:root{
  --bg:#0d1117;
  --bg-2:#131a23;
  --bg-3:#1a2330;
  --border:#25303f;
  --text:#e6edf3;
  --muted:#8b98a8;
  --accent:#00d4ff;
  --accent-2:#00ffa3;
  --danger:#ff5c7a;
  --shadow:0 8px 32px rgba(0,0,0,.45);
  --radius:14px;
}

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

html,body{
  background:var(--bg);
  color:var(--text);
  font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  line-height:1.65;
  font-size:16px;
  -webkit-font-smoothing:antialiased;
}

a{color:var(--accent);text-decoration:none;transition:.2s}
a:hover{color:var(--accent-2)}

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

.container{
  max-width:1200px;
  margin:0 auto;
  padding:0 24px;
}

header{
  position:sticky;
  top:0;
  z-index:100;
  background:rgba(13,17,23,.85);
  backdrop-filter:blur(14px);
  -webkit-backdrop-filter:blur(14px);
  border-bottom:1px solid var(--border);
}

.nav{
  display:flex;
  align-items:center;
  justify-content:space-between;
  height:74px;
}

.logo{
  font-weight:800;
  font-size:1rem;
  letter-spacing:.3px;
  color:var(--text);
  display:flex;
  align-items:center;
  gap:10px;
  line-height:1.15;
  max-width:230px;
}
.logo::before{
  content:"";
  flex-shrink:0;
  width:12px;height:12px;
  border-radius:50%;
  background:linear-gradient(135deg,var(--accent),var(--accent-2));
  box-shadow:0 0 12px var(--accent);
}

.nav-links{
  display:flex;
  gap:20px;
  list-style:none;
}
.nav-links a{
  color:var(--muted);
  font-size:.88rem;
  font-weight:500;
  position:relative;
  white-space:nowrap;
}
.nav-links a:hover, .nav-links a.active{color:var(--text)}
.nav-links a.active::after{
  content:"";
  position:absolute;
  left:0;right:0;bottom:-27px;
  height:2px;
  background:var(--accent);
  box-shadow:0 0 10px var(--accent);
}

.burger{
  display:none;
  background:none;border:none;
  cursor:pointer;
  padding:8px;
}
.burger span{
  display:block;width:24px;height:2px;
  background:var(--text);margin:5px 0;
  transition:.3s;
}

.hero{
  padding:100px 0 80px;
  text-align:center;
  position:relative;
  overflow:hidden;
}
.hero::before{
  content:"";
  position:absolute;
  top:-50%;left:50%;
  transform:translateX(-50%);
  width:900px;height:900px;
  background:radial-gradient(circle,rgba(0,212,255,.12),transparent 60%);
  pointer-events:none;
}
.hero h1{
  font-size:clamp(1.9rem,4.5vw,3.2rem);
  font-weight:800;
  letter-spacing:-1px;
  margin-bottom:20px;
  background:linear-gradient(135deg,#fff 30%,var(--accent));
  -webkit-background-clip:text;
  background-clip:text;
  -webkit-text-fill-color:transparent;
  position:relative;
}
.hero p{
  color:var(--muted);
  font-size:1.08rem;
  max-width:680px;
  margin:0 auto 34px;
  position:relative;
}

.hero-actions{
  display:flex;
  justify-content:center;
  gap:14px;
  flex-wrap:wrap;
  position:relative;
}

.btn{
  display:inline-block;
  padding:13px 30px;
  border-radius:10px;
  background:linear-gradient(135deg,var(--accent),var(--accent-2));
  color:#04121a !important;
  font-weight:700;
  transition:.25s;
  box-shadow:0 4px 20px rgba(0,212,255,.25);
  font-size:.95rem;
}
.btn:hover{transform:translateY(-2px);box-shadow:0 8px 30px rgba(0,212,255,.45)}
.btn.outline{
  background:transparent;
  color:var(--text) !important;
  border:1px solid var(--border);
  box-shadow:none;
}
.btn.outline:hover{border-color:var(--accent);color:var(--accent) !important}

section{padding:70px 0}
.section-title{
  font-size:clamp(1.5rem,3vw,2rem);
  font-weight:800;
  margin-bottom:12px;
  letter-spacing:-.5px;
}
.section-sub{
  color:var(--muted);
  margin-bottom:44px;
  max-width:720px;
}

.grid{
  display:grid;
  grid-template-columns:repeat(auto-fill,minmax(300px,1fr));
  gap:24px;
}

.card{
  background:linear-gradient(180deg,var(--bg-2),var(--bg-3));
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:28px;
  transition:.3s;
  position:relative;
  overflow:hidden;
  display:block;
}
.card:hover{
  transform:translateY(-4px);
  border-color:var(--accent);
  box-shadow:var(--shadow);
}
.card h3{
  font-size:1.12rem;
  margin-bottom:10px;
  color:var(--text);
}
.card p{color:var(--muted);font-size:.93rem}

.cable-card{
  background:linear-gradient(180deg,var(--bg-2),var(--bg-3));
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:28px;
  margin-bottom:32px;
  transition:.3s;
}
.cable-card:hover{border-color:var(--accent)}

.cable-head{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:18px;
  margin-bottom:20px;
}
.cable-head h2{
  font-size:1.5rem;
  letter-spacing:-.3px;
}
.badge{
  display:inline-block;
  padding:4px 12px;
  border-radius:20px;
  font-size:.72rem;
  font-weight:700;
  text-transform:uppercase;
  letter-spacing:.6px;
  background:rgba(0,212,255,.12);
  color:var(--accent);
  border:1px solid rgba(0,212,255,.3);
}

.cable-body{
  display:grid;
  grid-template-columns:340px 1fr;
  gap:32px;
  align-items:start;
}

.cable-visual{
  background:var(--bg);
  border:1px solid var(--border);
  border-radius:12px;
  padding:20px;
  display:flex;
  align-items:center;
  justify-content:center;
}

.specs{
  list-style:none;
  display:grid;
  grid-template-columns:repeat(auto-fill,minmax(220px,1fr));
  gap:10px 24px;
  margin-top:16px;
  font-size:.9rem;
}
.specs li{
  display:flex;
  justify-content:space-between;
  gap:12px;
  padding:8px 0;
  border-bottom:1px dashed var(--border);
}
.specs li span:first-child{color:var(--muted)}
.specs li span:last-child{color:var(--text);font-weight:600;text-align:right}

.calc-wrap{
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:32px;
}
.calc-form, .calc-result{
  background:linear-gradient(180deg,var(--bg-2),var(--bg-3));
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:32px;
}
.field{margin-bottom:20px}
.field label{
  display:block;
  margin-bottom:8px;
  font-size:.9rem;
  color:var(--muted);
  font-weight:500;
}
.field input, .field select{
  width:100%;
  padding:12px 14px;
  background:var(--bg);
  border:1px solid var(--border);
  border-radius:10px;
  color:var(--text);
  font-size:1rem;
  transition:.2s;
  font-family:inherit;
}
.field input:focus, .field select:focus{
  outline:none;
  border-color:var(--accent);
  box-shadow:0 0 0 3px rgba(0,212,255,.15);
}

.result-row{
  display:flex;
  justify-content:space-between;
  padding:14px 0;
  border-bottom:1px solid var(--border);
}
.result-row:last-child{border-bottom:none}
.result-row .label{color:var(--muted)}
.result-row .value{font-weight:700;color:var(--accent-2);font-size:1.1rem}

.result-big{
  text-align:center;
  padding:24px 0;
  border-bottom:1px solid var(--border);
  margin-bottom:16px;
}
.result-big .value{
  font-size:2.4rem;
  font-weight:800;
  color:var(--accent);
  display:block;
  letter-spacing:-1px;
}
.result-big .label{color:var(--muted);font-size:.85rem}

.article-full{
  max-width:800px;
  margin:0 auto;
}
.article-full h1{
  font-size:clamp(1.7rem,4vw,2.5rem);
  margin-bottom:12px;
  letter-spacing:-.5px;
}
.article-full .meta{
  color:var(--muted);
  font-size:.88rem;
  margin-bottom:36px;
  padding-bottom:20px;
  border-bottom:1px solid var(--border);
}
.article-full h2{
  font-size:1.4rem;
  margin:36px 0 14px;
  color:var(--accent);
}
.article-full p{margin-bottom:16px;color:#cdd7e0}
.article-full ul, .article-full ol{margin:0 0 16px 22px;color:#cdd7e0}
.article-full li{margin-bottom:8px}
.article-full blockquote{
  border-left:3px solid var(--accent);
  padding:8px 20px;
  background:var(--bg-2);
  border-radius:0 10px 10px 0;
  color:var(--muted);
  margin:20px 0;
  font-style:italic;
}

.steps{display:grid;gap:24px}
.step{
  display:grid;
  grid-template-columns:60px 1fr;
  gap:24px;
  background:linear-gradient(180deg,var(--bg-2),var(--bg-3));
  border:1px solid var(--border);
  border-radius:var(--radius);
  padding:26px;
  transition:.3s;
}
.step:hover{border-color:var(--accent)}
.step-num{
  width:52px;height:52px;
  border-radius:50%;
  background:linear-gradient(135deg,var(--accent),var(--accent-2));
  color:#04121a;
  font-weight:800;
  font-size:1.3rem;
  display:flex;
  align-items:center;
  justify-content:center;
  box-shadow:0 4px 16px rgba(0,212,255,.3);
}
.step h3{margin-bottom:8px;font-size:1.1rem}
.step p{color:var(--muted);font-size:.94rem}

footer{
  border-top:1px solid var(--border);
  padding:40px 0;
  margin-top:60px;
  text-align:center;
  color:var(--muted);
  font-size:.88rem;
}

@media(max-width:1100px){
  .nav-links{gap:14px}
  .nav-links a{font-size:.82rem}
  .logo{font-size:.9rem;max-width:200px}
}

@media(max-width:900px){
  .cable-body{grid-template-columns:1fr}
  .calc-wrap{grid-template-columns:1fr}
}

@media(max-width:720px){
  .nav-links{
    position:fixed;
    top:74px;left:0;right:0;
    background:var(--bg-2);
    flex-direction:column;
    gap:0;
    padding:16px 24px 24px;
    border-bottom:1px solid var(--border);
    transform:translateY(-120%);
    transition:.3s;
    max-height:calc(100vh - 74px);
    overflow-y:auto;
  }
  .nav-links.open{transform:translateY(0)}
  .nav-links a{padding:14px 0;border-bottom:1px solid var(--border);display:block;font-size:.95rem}
  .nav-links a.active::after{display:none}
  .burger{display:block}
  .burger.active span:nth-child(1){transform:rotate(45deg) translate(5px,5px)}
  .burger.active span:nth-child(2){opacity:0}
  .burger.active span:nth-child(3){transform:rotate(-45deg) translate(5px,-5px)}

  .hero{padding:60px 0 50px}
  section{padding:50px 0}
  .step{grid-template-columns:1fr;gap:14px}
  .card, .cable-card, .calc-form, .calc-result{padding:22px}
  .logo{font-size:.82rem;max-width:180px}
}