/* ===================================================================
   Sierra Automobile CO — site styles
   Dark industrial. Black + Sierra red. System fonts for instant load.
   =================================================================== */

:root{
  --bg:        #0a0a0c;
  --bg-2:      #111114;
  --surface:   #16161b;
  --surface-2: #1d1d23;
  --line:      #2a2a32;
  --line-2:    #3a3a44;
  --text:      #f4f4f6;
  --muted:     #9a9aa6;
  --muted-2:   #6e6e7a;
  --red:       #e62619;
  --red-deep:  #b81b10;
  --red-soft:  rgba(230,38,25,.12);
  --maxw:      1180px;
  --radius:    6px;
  --ease:      cubic-bezier(.22,.61,.36,1);
}

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

html{ scroll-behavior:smooth; -webkit-text-size-adjust:100%; }

body{
  background:var(--bg);
  color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,"PingFang TC","Noto Sans TC",sans-serif;
  font-size:17px;
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
  overflow-x:hidden;
}

img{ max-width:100%; display:block; }
a{ color:inherit; text-decoration:none; }

h1,h2,h3,h4{ line-height:1.1; font-weight:800; letter-spacing:-.01em; }

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

.eyebrow{
  display:inline-block;
  font-size:12.5px; font-weight:700; letter-spacing:.22em; text-transform:uppercase;
  color:var(--red); margin-bottom:18px;
}
.eyebrow.muted{ color:var(--muted-2); }

.section{ padding:96px 0; }
.section-tight{ padding:64px 0; }
.section h2{
  font-size:clamp(28px,4vw,44px); text-transform:uppercase; letter-spacing:.01em;
}
.section .lede{ color:var(--muted); max-width:620px; margin-top:18px; font-size:18px; }

/* ---------- buttons ---------- */
.btn{
  display:inline-flex; align-items:center; gap:10px;
  font-weight:700; font-size:15px; letter-spacing:.02em;
  padding:15px 28px; border-radius:var(--radius);
  border:1px solid transparent; cursor:pointer;
  transition:transform .18s var(--ease), background .18s, border-color .18s;
  white-space:nowrap;
}
.btn:active{ transform:translateY(1px); }
.btn-primary{ background:var(--red); color:#fff; }
.btn-primary:hover{ background:var(--red-deep); }
.btn-ghost{ background:transparent; color:var(--text); border-color:var(--line-2); }
.btn-ghost:hover{ border-color:var(--text); }
.btn-block{ width:100%; justify-content:center; }
.btn .arrow{ transition:transform .18s var(--ease); }
.btn:hover .arrow{ transform:translateX(4px); }

/* ---------- header ---------- */
.site-header{
  position:sticky; top:0; z-index:60;
  background:rgba(10,10,12,.78);
  backdrop-filter:saturate(140%) blur(12px);
  border-bottom:1px solid var(--line);
}
.nav{ display:flex; align-items:center; justify-content:space-between; height:72px; }
.brand{ display:flex; align-items:center; gap:12px; }
.brand img{ height:38px; width:auto; }
.brand .brand-name{ font-weight:800; letter-spacing:.16em; font-size:15px; text-transform:uppercase; }
.brand .brand-name small{ display:block; font-size:9.5px; letter-spacing:.34em; color:var(--muted-2); font-weight:600; }
.nav-links{ display:flex; align-items:center; gap:34px; list-style:none; }
.nav-links a{
  font-size:14.5px; font-weight:600; color:var(--muted); letter-spacing:.03em;
  transition:color .15s; position:relative;
}
.nav-links a:hover,.nav-links a.active{ color:var(--text); }
.nav-links a.active::after{
  content:""; position:absolute; left:0; right:0; bottom:-26px; height:2px; background:var(--red);
}
.nav-cta{ display:flex; align-items:center; gap:14px; }
.nav-toggle{ display:none; background:none; border:0; color:var(--text); cursor:pointer; padding:8px; }
.nav-toggle span{ display:block; width:24px; height:2px; background:currentColor; margin:5px 0; transition:.25s; }

/* ---------- hero ---------- */
.hero{ position:relative; min-height:88vh; display:flex; align-items:center; overflow:hidden; }
.hero::before{
  content:""; position:absolute; inset:0;
  background:linear-gradient(100deg, var(--bg) 30%, rgba(10,10,12,.55) 62%, rgba(10,10,12,.2) 100%),
             url("../assets/hero-engine.jpg") center right/cover no-repeat;
  z-index:0;
}
.hero::after{
  content:""; position:absolute; inset:0; z-index:1;
  background:radial-gradient(120% 80% at 0% 50%, rgba(230,38,25,.10), transparent 55%);
}
.hero .wrap{ position:relative; z-index:2; padding-top:60px; padding-bottom:60px; }
.hero h1{
  font-size:clamp(44px,7.5vw,92px); text-transform:uppercase; letter-spacing:-.02em;
  line-height:.95; max-width:14ch;
}
.hero h1 .red{ color:var(--red); }
.hero p{ margin-top:26px; font-size:clamp(17px,2vw,21px); color:var(--muted); max-width:48ch; }
.hero .hero-cta{ margin-top:40px; display:flex; gap:16px; flex-wrap:wrap; }
.hero .specbar{
  margin-top:54px; display:flex; gap:40px; flex-wrap:wrap;
  border-top:1px solid var(--line); padding-top:26px; max-width:680px;
}
.hero .specbar div{ }
.hero .specbar b{ display:block; font-size:26px; font-weight:800; }
.hero .specbar span{ font-size:12.5px; color:var(--muted-2); letter-spacing:.08em; text-transform:uppercase; }

/* ---------- trust strip ---------- */
.trust{ border-top:1px solid var(--line); border-bottom:1px solid var(--line); background:var(--bg-2); }
.trust .wrap{ display:grid; grid-template-columns:repeat(4,1fr); }
.trust .item{ padding:30px 24px; border-right:1px solid var(--line); }
.trust .item:last-child{ border-right:0; }
.trust .item b{ display:block; font-size:15px; letter-spacing:.02em; }
.trust .item span{ font-size:13.5px; color:var(--muted); }

/* ---------- series grid ---------- */
.grid{ display:grid; gap:22px; margin-top:52px; }
.grid-3{ grid-template-columns:repeat(3,1fr); }
.grid-2{ grid-template-columns:repeat(2,1fr); }

.card{
  background:var(--surface); border:1px solid var(--line); border-radius:var(--radius);
  overflow:hidden; display:flex; flex-direction:column;
  transition:border-color .2s, transform .2s var(--ease);
}
.card:hover{ border-color:var(--line-2); transform:translateY(-3px); }
.card .thumb{ aspect-ratio:4/3; background:var(--bg-2) center/cover; position:relative; }
.card .thumb img{ width:100%; height:100%; object-fit:cover; }
.card .tag{
  position:absolute; top:14px; left:14px; z-index:2;
  font-size:11px; font-weight:700; letter-spacing:.1em; text-transform:uppercase;
  background:rgba(10,10,12,.82); color:var(--text); padding:6px 11px; border-radius:4px;
  border:1px solid var(--line-2);
}
.card .body{ padding:24px; display:flex; flex-direction:column; gap:10px; flex:1; }
.card .body h3{ font-size:21px; text-transform:uppercase; letter-spacing:.01em; }
.card .body p{ color:var(--muted); font-size:15px; }
.card .specs{ list-style:none; display:flex; flex-wrap:wrap; gap:8px; margin-top:2px; }
.card .specs li{ font-size:12px; color:var(--muted); background:var(--bg-2); border:1px solid var(--line); padding:4px 9px; border-radius:4px; }
.card .body .foot{ margin-top:auto; padding-top:14px; display:flex; align-items:center; justify-content:space-between; }
.card .body .foot .sku{ font-size:12.5px; color:var(--muted-2); letter-spacing:.05em; }
.card .body .foot a{ font-size:14px; font-weight:700; color:var(--red); display:inline-flex; align-items:center; gap:6px; }
.card .body .foot a:hover{ color:#fff; }

/* ---------- feature split ---------- */
.split{ display:grid; grid-template-columns:1fr 1fr; gap:64px; align-items:center; }
.split.reverse .split-media{ order:2; }
.split-media{ border-radius:var(--radius); overflow:hidden; border:1px solid var(--line); }
.split-media img{ width:100%; aspect-ratio:1/1; object-fit:cover; }
.split-body h2{ font-size:clamp(26px,3.5vw,38px); text-transform:uppercase; }
.split-body p{ color:var(--muted); margin-top:18px; }
.feature-list{ list-style:none; margin-top:26px; display:flex; flex-direction:column; gap:14px; }
.feature-list li{ display:flex; gap:14px; align-items:flex-start; font-size:15.5px; }
.feature-list li::before{
  content:""; flex:0 0 8px; width:8px; height:8px; margin-top:8px; border-radius:50%;
  background:var(--red); box-shadow:0 0 0 4px var(--red-soft);
}
.feature-list li b{ color:var(--text); }

/* ---------- spec table ---------- */
.spectable{ margin-top:40px; border:1px solid var(--line); border-radius:var(--radius); overflow:hidden; }
.spectable .row{ display:grid; grid-template-columns:1fr 1fr; border-bottom:1px solid var(--line); }
.spectable .row:last-child{ border-bottom:0; }
.spectable .row > div{ padding:16px 22px; }
.spectable .row > div:first-child{ color:var(--muted); border-right:1px solid var(--line); font-size:14.5px; letter-spacing:.04em; text-transform:uppercase; }
.spectable .row > div:last-child{ font-weight:600; }

/* ---------- CTA band ---------- */
.cta-band{ position:relative; overflow:hidden; border-top:1px solid var(--line); }
.cta-band::before{
  content:""; position:absolute; inset:0; z-index:0;
  background:linear-gradient(90deg, var(--bg) 35%, rgba(10,10,12,.4)),
             url("../assets/engine2.jpg") center/cover no-repeat; opacity:.9;
}
.cta-band.cta-blue::before{
  background:linear-gradient(90deg, var(--bg) 35%, rgba(10,10,12,.4)),
             url("../assets/engine-blue.jpg") center/cover no-repeat;
}
.cta-band .wrap{ position:relative; z-index:1; padding:88px 24px; text-align:left; }
.cta-band h2{ font-size:clamp(28px,4vw,46px); text-transform:uppercase; max-width:18ch; }
.cta-band p{ color:var(--muted); margin-top:16px; max-width:46ch; }
.cta-band .hero-cta{ margin-top:32px; display:flex; gap:16px; flex-wrap:wrap; }

/* ---------- page header (subpages) ---------- */
.page-head{ border-bottom:1px solid var(--line); background:var(--bg-2); padding:72px 0 64px; }
.page-head h1{ font-size:clamp(34px,5vw,60px); text-transform:uppercase; }
.page-head p{ color:var(--muted); margin-top:18px; max-width:60ch; font-size:18px; }

/* ---------- wholesale / form ---------- */
.form-grid{ display:grid; grid-template-columns:1.05fr .95fr; gap:64px; align-items:start; }
.rfq{ background:var(--surface); border:1px solid var(--line); border-radius:var(--radius); padding:36px; }
.field{ margin-bottom:20px; }
.field label{ display:block; font-size:13px; font-weight:600; letter-spacing:.06em; text-transform:uppercase; color:var(--muted); margin-bottom:9px; }
.field label .req{ color:var(--red); }
.field input,.field select,.field textarea{
  width:100%; background:var(--bg-2); border:1px solid var(--line-2); border-radius:5px;
  color:var(--text); font:inherit; font-size:15px; padding:13px 15px; transition:border-color .15s;
}
.field input:focus,.field select:focus,.field textarea:focus{ outline:none; border-color:var(--red); }
.field textarea{ resize:vertical; min-height:120px; }
.field-row{ display:grid; grid-template-columns:1fr 1fr; gap:18px; }
.checks{ display:grid; grid-template-columns:1fr 1fr; gap:10px; }
.check{ display:flex; align-items:center; gap:9px; font-size:14.5px; color:var(--text); background:var(--bg-2); border:1px solid var(--line); border-radius:5px; padding:11px 13px; cursor:pointer; }
.check input{ width:auto; accent-color:var(--red); }
.form-note{ font-size:13px; color:var(--muted-2); margin-top:6px; }
.form-status{ display:none; margin-top:16px; padding:14px 16px; border-radius:5px; font-size:14.5px; }
.form-status.ok{ display:block; background:var(--red-soft); border:1px solid var(--red); color:#fff; }

.contact-block{ display:flex; flex-direction:column; gap:24px; }
.contact-item{ border-left:2px solid var(--red); padding-left:18px; }
.contact-item span{ font-size:12.5px; letter-spacing:.1em; text-transform:uppercase; color:var(--muted-2); display:block; margin-bottom:5px; }
.contact-item b{ font-size:17px; font-weight:700; }
.contact-item a{ color:var(--text); }
.contact-item a:hover{ color:var(--red); }
.why-list{ list-style:none; display:flex; flex-direction:column; gap:16px; margin-top:8px; }
.why-list li{ display:flex; gap:13px; font-size:15.5px; color:var(--muted); }
.why-list li b{ color:var(--text); }
.why-list li::before{ content:"—"; color:var(--red); font-weight:800; }

/* ---------- about ---------- */
.prose{ max-width:720px; }
.prose p{ color:var(--muted); margin-bottom:22px; font-size:17.5px; }
.prose p strong{ color:var(--text); }
.stat-row{ display:grid; grid-template-columns:repeat(3,1fr); gap:22px; margin:48px 0; }
.stat{ border:1px solid var(--line); border-radius:var(--radius); padding:28px; background:var(--surface); }
.stat b{ font-size:38px; font-weight:800; display:block; }
.stat span{ color:var(--muted); font-size:14px; }

/* ---------- footer ---------- */
.site-footer{ border-top:1px solid var(--line); background:var(--bg-2); padding:64px 0 36px; }
.footer-top{ display:grid; grid-template-columns:1.4fr 1fr 1fr 1fr; gap:40px; }
.footer-brand img{ height:40px; margin-bottom:18px; }
.footer-brand p{ color:var(--muted); font-size:14.5px; max-width:30ch; }
.footer-col h4{ font-size:12.5px; letter-spacing:.14em; text-transform:uppercase; color:var(--muted-2); margin-bottom:16px; }
.footer-col ul{ list-style:none; display:flex; flex-direction:column; gap:11px; }
.footer-col a{ color:var(--muted); font-size:14.5px; }
.footer-col a:hover{ color:var(--text); }
.footer-bottom{ margin-top:52px; padding-top:26px; border-top:1px solid var(--line); display:flex; justify-content:space-between; gap:18px; flex-wrap:wrap; }
.footer-bottom p{ color:var(--muted-2); font-size:13px; }

/* ---------- reveal on scroll (progressive enhancement: only hides when JS is on) ---------- */
.js .reveal{ opacity:0; transform:translateY(22px); transition:opacity .7s var(--ease), transform .7s var(--ease); }
.js .reveal.in{ opacity:1; transform:none; }
@media (prefers-reduced-motion:reduce){
  .js .reveal{ opacity:1 !important; transform:none !important; }
}

/* ---------- responsive ---------- */
@media (max-width:960px){
  .split,.form-grid{ grid-template-columns:1fr; gap:36px; }
  .split.reverse .split-media{ order:0; }
  .footer-top{ grid-template-columns:1fr 1fr; gap:32px; }
  .grid-3{ grid-template-columns:repeat(2,1fr); }
}
@media (max-width:720px){
  body{ font-size:16px; }
  .section{ padding:64px 0; }
  .nav-links,.nav-cta .btn{ display:none; }
  .nav-toggle{ display:block; }
  .site-header.open .nav-links{
    display:flex; position:absolute; top:72px; left:0; right:0; flex-direction:column;
    gap:0; background:var(--bg-2); border-bottom:1px solid var(--line); padding:8px 0;
  }
  .site-header.open .nav-links a{ padding:15px 24px; width:100%; font-size:16px; color:var(--text); }
  .site-header.open .nav-links a.active::after{ display:none; }
  .trust .wrap{ grid-template-columns:1fr 1fr; }
  .trust .item:nth-child(2){ border-right:0; }
  .trust .item:nth-child(1),.trust .item:nth-child(2){ border-bottom:1px solid var(--line); }
  .grid-3,.grid-2,.stat-row,.checks,.field-row{ grid-template-columns:1fr; }
  .hero .specbar{ gap:26px; }
  .hero .specbar b{ font-size:22px; }
  .spectable .row{ grid-template-columns:1fr; }
  .spectable .row > div:first-child{ border-right:0; border-bottom:1px solid var(--line); }
}