:root{
  --bg:#0e1116; --panel:#161b22; --line:#232a34; --fg:#e6edf3; --mut:#8b949e;
  --pri:#2f81f7; --pri-d:#1f6feb; --ok:#3fb950; --radius:12px;
  --maxw:1080px;
}
*{box-sizing:border-box}
html,body{margin:0;padding:0}
body{background:var(--bg);color:var(--fg);font:16px/1.6 -apple-system,"Segoe UI",system-ui,"Microsoft YaHei",sans-serif}
a{color:inherit;text-decoration:none}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 20px}

.nav{position:sticky;top:0;z-index:20;background:rgba(14,17,22,.8);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.nav-in{display:flex;align-items:center;justify-content:space-between;height:60px}
.brand{font-size:22px;font-weight:800;letter-spacing:-.5px}
.brand span{color:var(--pri)}
.nav nav{display:flex;align-items:center;gap:22px}
.nav nav a{color:var(--mut);font-size:15px}
.nav nav a:hover{color:var(--fg)}

.btn{display:inline-block;padding:10px 18px;border-radius:10px;font-weight:600;font-size:15px;cursor:pointer;border:1px solid transparent;transition:.15s}
.btn-primary{background:var(--pri);color:#fff}
.btn-primary:hover{background:var(--pri-d)}
.btn-ghost{border-color:var(--line);color:var(--fg)!important;background:transparent}
.btn-ghost:hover{border-color:var(--pri)}

.hero{padding:80px 0 60px;position:relative;overflow:hidden}
.hero-in{position:relative}
.hero h1{font-size:52px;line-height:1.1;margin:0 0 20px;letter-spacing:-1px;font-weight:800}
.hero .lead{font-size:19px;color:var(--mut);max-width:620px;margin:0 0 32px}
.cta{display:flex;gap:14px;flex-wrap:wrap;margin-bottom:50px}
.hero-card{background:var(--panel);border:1px solid var(--line);border-radius:16px;overflow:hidden;box-shadow:0 20px 60px rgba(0,0,0,.4);max-width:760px}
.hero-card .dots{display:flex;gap:7px;padding:12px 14px;border-bottom:1px solid var(--line)}
.hero-card .dots i{width:11px;height:11px;border-radius:50%;background:#333}
.hero-card .dots i:nth-child(1){background:#ff5f56}
.hero-card .dots i:nth-child(2){background:#ffbd2e}
.hero-card .dots i:nth-child(3){background:#27c93f}
.hero-card .screen{height:300px;display:flex;align-items:center;justify-content:center;color:var(--mut);
  background:repeating-linear-gradient(45deg,#12161c,#12161c 12px,#141a21 12px,#141a21 24px)}
.hero-card .connection-preview{height:auto;min-height:260px;gap:20px;padding:36px 24px;flex-wrap:wrap}
.connection-node{background:var(--panel);border:1px solid var(--line);padding:24px 20px;border-radius:12px;flex:1;min-width:220px}
.connection-node strong{display:block;color:var(--fg);font-size:19px;margin-bottom:8px}
.connection-node span{font-size:14px}
.connection-arrow{color:var(--pri);font-size:30px}
.connection-preview p{flex-basis:100%;text-align:center;font-size:14px;margin:0}

.section{padding:70px 0}
.section.alt{background:var(--panel);border-top:1px solid var(--line);border-bottom:1px solid var(--line)}
.section h2{font-size:32px;margin:0 0 36px;text-align:center;font-weight:800}
.grid{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.feat{background:var(--panel);border:1px solid var(--line);border-radius:var(--radius);padding:26px}
.section.alt .feat{background:var(--bg)}
.feat .ic{font-size:28px;margin-bottom:12px}
.feat h3{margin:0 0 8px;font-size:18px}
.feat p{margin:0;color:var(--mut);font-size:15px}

.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}
.step{display:flex;gap:14px;align-items:flex-start}
.step span{flex:0 0 36px;height:36px;border-radius:50%;background:var(--pri);color:#fff;display:flex;align-items:center;justify-content:center;font-weight:700}
.step p{margin:0;color:var(--mut)}

.foot{border-top:1px solid var(--line);padding:30px 0;color:var(--mut)}
.foot-in{display:flex;justify-content:space-between;font-size:14px}

/* auth + app pages */
.auth{min-height:calc(100vh - 60px);display:flex;align-items:center;justify-content:center;padding:40px 20px}
.card{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:34px;width:100%;max-width:400px}
.card h1{font-size:24px;margin:0 0 6px}
.card .sub{color:var(--mut);margin:0 0 26px;font-size:15px}
.field{margin-bottom:16px}
.field label{display:block;font-size:13px;color:var(--mut);margin-bottom:6px}
.input{width:100%;padding:12px 14px;background:var(--bg);border:1px solid var(--line);border-radius:10px;color:var(--fg);font-size:15px}
.input:focus{outline:none;border-color:var(--pri)}
.row{display:flex;gap:10px}
.row .input{flex:1}
.btn-block{width:100%;text-align:center;padding:12px}
.msg{font-size:14px;margin:12px 0 0;min-height:20px}
.msg.err{color:#f85149}
.msg.ok{color:var(--ok)}
.divider{display:flex;align-items:center;gap:12px;color:var(--mut);font-size:13px;margin:22px 0}
.divider::before,.divider::after{content:"";flex:1;height:1px;background:var(--line)}
.gbtn{display:flex;align-items:center;justify-content:center;gap:10px;width:100%;padding:11px;border:1px solid var(--line);border-radius:10px;background:#fff;color:#1f1f1f;font-weight:600}

.app-head{display:flex;align-items:center;justify-content:space-between;height:60px;border-bottom:1px solid var(--line)}
.dev-list{display:grid;grid-template-columns:repeat(auto-fill,minmax(260px,1fr));gap:16px;margin-top:24px}
.dev{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:18px}
.dev .id{font-size:22px;font-weight:700;letter-spacing:1px}
.dev .st{font-size:13px;margin:6px 0 14px}
.dev .st.on{color:var(--ok)}
.dev .st.off{color:var(--mut)}
.badge{display:inline-block;width:8px;height:8px;border-radius:50%;margin-right:6px;background:var(--mut)}
.badge.on{background:var(--ok)}

@media(max-width:820px){
  .hero h1{font-size:38px}
  .grid,.steps{grid-template-columns:1fr}
  .nav nav a:not(.btn){display:none}
}
@media(max-width:560px){.connection-preview{flex-direction:column}.connection-node{width:100%;min-width:0}.connection-arrow{transform:rotate(90deg)}}