/* ============================================================
   CalcHub — Premium Design System
   ============================================================ */
:root{
  /* palette */
  --bg:#070b18;
  --bg-soft:#0d1424;
  --ink:#0f172a;
  --paper:#ffffff;
  --paper-2:#f8fafc;
  --muted:#64748b;
  --muted-2:#94a3b8;
  --border:#e8ecf3;
  --violet:#7c5cff;
  --indigo:#4f46e5;
  --cyan:#22d3ee;
  --green:#10b981;
  --grad: linear-gradient(135deg,#7c5cff 0%,#4f46e5 50%,#22d3ee 130%);
  --grad-soft: linear-gradient(135deg,#f5f3ff,#eef2ff 60%,#ecfeff);
  --shadow-sm: 0 1px 2px rgba(2,6,23,.06), 0 1px 1px rgba(2,6,23,.04);
  --shadow: 0 10px 30px -12px rgba(2,6,23,.18);
  --shadow-lg: 0 30px 60px -20px rgba(79,70,229,.35);
  --radius:18px;
  --radius-lg:26px;
}
*{margin:0;padding:0;box-sizing:border-box}
html,body{overflow-x:hidden;max-width:100%}
.calc-shell>*,.tools>*,.metrics>*,.multi>*,.row2>*,.donut-wrap>*,.cols>*,.measure-viz>*{min-width:0}
.tscroll{overflow-x:auto;-webkit-overflow-scrolling:touch;margin:10px 0}
img,svg,table{max-width:100%}
html{scroll-behavior:smooth}
body{
  font-family:"Inter",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
  color:var(--ink);background:var(--paper-2);line-height:1.65;
  -webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility;
}
a{color:var(--indigo);text-decoration:none;transition:color .2s}
a:hover{color:var(--violet)}
.wrap{max-width:1080px;margin:0 auto;padding:0 22px}
.narrow{max-width:780px}
section{padding:0}

/* ---------- NAV (glass, sticky) ---------- */
nav{
  position:sticky;top:0;z-index:50;
  background:rgba(255,255,255,.72);backdrop-filter:saturate(180%) blur(14px);
  border-bottom:1px solid rgba(15,23,42,.06);
}
nav .wrap{display:flex;align-items:center;justify-content:space-between;height:68px}
.logo{font-weight:800;font-size:1.25rem;letter-spacing:-.02em;color:var(--ink);display:flex;align-items:center;gap:9px}
.logo .mark{width:30px;height:30px;border-radius:9px;background:var(--grad);
  display:grid;place-items:center;color:#fff;font-weight:900;font-size:.95rem;box-shadow:var(--shadow-sm)}
.logo span{background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.nav-links{display:flex;align-items:center;gap:26px}
.nav-links a{color:var(--muted);font-weight:600;font-size:.93rem}
.nav-links a:hover{color:var(--ink)}
.nav-cta{background:var(--ink);color:#fff !important;padding:9px 16px;border-radius:11px;font-size:.88rem}
.nav-cta:hover{background:#1e293b}

/* ---------- HERO ---------- */
.hero{position:relative;overflow:hidden;background:var(--bg);color:#fff;
  padding:96px 0 110px;text-align:center}
.hero::before{ /* gradient mesh glow */
  content:"";position:absolute;inset:-30% -10% auto -10%;height:80%;
  background:
    radial-gradient(40% 50% at 25% 20%,rgba(124,92,255,.55),transparent 60%),
    radial-gradient(40% 50% at 80% 10%,rgba(34,211,238,.40),transparent 55%),
    radial-gradient(50% 60% at 60% 70%,rgba(79,70,229,.45),transparent 60%);
  filter:blur(18px);pointer-events:none;
}
.hero::after{ /* subtle grid */
  content:"";position:absolute;inset:0;opacity:.10;pointer-events:none;
  background-image:linear-gradient(rgba(255,255,255,.7) 1px,transparent 1px),
                   linear-gradient(90deg,rgba(255,255,255,.7) 1px,transparent 1px);
  background-size:46px 46px;mask-image:radial-gradient(70% 60% at 50% 40%,#000,transparent);
}
.hero .wrap{position:relative;z-index:1}
.pill{display:inline-flex;align-items:center;gap:8px;
  background:rgba(255,255,255,.08);border:1px solid rgba(255,255,255,.18);
  padding:7px 15px;border-radius:999px;font-size:.82rem;color:#cbd5e1;margin-bottom:26px;
  backdrop-filter:blur(6px)}
.pill .dot{width:7px;height:7px;border-radius:50%;background:var(--green);box-shadow:0 0 0 4px rgba(16,185,129,.25)}
.hero h1{font-size:clamp(2.1rem,5vw,3.5rem);line-height:1.06;letter-spacing:-.03em;font-weight:800;
  margin-bottom:20px}
.hero h1 em{font-style:normal;background:linear-gradient(120deg,#a78bfa,#22d3ee);
  -webkit-background-clip:text;background-clip:text;color:transparent}
.hero p.lead{font-size:1.18rem;color:#aab4c5;max-width:600px;margin:0 auto 36px}
.hero-cta{display:flex;gap:14px;justify-content:center;flex-wrap:wrap}

/* "what you can calculate" chips */
.hero-examples{display:flex;flex-wrap:wrap;gap:10px;justify-content:center;max-width:720px;margin:0 auto 34px}
.hero-examples span,.hero-examples a{display:inline-block;text-decoration:none;cursor:pointer;
  background:rgba(255,255,255,.07);border:1px solid rgba(255,255,255,.16);
  color:#cbd5e1;padding:9px 15px;border-radius:12px;font-size:.9rem;font-weight:500;
  backdrop-filter:blur(6px);transition:background .2s,color .2s,transform .15s}
.hero-examples span:hover,.hero-examples a:hover{background:rgba(255,255,255,.13);color:#fff;transform:translateY(-2px)}

/* trust row */
.trust{margin-top:40px;display:flex;gap:30px;justify-content:center;flex-wrap:wrap;
  color:#8895a9;font-size:.85rem}
.trust b{color:#e2e8f0}

/* ---------- BUTTONS ---------- */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:9px;
  border:none;cursor:pointer;font-weight:700;font-size:1rem;font-family:inherit;
  padding:15px 26px;border-radius:14px;transition:transform .15s ease, box-shadow .2s ease, background .2s}
.btn-primary{background:var(--grad);color:#fff;background-size:160% 160%;box-shadow:var(--shadow-lg)}
.btn-primary:hover{transform:translateY(-2px);background-position:100% 0;color:#fff}
.btn-ghost{background:rgba(255,255,255,.06);color:#fff;border:1px solid rgba(255,255,255,.2)}
.btn-ghost:hover{background:rgba(255,255,255,.12);color:#fff;transform:translateY(-2px)}
.btn-block{width:100%}

/* ---------- AD SLOTS ---------- */
.ad{background:repeating-linear-gradient(45deg,#eef2ff,#eef2ff 10px,#f5f3ff 10px,#f5f3ff 20px);
  border:1px dashed #c7d2fe;border-radius:14px;color:#7c5cff;text-align:center;
  padding:20px;margin:30px 0;font-size:.8rem;font-weight:700;letter-spacing:.03em}

/* ---------- SECTION HEADERS ---------- */
.sec{padding:74px 0}
.sec-head{text-align:center;max-width:620px;margin:0 auto 44px}
.eyebrow{font-size:.78rem;font-weight:800;letter-spacing:.14em;text-transform:uppercase;
  background:var(--grad);-webkit-background-clip:text;background-clip:text;color:transparent}
.sec-head h2{font-size:clamp(1.7rem,3.5vw,2.4rem);letter-spacing:-.02em;margin:10px 0 12px}
.sec-head p{color:var(--muted);font-size:1.05rem}

/* ---------- TOOL CARDS ---------- */
.tools{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:20px}
.tool{position:relative;background:var(--paper);border:1px solid var(--border);
  border-radius:var(--radius-lg);padding:28px;display:block;overflow:hidden;
  box-shadow:var(--shadow-sm);transition:transform .22s ease, box-shadow .22s ease, border-color .22s}
.tool::before{content:"";position:absolute;inset:0;border-radius:inherit;padding:1px;
  background:var(--grad);-webkit-mask:linear-gradient(#000 0 0) content-box,linear-gradient(#000 0 0);
  -webkit-mask-composite:xor;mask-composite:exclude;opacity:0;transition:opacity .22s}
.tool:hover{transform:translateY(-6px);box-shadow:var(--shadow);text-decoration:none}
.tool:hover::before{opacity:1}
.tool .ico{width:52px;height:52px;border-radius:14px;display:grid;place-items:center;
  font-size:1.5rem;background:var(--grad-soft);box-shadow:inset 0 0 0 1px rgba(124,92,255,.15);margin-bottom:16px}
.tool h3{font-size:1.18rem;letter-spacing:-.01em;color:var(--ink);margin-bottom:6px;display:flex;align-items:center;gap:8px}
.tool p{color:var(--muted);font-size:.94rem}
.tool .go{margin-top:14px;font-weight:700;font-size:.9rem;color:var(--indigo);display:inline-flex;gap:6px;align-items:center}
.tool .go .arrow{transition:transform .2s}
.tool:hover .go .arrow{transform:translateX(4px)}
.badge-soon{font-size:.66rem;font-weight:800;letter-spacing:.05em;background:#f1f5f9;color:var(--muted);
  padding:3px 8px;border-radius:999px;text-transform:uppercase}
.tool.soon{opacity:.78}
.tool.soon:hover{transform:none;box-shadow:var(--shadow-sm)}

/* ---------- CALCULATOR LAYOUT ---------- */
.calc-shell{display:grid;grid-template-columns:1.05fr .95fr;gap:24px;align-items:start}
.calc-card{background:var(--paper);border:1px solid var(--border);border-radius:var(--radius-lg);
  padding:30px;box-shadow:var(--shadow)}
.calc-card h3{font-size:1.05rem;margin-bottom:20px;letter-spacing:-.01em}
.field{margin-bottom:20px}
.field-top{display:flex;justify-content:space-between;align-items:baseline;margin-bottom:8px}
.field label{font-weight:700;font-size:.9rem}
.field .hint{font-size:.78rem;color:var(--muted-2)}
.input-wrap{position:relative}
.input-wrap .affix{position:absolute;top:50%;transform:translateY(-50%);left:14px;color:var(--muted);font-weight:700}
.input-wrap.has-affix input{padding-left:30px}
.field input[type=number]{width:100%;padding:13px 14px;border:1.5px solid var(--border);
  border-radius:12px;font-size:1.05rem;font-weight:600;font-family:inherit;background:#fff;
  transition:border-color .18s, box-shadow .18s}
.field input[type=number]:focus{outline:none;border-color:var(--violet);
  box-shadow:0 0 0 4px rgba(124,92,255,.14)}
input[type=range]{-webkit-appearance:none;appearance:none;width:100%;height:6px;border-radius:999px;
  margin-top:14px;background:#e8ecf3;cursor:pointer}
input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;width:22px;height:22px;border-radius:50%;
  background:#fff;border:none;box-shadow:0 2px 8px rgba(79,70,229,.45),0 0 0 2px var(--violet) inset;cursor:pointer;
  transition:transform .12s}
input[type=range]::-webkit-slider-thumb:hover{transform:scale(1.12)}
input[type=range]::-moz-range-thumb{width:22px;height:22px;border-radius:50%;background:#fff;
  border:2px solid var(--violet);box-shadow:0 2px 8px rgba(79,70,229,.45);cursor:pointer}

/* result panel */
.result-card{position:relative;overflow:hidden;border-radius:var(--radius-lg);
  background:var(--bg);color:#fff;padding:32px;box-shadow:var(--shadow-lg)}
.result-card::before{content:"";position:absolute;inset:-40% -20% auto -20%;height:90%;
  background:radial-gradient(50% 60% at 30% 20%,rgba(124,92,255,.6),transparent 60%),
             radial-gradient(50% 60% at 85% 10%,rgba(34,211,238,.4),transparent 55%);
  filter:blur(10px)}
.result-card>*{position:relative;z-index:1}
.result-card .cap{font-size:.74rem;font-weight:800;letter-spacing:.14em;text-transform:uppercase;color:#a5b4fc}
.result-card .big{font-size:clamp(2.4rem,6vw,3.2rem);font-weight:800;letter-spacing:-.03em;line-height:1;margin:6px 0 4px}
.result-card .sub{color:#94a3b8;font-size:.9rem;margin-bottom:22px}
.metrics{display:grid;grid-template-columns:1fr 1fr;gap:12px}
.metric{background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.1);border-radius:14px;padding:14px}
.metric small{display:block;color:#94a3b8;font-size:.7rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase}
.metric b{font-size:1.3rem;font-weight:700;letter-spacing:-.02em}
.bar-split{margin-top:20px}
.bar-split .track{height:10px;border-radius:999px;background:rgba(255,255,255,.12);overflow:hidden;display:flex}
.bar-split .track i{display:block;height:100%}
.bar-split .lp{background:#22d3ee}.bar-split .li{background:#7c5cff}
.bar-split .legend{display:flex;gap:18px;margin-top:10px;font-size:.78rem;color:#cbd5e1}
.bar-split .legend span{display:flex;align-items:center;gap:6px}
.bar-split .legend i{width:9px;height:9px;border-radius:3px;display:inline-block}

/* ---------- ARTICLE ---------- */
article{background:var(--paper);border:1px solid var(--border);border-radius:var(--radius-lg);
  padding:38px;box-shadow:var(--shadow-sm)}
article h2{font-size:1.5rem;letter-spacing:-.02em;margin:30px 0 12px}
article h2:first-child{margin-top:0}
article p,article li{color:#334155}
article ul{margin:0 0 0 22px}
article .formula{background:var(--grad-soft);border:1px solid #e0e7ff;border-radius:14px;
  padding:18px 20px;font-size:1.1rem;text-align:center;font-weight:600;color:var(--indigo);margin:6px 0}
.faq details{border:1px solid var(--border);border-radius:14px;margin-bottom:12px;padding:4px 20px;
  transition:border-color .2s, background .2s}
.faq details[open]{border-color:#c7d2fe;background:#fafaff}
.faq summary{font-weight:700;cursor:pointer;padding:14px 0;list-style:none;display:flex;justify-content:space-between;align-items:center}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";font-size:1.4rem;color:var(--violet);font-weight:600;transition:transform .2s}
.faq details[open] summary::after{transform:rotate(45deg)}
.faq details p{padding:0 0 16px;color:var(--muted)}

/* ---------- CTA STRIP ---------- */
.cta-strip{background:var(--bg);border-radius:var(--radius-lg);text-align:center;color:#fff;
  padding:54px 30px;position:relative;overflow:hidden}
.cta-strip::before{content:"";position:absolute;inset:0;
  background:radial-gradient(50% 80% at 50% 0,rgba(124,92,255,.45),transparent 60%)}
.cta-strip>*{position:relative;z-index:1}
.cta-strip h2{font-size:1.9rem;letter-spacing:-.02em;margin-bottom:10px}
.cta-strip p{color:#aab4c5;margin-bottom:24px}

/* ---------- FOOTER ---------- */
/* custom tool helpers (percentage / bmi / age) */
.multi{display:grid;grid-template-columns:1fr 1fr;gap:20px}
.mini-out{font-size:2rem;font-weight:800;letter-spacing:-.02em;color:var(--indigo);margin-top:14px;
  background:var(--grad-soft);border:1px solid #e0e7ff;border-radius:14px;padding:14px 18px;min-height:64px;
  display:flex;align-items:center}
.row2{display:grid;grid-template-columns:1fr 1fr;gap:14px}
.seg{display:inline-flex;background:var(--paper-2);border:1px solid var(--border);border-radius:12px;
  padding:4px;margin-bottom:20px;gap:4px}
.seg button{border:none;background:transparent;padding:9px 18px;border-radius:9px;font-weight:700;
  font-family:inherit;font-size:.92rem;color:var(--muted);cursor:pointer;transition:all .15s}
.seg button.active{background:#fff;color:var(--indigo);box-shadow:var(--shadow-sm)}
.bmi-scale{display:flex;height:12px;border-radius:999px;overflow:hidden;margin:18px 0 8px}
.bmi-scale i{display:block;height:100%}
.bmi-legend{display:flex;justify-content:space-between;font-size:.72rem;color:#94a3b8;font-weight:600}
.cat-pill{display:inline-block;padding:6px 14px;border-radius:999px;font-weight:700;font-size:.95rem;margin-top:6px}

/* macro donut chart */
.donut-wrap{display:flex;align-items:center;gap:24px;margin:10px 0 4px;flex-wrap:wrap;justify-content:center}
.donut{transform:rotate(-90deg)}
.donut circle{transition:stroke-dasharray .5s ease}
.mlegend{display:flex;flex-direction:column;gap:10px}
.mlegend div{display:flex;align-items:center;gap:9px;font-size:.95rem;color:#cbd5e1}
.mlegend i{width:13px;height:13px;border-radius:4px;display:inline-block}
.mlegend b{color:#fff;font-weight:700}

/* body-fat measurement diagram */
.measure-viz{display:flex;gap:26px;align-items:center;flex-wrap:wrap;
  background:var(--grad-soft);border:1px solid #e0e7ff;border-radius:16px;padding:22px;margin:6px 0 4px}
.measure-viz ol{margin:0 0 0 18px;color:#334155}
.measure-viz li{margin-bottom:8px}
.measure-viz li b{color:var(--ink)}
.mfig{flex:0 0 auto}
.mfig .mline{stroke:#6366f1;stroke-width:2;stroke-dasharray:4 3}
.mfig .mlabel{fill:#4f46e5;font:700 11px Inter,sans-serif}
.mfig .body{fill:#c7d2fe}

/* reference tables */
.ptable{width:100%;border-collapse:collapse;margin:10px 0;font-size:.98rem}
.ptable th,.ptable td{padding:12px 14px;border-bottom:1px solid var(--border);text-align:left}
.ptable thead th{background:var(--paper-2);font-size:.8rem;text-transform:uppercase;letter-spacing:.05em;color:var(--muted)}
.ptable tbody tr:hover{background:#fafaff}

footer{background:var(--bg);color:#94a3b8;padding:50px 0 36px;margin-top:74px}
footer .cols{display:flex;justify-content:space-between;gap:30px;flex-wrap:wrap;margin-bottom:30px}
footer .logo{color:#fff}
footer h4{color:#e2e8f0;font-size:.85rem;text-transform:uppercase;letter-spacing:.1em;margin-bottom:14px}
footer a{color:#94a3b8;display:block;margin-bottom:8px;font-size:.92rem}
footer a:hover{color:#fff}
footer .bar{border-top:1px solid rgba(255,255,255,.08);padding-top:22px;font-size:.82rem;text-align:center}

/* ---------- ANIM ---------- */
@keyframes pop{0%{transform:scale(.96);opacity:.4}100%{transform:scale(1);opacity:1}}
.result-card.show .big{animation:pop .35s ease}
.reveal{opacity:0;transform:translateY(16px);transition:opacity .6s ease, transform .6s ease}
.reveal.in{opacity:1;transform:none}

/* ---------- RESPONSIVE ---------- */
@media(max-width:820px){
  .calc-shell{grid-template-columns:1fr}
  .nav-links a:not(.nav-cta){display:none}
}
@media(max-width:520px){
  .metrics{grid-template-columns:1fr}
  .hero{padding:72px 0 84px}
}