/* style.css - Modern Tech Theme, Mobile First */
:root{--pri:#111827;--sec:#4f46e5;--cta:#0ea5e9;--cta-h:#0284c7;--txt:#374151;--mut:#6b7280;--bg:#fff;--bg-alt:#f9fafb;--bd:#e5e7eb;--surface:#fff;--shadow-sm:0 1px 2px 0 rgba(0,0,0,0.05);--shadow-md:0 4px 6px -1px rgba(0,0,0,0.1), 0 2px 4px -2px rgba(0,0,0,0.1);--radius-lg:0.75rem;--radius-xl:1rem;--font-sans:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;--fs-base:1rem;--fs-lg:1.125rem;--fs-xl:1.25rem;--fs-2xl:1.5rem;--fs-3xl:2.25rem;--fs-4xl:3rem;--lh-normal:1.65;--lh-tight:1.25;--gutter:1rem;--container:1140px;--speed:200ms}
*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{font-family:var(--font-sans);font-size:var(--fs-base);line-height:var(--lh-normal);color:var(--txt);background:var(--bg);-webkit-font-smoothing:antialiased}
img, svg{max-width:100%;height:auto;display:block}
a{color:var(--sec);text-decoration:none;font-weight:600;transition:color var(--speed)}
a:hover{color:var(--cta)}
.container{max-width:var(--container);margin:0 auto;padding:0 var(--gutter)}
section{padding:3.5rem 0}
h1,h2,h3{color:var(--pri);font-weight:700;line-height:var(--lh-tight)}
h1{font-size:var(--fs-3xl);letter-spacing:-.02em}
h2{font-size:var(--fs-2xl);text-align:center;margin-bottom:2.5rem}
h3{font-size:var(--fs-xl)}
.nav{position:sticky;top:0;z-index:10;background:rgba(255,255,255,.7);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);border-bottom:1px solid var(--bd)}
.nav .row{display:flex;justify-content:space-between;align-items:center;height:64px}
.logo{font-size:1.2rem;font-weight:700;color:var(--pri)}
.nav ul{display:none}
.hero{background:var(--bg-alt);padding:3.5rem 0;text-align:center}
.hero .subtitle{font-size:var(--fs-lg);color:var(--mut);max-width:65ch;margin:1rem auto 1.5rem}
.hero img{border-radius:var(--radius-xl);margin-top:2.5rem;box-shadow:var(--shadow-md)}
.cta, .btn-sub{display:inline-block;border-radius:var(--radius-lg);padding:0.75rem 1.5rem;font-weight:600;transition:all var(--speed);border:1px solid transparent}
.cta{background:var(--cta);color:#fff;border-color:var(--cta)}
.cta:hover{background:var(--cta-h);border-color:var(--cta-h);transform:translateY(-2px)}
.btns{display:flex;gap:0.75rem;flex-wrap:wrap;justify-content:center}
.btn-sub{background:transparent;color:var(--sec);border-color:var(--bd)}
.btn-sub:hover{background:var(--bg-alt);border-color:var(--sec)}
.grid-container{display:grid;gap:1.5rem}
.card{background:var(--surface);border:1px solid var(--bd);border-radius:var(--radius-xl);box-shadow:var(--shadow-sm);overflow:hidden;transition:all var(--speed)}
.card:hover{transform:translateY(-4px);box-shadow:var(--shadow-md)}
.card img{width:100%;height:220px;object-fit:cover}
.card-b{padding:1.5rem}
.advantages-grid{display:grid;gap:1.5rem}
.advantage{background:var(--bg-alt);padding:1.5rem;border-radius:var(--radius-xl);display:flex;gap:1rem;align-items:center}
.advantage .icon{flex-shrink:0;width:48px;height:48px;background:var(--cta);color:#fff;border-radius:var(--radius-lg);display:flex;align-items:center;justify-content:center}
.advantage h3{font-size:var(--fs-lg)}
.steps-grid{display:grid;gap:2.5rem;text-align:center;counter-reset:step-counter}
.step{background:var(--surface);border-top:4px solid var(--cta);border-radius:var(--radius-xl);padding:2rem 1.5rem;box-shadow:var(--shadow-md);position:relative}
.step::before{counter-increment:step-counter;content:"0" counter(step-counter);position:absolute;top:-1.25rem;left:50%;transform:translateX(-50%);background:var(--cta);color:#fff;width:2.5rem;height:2.5rem;border-radius:50%;display:flex;align-items:center;justify-content:center;font-weight:700}
.kb-layout{display:grid;gap:2rem}
#kb-nav{border-bottom:1px solid var(--bd);padding-bottom:1rem}
#kb-nav ul{display:flex;flex-wrap:wrap;list-style:none;gap:0.5rem}
#kb-nav a{display:block;padding:0.5rem 1rem;border-radius:var(--radius-lg);font-weight:600;background:var(--bg-alt)}
#kb-nav a:hover{background:var(--cta);color:var(--w)}
.kb-category{margin-bottom:3rem}
.kb-category h3{font-size:var(--fs-xl);text-align:left;padding-bottom:0.5rem;border-bottom:2px solid var(--bd);margin-bottom:1.5rem}
.kb-category details{border-bottom:1px solid var(--bd);padding:1rem 0}
.kb-category summary{cursor:pointer;font-weight:600;list-style:none;font-size:var(--fs-base)}
.kb-category summary::-webkit-details-marker{display:none}
.faq-answer{padding:0.75rem 0 0 1rem;color:var(--mut);line-height:1.8}
.faq-answer p, .faq-answer ul{margin-bottom:1rem}
.faq-answer ul{padding-left:1.25rem}
footer{background:var(--pri);color:rgba(255,255,255,0.7);text-align:center;padding:2.5rem var(--gutter)}
footer p{margin:0.5rem 0}
footer a{color:var(--cta)}
@media(min-width: 640px){.advantages-grid{grid-template-columns:repeat(2,1fr)}}
@media(min-width: 768px){
  :root{--gutter:2rem}
  h1{font-size:var(--fs-4xl)}
  .hero{text-align:left}
  .hero .wrap{display:grid;grid-template-columns:1fr 1fr;gap:2rem;align-items:center;text-align:left}
  .hero .subtitle{margin:1rem 0 2rem}
  .hero img{margin-top:0}
  .btns{justify-content:flex-start}
  .grid-container{grid-template-columns:repeat(3,1fr)}
  .steps-grid{grid-template-columns:repeat(3,1fr)}
}
@media(min-width: 1024px){
  .nav ul{display:flex;list-style:none;gap:2rem}
  .kb-layout{grid-template-columns:260px 1fr;gap:3rem}
  #kb-nav{border:none;padding:0;position:sticky;top:80px}
  #kb-nav ul{flex-direction:column}
  #kb-nav a{border-left:3px solid transparent}
  #kb-nav a:hover{background:var(--bg-alt);color:var(--cta);border-left-color:var(--cta)}
  .kb-category{scroll-margin-top:80px}
}