/* ===== RESET & BASE ===== */
*,*::before,*::after{box-sizing:border-box;margin:0;padding:0}
:root{
  --bg:#0f172a;--surface:#1e293b;--card:#334155;
  --primary:#6366f1;--primary-light:#818cf8;--primary-dark:#4f46e5;
  --accent:#22d3ee;--accent2:#f472b6;--accent3:#a78bfa;
  --success:#34d399;--warning:#fbbf24;--danger:#f87171;
  --text:#f1f5f9;--text-muted:#94a3b8;--border:#475569;
  --radius:12px;--shadow:0 4px 24px rgba(0,0,0,.35);
  --font:'Segoe UI',system-ui,-apple-system,sans-serif;
}
html{scroll-behavior:smooth}
body{font-family:var(--font);background:var(--bg);color:var(--text);line-height:1.6;min-height:100vh}
a{color:var(--primary-light);text-decoration:none;transition:color .2s}
a:hover{color:var(--accent)}

/* ===== TOP NAV ===== */
.topnav{background:var(--surface);border-bottom:1px solid var(--border);padding:1rem 2rem;display:flex;align-items:center;justify-content:space-between;position:sticky;top:0;z-index:100;backdrop-filter:blur(12px)}
.topnav__brand{font-size:1.4rem;font-weight:700;color:var(--text);display:flex;align-items:center;gap:.5rem}
.topnav__brand span{font-size:1.6rem}
.topnav__links{display:flex;gap:1.5rem;align-items:center}
.topnav__links a{color:var(--text-muted);font-weight:500;padding:.4rem .8rem;border-radius:8px;transition:all .2s}
.topnav__links a:hover,.topnav__links a.active{color:var(--text);background:var(--card)}

/* ===== HERO ===== */
.hero{text-align:center;padding:4rem 2rem 3rem;background:linear-gradient(135deg,var(--surface) 0%,var(--bg) 100%)}
.hero h1{font-size:2.8rem;font-weight:800;margin-bottom:.5rem;background:linear-gradient(135deg,var(--primary-light),var(--accent));-webkit-background-clip:text;-webkit-text-fill-color:transparent;background-clip:text}
.hero p{font-size:1.15rem;color:var(--text-muted);max-width:600px;margin:0 auto}

/* ===== DOMAIN CARDS GRID ===== */
.domains-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:1.5rem;padding:2rem;max-width:1200px;margin:0 auto}
.domain-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.8rem;transition:all .3s;cursor:pointer;position:relative;overflow:hidden}
.domain-card::before{content:'';position:absolute;top:0;left:0;right:0;height:4px;background:linear-gradient(90deg,var(--primary),var(--accent));opacity:0;transition:opacity .3s}
.domain-card:hover{transform:translateY(-4px);box-shadow:var(--shadow);border-color:var(--primary)}
.domain-card:hover::before{opacity:1}
.domain-card__icon{font-size:2.5rem;margin-bottom:.8rem}
.domain-card__title{font-size:1.3rem;font-weight:700;margin-bottom:.4rem}
.domain-card__desc{color:var(--text-muted);font-size:.92rem;margin-bottom:1rem}
.domain-card__tools{display:flex;flex-wrap:wrap;gap:.4rem}
.domain-card__tag{background:var(--card);color:var(--text-muted);font-size:.75rem;padding:.25rem .6rem;border-radius:20px}

/* ===== PAGE HEADER ===== */
.page-header{padding:2.5rem 2rem 1.5rem;max-width:1100px;margin:0 auto}
.page-header__back{display:inline-flex;align-items:center;gap:.4rem;color:var(--text-muted);font-size:.9rem;margin-bottom:1rem;transition:color .2s}
.page-header__back:hover{color:var(--primary-light)}
.page-header h1{font-size:2.2rem;font-weight:800;margin-bottom:.3rem}
.page-header p{color:var(--text-muted);font-size:1rem}

/* ===== USE CASE BANNER ===== */
.use-case{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:1.2rem 1.5rem;margin:0 2rem 1.5rem;max-width:1068px;margin-left:auto;margin-right:auto}
.use-case__title{font-weight:700;font-size:.95rem;color:var(--accent);margin-bottom:.4rem}
.use-case__text{color:var(--text-muted);font-size:.88rem}

/* ===== ACCORDION ===== */
.accordion{max-width:1100px;margin:0 auto;padding:0 2rem 3rem;display:flex;flex-direction:column;gap:1rem}
.accordion-item{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);overflow:hidden;transition:border-color .3s}
.accordion-item.open{border-color:var(--primary)}
.accordion-header{display:flex;align-items:center;justify-content:space-between;padding:1.2rem 1.5rem;cursor:pointer;user-select:none;transition:background .2s}
.accordion-header:hover{background:rgba(99,102,241,.08)}
.accordion-header__left{display:flex;align-items:center;gap:.8rem}
.accordion-header__icon{font-size:1.4rem}
.accordion-header__title{font-weight:700;font-size:1.05rem}
.accordion-header__badge{font-size:.75rem;background:var(--primary);color:#fff;padding:.15rem .55rem;border-radius:20px}
.accordion-chevron{font-size:1.2rem;transition:transform .3s;color:var(--text-muted)}
.accordion-item.open .accordion-chevron{transform:rotate(180deg)}
.accordion-body{max-height:0;overflow:hidden;transition:max-height .4s ease}
.accordion-item.open .accordion-body{max-height:2000px}
.accordion-content{padding:0 1.5rem 1.5rem}

/* ===== CALCULATOR FORM ===== */
.calc-grid{display:grid;grid-template-columns:1fr 1fr;gap:1rem;margin-bottom:1.2rem}
.calc-grid.cols-3{grid-template-columns:1fr 1fr 1fr}
.calc-group{display:flex;flex-direction:column;gap:.3rem}
.calc-group label{font-size:.82rem;color:var(--text-muted);font-weight:600;text-transform:uppercase;letter-spacing:.5px}
.calc-group input,.calc-group select{background:var(--card);border:1px solid var(--border);color:var(--text);padding:.65rem .9rem;border-radius:8px;font-size:.95rem;transition:border-color .2s;font-family:var(--font)}
.calc-group input:focus,.calc-group select:focus{outline:none;border-color:var(--primary)}
.calc-group input::placeholder{color:var(--text-muted);opacity:.6}
.calc-btn{background:linear-gradient(135deg,var(--primary),var(--primary-dark));color:#fff;border:none;padding:.75rem 1.8rem;border-radius:8px;font-size:.95rem;font-weight:600;cursor:pointer;transition:all .2s;font-family:var(--font)}
.calc-btn:hover{transform:translateY(-1px);box-shadow:0 4px 16px rgba(99,102,241,.4)}
.calc-btn:active{transform:translateY(0)}

/* ===== RESULT CARD ===== */
.result-card{background:var(--card);border-radius:var(--radius);padding:1.2rem 1.5rem;margin-top:1rem;display:none}
.result-card.show{display:block;animation:fadeIn .3s ease}
.result-card__title{font-size:.82rem;color:var(--text-muted);text-transform:uppercase;letter-spacing:.5px;margin-bottom:.6rem}
.result-card__grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:.8rem}
.result-item{text-align:center;padding:.8rem;background:var(--surface);border-radius:8px}
.result-item__value{font-size:1.5rem;font-weight:800;color:var(--primary-light)}
.result-item__value.accent{color:var(--accent)}
.result-item__value.success{color:var(--success)}
.result-item__value.warning{color:var(--warning)}
.result-item__value.danger{color:var(--danger)}
.result-item__label{font-size:.78rem;color:var(--text-muted);margin-top:.2rem}

/* ===== CHART CONTAINER ===== */
.chart-wrap{background:var(--card);border-radius:var(--radius);padding:1.2rem;margin-top:1rem;display:none}
.chart-wrap.show{display:block;animation:fadeIn .3s ease}
.chart-wrap canvas{max-height:300px}

/* ===== EXAMPLE BOX ===== */
.example-box{background:rgba(34,211,238,.06);border:1px solid rgba(34,211,238,.2);border-radius:8px;padding:1rem 1.2rem;margin-top:1rem}
.example-box__title{font-size:.82rem;font-weight:700;color:var(--accent);margin-bottom:.3rem}
.example-box__text{font-size:.85rem;color:var(--text-muted);line-height:1.5}

/* ===== FOOTER ===== */
.site-footer{text-align:center;padding:2rem;color:var(--text-muted);font-size:.85rem;border-top:1px solid var(--border);margin-top:2rem}

/* ===== ANIMATIONS ===== */
@keyframes fadeIn{from{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}

/* ===== RESPONSIVE ===== */
@media(max-width:768px){
  .hero h1{font-size:2rem}
  .domains-grid{grid-template-columns:1fr;padding:1rem}
  .calc-grid,.calc-grid.cols-3{grid-template-columns:1fr}
  .result-card__grid{grid-template-columns:1fr 1fr}
  .topnav{padding:.8rem 1rem}
  .topnav__links{gap:.8rem}
  .accordion{padding:0 1rem 2rem}
  .page-header{padding:1.5rem 1rem 1rem}
  .use-case{margin:0 1rem 1rem}
}
@media(max-width:480px){
  .topnav__links{display:none}
  .result-card__grid{grid-template-columns:1fr}
}