/* ===== BISS-C 云平台 首页样式 =====
   风格与固件 Web 界面一致：深色背景 + 青绿 #4ecca3 强调色 */
:root{
  --bg:#1a1a2e;
  --bg-alt:#16213e;
  --card:#16213e;
  --border:#2a3550;
  --accent:#4ecca3;
  --accent-dark:#45b090;
  --warn:#f9a826;
  --err:#e94560;
  --text:#eee;
  --muted:#9aa3b2;
  --dim:#888;
}
*{box-sizing:border-box;margin:0;padding:0;}
html{scroll-behavior:smooth;}
body{
  font-family:Arial,'PingFang SC','Microsoft YaHei',sans-serif;
  background:var(--bg);color:var(--text);line-height:1.6;
  -webkit-font-smoothing:antialiased;
}
img{max-width:100%;display:block;}
a{color:var(--accent);text-decoration:none;}
.container{max-width:1080px;margin:0 auto;padding:0 20px;}
.muted{color:var(--muted);}
.small{font-size:.85em;}
.val{font-family:monospace;color:var(--warn);}

/* ===== 导航 ===== */
.topbar{
  position:sticky;top:0;z-index:100;
  background:rgba(22,33,62,.92);backdrop-filter:blur(8px);
  border-bottom:1px solid var(--border);
}
.topbar-inner{display:flex;align-items:center;justify-content:space-between;height:60px;}
.brand{display:flex;align-items:center;gap:8px;}
.brand-dot{width:12px;height:12px;border-radius:50%;background:var(--accent);
  box-shadow:0 0 10px var(--accent);}
.brand-name{font-weight:bold;font-size:1.05em;color:var(--text);}
.brand-sub{font-size:.72em;color:var(--dim);font-family:monospace;}
.nav{display:flex;align-items:center;gap:18px;}
.nav a{color:var(--muted);font-size:.9em;transition:color .2s;}
.nav a:hover{color:var(--accent);}
.nav .nav-cta{
  color:var(--accent);border:2px solid var(--accent);
  border-radius:20px;padding:6px 16px;font-weight:bold;
}
.nav .nav-cta:hover{background:var(--accent);color:var(--bg);}
.nav-toggle{display:none;background:none;border:none;color:var(--text);font-size:1.4em;cursor:pointer;}

/* ===== Hero ===== */
.hero{
  padding:70px 0 60px;
  background:radial-gradient(900px 420px at 85% -10%,rgba(78,204,163,.12),transparent 60%),
             radial-gradient(700px 400px at -10% 110%,rgba(78,204,163,.08),transparent 60%);
  border-bottom:1px solid var(--border);
}
.hero-grid{display:grid;grid-template-columns:1.1fr 1fr;gap:40px;align-items:center;}
.hero-badge{
  display:inline-block;font-size:.78em;color:var(--accent);
  border:1px solid var(--accent);border-radius:20px;padding:4px 14px;margin-bottom:16px;
  background:rgba(78,204,163,.08);
}
.hero h1{
  font-size:2.5em;line-height:1.2;margin-bottom:14px;
  background:linear-gradient(90deg,#fff,var(--accent));
  -webkit-background-clip:text;background-clip:text;-webkit-text-fill-color:transparent;
}
.hero-sub{color:var(--muted);font-size:1.05em;margin-bottom:24px;max-width:520px;}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:28px;}
.btn{
  display:inline-block;padding:10px 26px;border-radius:24px;
  font-weight:bold;font-size:.95em;border:1px solid transparent;cursor:pointer;
  transition:all .2s;
}
.btn-primary{background:var(--accent);color:var(--bg);}
.btn-primary:hover{background:var(--accent-dark);transform:translateY(-1px);}
.btn-ghost{color:var(--accent);border-color:var(--accent);}
.btn-ghost:hover{background:rgba(78,204,163,.12);}
.btn-outline{color:var(--accent);border-color:var(--border);}
.btn-outline:hover{border-color:var(--accent);}
.hero-metrics{display:flex;gap:30px;flex-wrap:wrap;}
.metric{display:flex;flex-direction:column;}
.m-val{font-size:1.4em;font-weight:bold;color:var(--accent);font-family:monospace;}
.m-lbl{font-size:.78em;color:var(--dim);}
.hero-visual{
  border:1px solid var(--border);border-radius:16px;overflow:hidden;
  box-shadow:0 20px 60px rgba(0,0,0,.45);
}
.hero-visual img{width:100%;height:auto;aspect-ratio:16/9;object-fit:cover;}

/* ===== Section ===== */
.section{padding:64px 0;}
.section.alt{background:var(--bg-alt);border-top:1px solid var(--border);border-bottom:1px solid var(--border);}
.section-head{text-align:center;margin-bottom:40px;}
.section-head h2{font-size:1.8em;color:var(--accent);margin-bottom:8px;}
.section-head p{color:var(--muted);}

/* ===== 特性卡片 ===== */
.grid{display:grid;gap:16px;}
.features{grid-template-columns:repeat(4,1fr);}
@media(max-width:900px){.features{grid-template-columns:repeat(2,1fr);}}
@media(max-width:560px){.features{grid-template-columns:1fr;}}
.card{
  background:var(--card);border:1px solid var(--border);border-radius:12px;
  padding:20px;transition:transform .15s,border-color .2s;
}
.card:hover{transform:translateY(-3px);border-color:var(--accent);}
.card-ico{font-size:1.7em;margin-bottom:10px;}
.card h3{color:var(--accent);font-size:1.05em;margin-bottom:8px;}
.card p{color:var(--muted);font-size:.9em;}

/* ===== 数据链路 ===== */
.pipeline{display:flex;align-items:stretch;gap:16px;}
.pipe-step{
  flex:1;background:var(--card);border:1px solid var(--border);border-radius:12px;
  padding:22px;text-align:center;position:relative;
}
.pipe-num{
  width:36px;height:36px;line-height:36px;margin:0 auto 12px;border-radius:50%;
  background:var(--accent);color:var(--bg);font-weight:bold;font-size:1.05em;
}
.pipe-title{font-weight:bold;color:var(--text);margin-bottom:8px;}
.pipe-step p{color:var(--muted);font-size:.88em;}
.pipe-arrow{align-self:center;color:var(--accent);font-size:1.6em;flex:none;}
@media(max-width:760px){.pipeline{flex-direction:column;}.pipe-arrow{transform:rotate(90deg);align-self:center;}}

/* ===== 价格 ===== */
.pricing{grid-template-columns:repeat(2,1fr);margin:0 auto;}
@media(max-width:600px){.pricing{grid-template-columns:1fr;}}
.price-card{position:relative;text-align:center;padding:30px 24px;}
.price-card.pro{border-color:var(--accent);box-shadow:0 0 0 1px var(--accent),0 12px 40px rgba(78,204,163,.12);}
.price-tag{
  position:absolute;top:-12px;left:50%;transform:translateX(-50%);
  background:var(--accent);color:var(--bg);font-size:.78em;font-weight:bold;
  padding:3px 16px;border-radius:12px;
}
.price-name{color:var(--dim);font-size:.95em;margin-bottom:6px;}
.price-val{font-size:2em;font-weight:bold;color:var(--text);margin-bottom:18px;}
.price-unit{font-size:.5em;color:var(--dim);font-weight:normal;margin-left:4px;}
.price-feats{list-style:none;text-align:left;margin-bottom:22px;min-height:290px;}
.price-feats li{padding:7px 0;border-bottom:1px dashed var(--border);font-size:.9em;color:var(--muted);}
.price-feats li.ok{color:var(--text);}
.price-feats li.no{color:var(--dim);}

/* ===== 步骤 ===== */
.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;}
@media(max-width:760px){.steps{grid-template-columns:1fr;}}
.step{
  background:var(--card);border:1px solid var(--border);border-radius:12px;padding:22px;
  border-top:3px solid var(--accent);
}
.step-num{font-size:1.6em;font-weight:bold;color:var(--accent);opacity:.5;font-family:monospace;}
.step h3{color:var(--text);margin:6px 0 8px;font-size:1.05em;}
.step p{color:var(--muted);font-size:.9em;}
.step code{
  background:rgba(78,204,163,.1);color:var(--accent);
  border:1px solid var(--border);border-radius:4px;padding:1px 6px;font-size:.85em;
}

/* ===== 协议表 ===== */
.proto-cols{display:grid;grid-template-columns:1fr 1fr;gap:16px;}
@media(max-width:760px){.proto-cols{grid-template-columns:1fr;}}
.proto-card h3{color:var(--accent);margin-bottom:12px;font-size:1.05em;}
table.proto{border-collapse:collapse;width:100%;font-size:.85em;}
table.proto th,table.proto td{
  border:1px solid var(--border);padding:8px 10px;text-align:left;
}
table.proto th{background:var(--bg-alt);color:var(--accent);}
table.proto td{color:var(--muted);}
.note{
  margin-top:16px;padding:12px 16px;border:1px solid var(--border);border-left:3px solid var(--warn);
  background:rgba(249,168,38,.06);border-radius:6px;color:var(--muted);font-size:.88em;
}

/* ===== FAQ ===== */
.faq{max-width:820px;margin:0 auto;}
.faq details{
  background:var(--card);border:1px solid var(--border);border-radius:10px;
  margin-bottom:12px;padding:14px 18px;
}
.faq summary{
  cursor:pointer;font-weight:bold;color:var(--text);font-size:.98em;
  list-style:none;position:relative;padding-right:24px;
}
.faq summary::-webkit-details-marker{display:none;}
.faq summary::after{
  content:"+";position:absolute;right:0;top:0;color:var(--accent);font-size:1.2em;
}
.faq details[open] summary::after{content:"−";}
.faq p{color:var(--muted);font-size:.9em;margin-top:10px;}
.faq code{
  background:rgba(78,204,163,.1);color:var(--accent);
  border:1px solid var(--border);border-radius:4px;padding:1px 6px;font-size:.85em;
}

/* ===== Footer ===== */
.footer{border-top:1px solid var(--border);padding:36px 0;background:var(--bg-alt);}
.footer-inner{display:flex;justify-content:space-between;align-items:center;gap:16px;flex-wrap:wrap;}
.footer-links{display:flex;gap:18px;}
.footer-links a{color:var(--muted);font-size:.88em;}
.footer-links a:hover{color:var(--accent);}
.footer-beian{width:100%;display:flex;justify-content:center;align-items:center;flex-wrap:wrap;gap:10px 40px;padding:10px;}
.footer-beian a{color:#9aa3b2;display:inline-flex;align-items:center;gap:6px;}
.footer-beian img{width:auto;height:15px;}

/* ===== 移动端导航 ===== */
@media(max-width:860px){
  .nav-toggle{display:block;}
  .nav{
    display:none;position:absolute;top:60px;left:0;right:0;
    background:var(--bg-alt);border-bottom:1px solid var(--border);
    flex-direction:column;align-items:stretch;padding:12px 20px 20px;gap:14px;
  }
  .nav.open{display:flex;}
  .nav .nav-cta{text-align:center;}
  .hero-grid{grid-template-columns:1fr;}
  .hero{padding:48px 0;}
  .hero h1{font-size:2em;}
}