template-columns:repeat(4,1fr);gap:24px;counter-reset:s}
.step{position:relative;padding-top:14px}
.step::before{
  counter-increment:s;content:counter(s);
  display:flex;align-items:center;justify-content:center;width:42px;height:42px;border-radius:50%;
  background:var(--primary);color:#fff;font-family:var(--font-head);font-weight:700;font-size:18px;margin-bottom:16px;
}
.step h3{font-size:18px;margin-bottom:8px}
.step p{font-size:14.5px}

/* ---------- Split (image + text) ---------- */
.split{display:grid;grid-template-columns:1fr 1fr;gap:56px;align-items:center}
.split__img{border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow)}
.split__img img{width:100%;height:400px;object-fit:cover}
.split h2{margin-bottom:16px}
.split p + p{margin-top:12px}
.bullets{list-style:none;margin-top:20px}
.bullets li{position:relative;padding-left:28px;margin-bottom:12px;font-size:15px;color:var(--secondary)}
.bullets li::before{content:'✓';position:absolute;left:0;top:0;width:20px;height:20px;border-radius:50%;background:var(--sky);color:var(--primary);font-size:11px;display:flex;align-items:center;justify-content:center;font-weight:700}
.bullets li b{color:var(--ink);font-weight:600}

/* ---------- FAQ ---------- */
.faq{max-width:860px}
.faq details{border:1px solid var(--line);border-radius:10px;margin-bottom:12px;background:#fff;overflow:hidden}
.faq summary{
  padding:18px 22px;font-family:var(--font-head);font-size:17px;font-weight:600;color:var(--navy900);
  cursor:pointer;list-style:none;display:flex;justify-content:space-between;align-items:center;gap:16px;
}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:'+';font-size:22px;color:var(--accent);font-weight:400;line-height:1}
.faq details[open] summary::after{content:'–'}
.faq details[open] summary{border-bottom:1px solid var(--line)}
.faq .answer{padding:18px 22px;font-size:15px;color:var(--secondary)}
.faq .answer p + p{margin-top:10px}

/* ---------- CTA banner ---------- */
.cta{background:linear-gradient(120deg,var(--primary),var(--navy800));color:#fff;padding:66px 0;text-align:center}
.cta h2{color:#fff;margin-bottom:14px}
.cta p{color:rgba(255,255,255,.8);font-size:18px;max-width:680px;margin:0 auto}
.cta .btn-row{justify-content:center;margin-top:28px}
.cta .btn--ghost{border-color:rgba(255,255,255,.55)}

/* ---------- Contact form ---------- */
.form-layout{display:grid;grid-template-columns:1.25fr .75fr;gap:40px;align-items:start}
.form-card{background:#fff;border:1px solid var(--line);border-radius:var(--radius);padding:34px;box-shadow:var(--shadow)}
.form-card h2{font-size:26px;margin-bottom:6px}
.form-row{display:grid;grid-template-columns:1fr 1fr;gap:18px}
.field{margin-top:18px}
.field label{display:block;font-size:13.5px;font-weight:600;color:var(--ink);margin-bottom:7px}
.field label span{color:var(--accent)}
.field input,.field select,.field textarea{
  width:100%;font-family:var(--font-body);font-size:14.5px;color:var(--ink);
  padding:11px 14px;border:1px solid var(--line);border-radius:8px;background:#fff;transition:border-color .15s;
}
.field input:focus,.field select:focus,.field textarea:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px rgba(0,160,233,.12)}
.field textarea{min-height:120px;resize:vertical}
.form-note{font-size:12.5px;color:var(--secondary);margin-top:16px}
.form-status{margin-top:18px;padding:13px 16px;border-radius:8px;font-size:14px;font-weight:500}
.form-status.ok{background:#E9F7F0;border:1px solid #BFE3D0;color:#0E7A45}
.form-status.err{background:#FDECEC;border:1px solid #F5C6C6;color:#A02626}
.form-card .btn{width:100%;margin-top:24px}

.aside-card{background:var(--bg);border:1px solid var(--line);border-radius:var(--radius);padding:28px;margin-bottom:24px}
.aside-card h3{font-size:19px;margin-bottom:14px}
.aside-card ul{list-style:none}
.aside-card li{font-size:14.5px;color:var(--secondary);padding-left:26px;position:relative;margin-bottom:12px}
.aside-card li b{display:block;color:var(--ink);font-size:14px}
.aside-card li .n{
  position:absolute;left:0;top:1px;width:18px;height:18px;border-radius:50%;background:var(--primary);
  color:#fff;font-size:11px;font-weight:700;display:flex;align-items:center;justify-content:center;
}
.contact-line{display:flex;gap:12px;align-items:flex-start;margin-bottom:16px;font-size:14.5px}
.contact-line .ic{width:34px;height:34px;border-radius:8px;background:var(--sky);color:var(--primary);display:flex;align-items:center;justify-content:center;font-size:15px;flex-shrink:0}
.contact-line b{display:block;color:var(--ink);font-size:13px;font-weight:600}
.contact-line a,.contact-line span{color:var(--secondary);font-size:14.5px}

/* ---------- Insights / blog cards ---------- */
.post{background:#fff;border:1px solid var(--line);border-radius:var(--radius);overflow:hidden;box-shadow:var(--shadow-sm)}
.post__img{height:170px;overflow:hidden}
.post__img img{width:100%;height:100%;object-fit:cover}
.post__body{padding:22px}
.post__meta{font-size:12px;font-weight:600;color:var(--accent);letter-spacing:.6px;text-transform:uppercase;margin-bottom:8px}
.post__body h3{font-size:18px;margin-bottom:8px}
.post__body p{font-size:14px}

/* ---------- Footer ---------- */
.footer{background:var(--navy900);color:rgba(255,255,255,.68);padding:64px 0 0}
.footer__grid{display:grid;grid-template-columns:1.6fr 1fr 1fr 1fr 1.2fr;gap:40px}
.footer h4{color:#fff;font-size:13px;font-weight:600;letter-spacing:1px;text-transform:uppercase;margin-bottom:16px}
.footer ul{list-style:none}
.footer li{margin-bottom:10px;font-size:14px}
.footer a{color:rgba(255,255,255,.68)}
.footer a:hover{color:#fff}
.footer .about p{font-size:14px;color:rgba(255,255,255,.6);margin-top:14px;max-width:300px}
.footer .about .logo{margin-bottom:4px}
.footer .about .logo .txt{color:#fff}
.footer .about .logo .txt small{color:rgba(255,255,255,.5)}
.footer__bottom{border-top:1px solid rgba(255,255,255,.12);margin-top:48px;padding:22px 0;font-size:13px;display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;color:rgba(255,255,255,.5)}
.footer__bottom a{color:rgba(255,255,255,.55)}

/* ---------- Responsive ---------- */
@media (max-width:1100px){
  .grid--4{grid-template-columns:repeat(2,1fr)}
  .footer__grid{grid-template-columns:1fr 1fr 1fr}
  .steps{grid-template-columns:repeat(2,1fr)}
}
@media (max-width:900px){
  h1{font-size:40px}
  h2{font-size:30px}
  .phero h1{font-size:34px}
  .nav .container{height:62px}
  .nav-toggle{display:block}
  .menu{
    display:none;position:absolute;top:100%;left:0;right:0;background:#fff;
    border-bottom:1px solid var(--line);flex-direction:column;align-items:stretch;gap:0;padding:10px 24px 18px;
    box-shadow:var(--shadow);max-height:70vh;overflow-y:auto;
  }
  .menu.open{display:flex}
  .menu a{padding:12px 0;border-bottom:1px solid var(--line);font-size:15px}
  .menu .btn{margin-top:14px}
  .submenu{position:static;display:none;border:none;box-shadow:none;padding:0 0 0 12px;min-width:0}
  .has-sub:hover .submenu{display:none}
  .has-sub.open .submenu{display:block}
  .split{grid-template-columns:1fr;gap:32px}
  .form-layout{grid-template-columns:1fr}
  .hero__stats{grid-template-columns:1fr;gap:18px}
  .hero__stats div b{font-size:28px}
}
@media (max-width:640px){
  .section{padding:56px 0}
  .grid--3,.grid--2,.grid--4{grid-template-columns:1fr}
  .steps{grid-template-columns:1fr}
  .form-row{grid-template-columns:1fr}
  .footer__grid{grid-template-columns:1fr 1fr}
  .topbar .contacts{display:none}
  .hero{padding-top:0}
  .hero .container{padding-top:60px;padding-bottom:60px}
  .hero h1{font-size:32px}
  .hero p{font-size:16px}
  .cta{padding:48px 0}
  .form-card{padding:24px}
}