/* ===== Bauhaus · 包豪斯构成主义 · bh- ===== */
:root{
  --bh-bg:#f4f1ea;
  --bh-ink:#141414;
  --bh-red:#e63329;
  --bh-blue:#1a4fbf;
  --bh-yellow:#f5c518;
  --bh-surface:#ffffff;
  --bh-line:#141414;
  --bh-maxw:1140px;
  --bh-font:"Archivo Black","Arial Black","PingFang SC","Microsoft YaHei",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --bh-body:"PingFang SC","Microsoft YaHei","Hiragano Sans GB",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --bh-ease:cubic-bezier(.2,.8,.2,1);
}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--bh-body);background:var(--bh-bg);color:var(--bh-ink);line-height:1.7;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
.bh-wrap{max-width:var(--bh-maxw);margin:0 auto;padding:0 24px}

/* mark */
.bh-m-circle,.bh-m-tri,.bh-m-sq{display:inline-block;vertical-align:middle}
.bh-m-circle{width:14px;height:14px;border-radius:50%;background:var(--bh-red)}
.bh-m-tri{width:0;height:0;border-left:8px solid transparent;border-right:8px solid transparent;border-bottom:14px solid var(--bh-blue);margin:0 4px}
.bh-m-sq{width:14px;height:14px;background:var(--bh-yellow);border:2px solid var(--bh-ink)}

/* header */
.bh-head{position:sticky;top:0;z-index:50;background:var(--bh-bg);border-bottom:4px solid var(--bh-ink)}
.bh-bar{max-width:var(--bh-maxw);margin:0 auto;padding:13px 24px;display:flex;align-items:center;justify-content:space-between;gap:20px}
.bh-brand{display:flex;align-items:center;gap:10px;font-family:var(--bh-font);font-size:19px;letter-spacing:.5px}
.bh-brandtext em{font-family:var(--bh-body);font-style:normal;font-size:11px;font-weight:800;letter-spacing:1px;margin-left:8px;color:var(--bh-red)}
.bh-nav{display:flex;gap:28px;font-weight:800}
.bh-nav a{position:relative;padding:4px 0}
.bh-nav a::before{content:"";position:absolute;left:0;top:-4px;width:10px;height:10px;background:var(--bh-yellow);border:2px solid var(--bh-ink);transform:scale(0);transition:transform .2s var(--bh-ease)}
.bh-nav a:hover::before{transform:scale(1)}
.bh-burger{display:none;flex-direction:column;gap:5px;background:none;border:3px solid var(--bh-ink);padding:8px;cursor:pointer}
.bh-burger span{width:22px;height:3px;background:var(--bh-ink);display:block}

/* hero */
.bh-hero{padding:84px 0 70px;border-bottom:4px solid var(--bh-ink)}
.bh-hero-grid{max-width:var(--bh-maxw);margin:0 auto;padding:0 24px;display:grid;grid-template-columns:1.1fr .9fr;gap:48px;align-items:center}
.bh-kicker{display:inline-block;background:var(--bh-ink);color:var(--bh-yellow);font-weight:800;font-size:12px;letter-spacing:2px;padding:6px 14px}
.bh-h1{font-family:var(--bh-font);font-size:clamp(38px,6.4vw,70px);line-height:1.02;margin-top:18px;letter-spacing:-1px}
.bh-lead{margin-top:22px;font-size:clamp(15px,1.9vw,18px);max-width:560px}
.bh-cta{margin-top:32px;display:flex;gap:16px;flex-wrap:wrap}
.bh-btn{display:inline-flex;align-items:center;gap:8px;font-weight:800;border:3px solid var(--bh-ink);padding:13px 26px;transition:transform .2s var(--bh-ease)}
.bh-btn-red{background:var(--bh-red);color:#fff}
.bh-btn-red:hover{transform:translate(-3px,-3px);box-shadow:6px 6px 0 var(--bh-ink)}
.bh-btn-line{background:var(--bh-surface)}
.bh-btn-line:hover{background:var(--bh-yellow)}
.bh-arr{transition:transform .2s var(--bh-ease)}
.bh-btn:hover .bh-arr{transform:translateX(4px)}

/* compose art */
.bh-compose{position:relative;height:340px;border:4px solid var(--bh-ink);background:var(--bh-surface);overflow:hidden}
.bh-c{position:absolute;display:block}
.bh-c--circle{width:150px;height:150px;border-radius:50%;background:var(--bh-red);top:30px;left:30px}
.bh-c--square{width:120px;height:120px;background:var(--bh-yellow);border:4px solid var(--bh-ink);bottom:30px;right:30px}
.bh-c--tri{width:0;height:0;border-left:70px solid transparent;border-right:70px solid transparent;border-bottom:120px solid var(--bh-blue);top:40px;right:60px}
.bh-c--bar{width:100%;height:14px;background:var(--bh-ink);bottom:0;left:0}

/* sections */
.bh-sec{padding:70px 0}
.bh-sec-alt{background:var(--bh-ink);color:var(--bh-bg)}
.bh-sec-alt .bh-lead-c{color:#e9e6df}
.bh-head-row{display:flex;align-items:baseline;gap:14px;margin-bottom:20px;border-bottom:4px solid var(--bh-ink);padding-bottom:10px}
.bh-sec-alt .bh-head-row{border-color:var(--bh-yellow)}
.bh-no{font-family:var(--bh-font);font-size:16px;background:var(--bh-red);color:#fff;padding:4px 12px}
.bh-head-row h2{font-family:var(--bh-font);font-size:clamp(26px,4vw,38px);letter-spacing:-.5px}
.bh-lead-c{font-size:17px;max-width:720px;margin-bottom:30px}

/* cols2 */
.bh-cols2{display:grid;grid-template-columns:1fr 1fr;gap:24px}
.bh-block{background:var(--bh-surface);border:4px solid var(--bh-ink);padding:26px;transition:background .25s var(--bh-ease),color .25s var(--bh-ease)}
.bh-block h3{font-family:var(--bh-font);font-size:21px;margin-bottom:10px}
.bh-block p{font-size:15px}
.bh-block--blue{border-left:16px solid var(--bh-blue)}
.bh-block--yellow{border-left:16px solid var(--bh-yellow)}
.bh-block--red{border-left:16px solid var(--bh-red)}
.bh-block--ink{border-left:16px solid var(--bh-ink)}
.bh-sec .bh-block:hover{background:var(--bh-ink);color:var(--bh-bg)}
.bh-sec-alt .bh-block{background:transparent;color:var(--bh-bg)}
.bh-sec-alt .bh-block:hover{background:var(--bh-yellow);color:var(--bh-ink)}

/* list */
.bh-list{display:flex;flex-direction:column;gap:14px}
.bh-row{display:flex;align-items:center;gap:20px;border-bottom:3px solid var(--bh-yellow);padding:16px 0;transition:padding-left .2s var(--bh-ease)}
.bh-row:hover{padding-left:14px}
.bh-row p{font-size:15px;color:var(--bh-bg)}
.bh-tag{font-family:var(--bh-font);font-weight:800;color:#fff;padding:8px 16px;white-space:nowrap}
.bh-tag--red{background:var(--bh-red)}
.bh-tag--blue{background:var(--bh-blue)}
.bh-tag--yellow{background:var(--bh-yellow);color:var(--bh-ink)}

/* grid4 */
.bh-grid4{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}

/* steps */
.bh-steps{display:grid;grid-template-columns:repeat(4,1fr);gap:0;border:4px solid var(--bh-ink)}
.bh-step{padding:24px 20px;border-right:4px solid var(--bh-ink);position:relative}
.bh-step:last-child{border-right:none}
.bh-step-no{font-family:var(--bh-font);font-size:32px;color:var(--bh-red);display:block;line-height:1}
.bh-step b{font-family:var(--bh-font);font-size:18px;display:block;margin:8px 0 4px}
.bh-step span{font-size:14px}

/* faq */
.bh-faq{display:flex;flex-direction:column;gap:14px}
.bh-item{border:4px solid var(--bh-yellow);background:transparent}
.bh-item summary{list-style:none;cursor:pointer;padding:18px 22px;font-weight:800;font-size:17px;display:flex;justify-content:space-between;align-items:center}
.bh-item summary::-webkit-details-marker{display:none}
.bh-chev{font-style:normal;font-size:24px;font-weight:800;transition:transform .25s var(--bh-ease)}
.bh-item[open] .bh-chev{transform:rotate(45deg)}
.bh-item p{padding:0 22px 20px;font-size:15px;color:#e9e6df}

/* footer */
.bh-foot{border-top:4px solid var(--bh-ink);background:var(--bh-ink);color:var(--bh-bg)}
.bh-foot-in{display:flex;justify-content:space-between;align-items:center;padding:26px 24px;flex-wrap:wrap;gap:12px;font-weight:800}

/* top */
.bh-top{position:fixed;right:22px;bottom:22px;z-index:60;width:48px;height:48px;background:var(--bh-red);color:#fff;border:4px solid var(--bh-ink);display:flex;align-items:center;justify-content:center;font-size:22px;font-weight:800;opacity:0;pointer-events:none;transition:opacity .3s}
.bh-top.show{opacity:1;pointer-events:auto}

/* reveal */
.reveal{opacity:0;transform:translateY(24px);transition:opacity .6s var(--bh-ease),transform .6s var(--bh-ease)}
.reveal.in{opacity:1;transform:none}

@media(max-width:960px){
  .bh-hero-grid{grid-template-columns:1fr}
  .bh-compose{height:240px;order:-1}
  .bh-grid4{grid-template-columns:repeat(2,1fr)}
  .bh-steps{grid-template-columns:repeat(2,1fr)}
  .bh-step:nth-child(2){border-right:none}
  .bh-step:nth-child(1),.bh-step:nth-child(2){border-bottom:4px solid var(--bh-ink)}
}
@media(max-width:680px){
  .bh-nav{position:fixed;top:62px;right:0;flex-direction:column;background:var(--bh-bg);border:4px solid var(--bh-ink);padding:18px 26px;gap:16px;transform:translateX(120%);transition:transform .3s var(--bh-ease);z-index:49}
  .bh-nav.open{transform:none}
  .bh-burger{display:flex}
  .bh-grid4{grid-template-columns:1fr}
  .bh-steps{grid-template-columns:1fr}
  .bh-step{border-right:none;border-bottom:4px solid var(--bh-ink)}
  .bh-step:last-child{border-bottom:none}
  .bh-cols2{grid-template-columns:1fr}
  .bh-row{flex-direction:column;align-items:flex-start;gap:10px}
}
@media(prefers-reduced-motion:reduce){
  *{animation:none!important;transition:none!important}
  .reveal{opacity:1;transform:none}
}