/* ============================================================
   CSTI Acoustics — Design System v0.1  (the "$10K" language)
   Premium industrial-B2B: precise, technical, restrained.
   Safety-orange is reserved for the SINGLE primary action.
   Reusable across the tools suite and, eventually, the site.
   ============================================================ */
:root{
  /* Brand */
  --navy:#0A2540; --navy-700:#0f2c48; --navy-500:#173a5c;
  --steel:#2E5C8A; --steel-300:#6f9bc7;
  --orange:#FF6B35; --orange-600:#E85A2A;      /* PRIMARY ACTION ONLY */
  /* Cool-biased neutrals (chosen, not defaulted) */
  --paper:#eaeff5; --card:#ffffff; --card-2:#f5f8fc;
  --ink:#0f1e2e; --muted:#55697e; --line:#d8e1ec; --line-strong:#c2cede;
  /* Semantic (separate from the accent) */
  --ok:#0e8f63; --ok-bg:rgba(14,143,99,.12);
  --warn:#b7791f; --warn-bg:rgba(183,121,31,.13);
  --danger:#c0341b; --danger-bg:rgba(192,52,27,.10);
  /* System */
  --shadow-sm:0 1px 2px rgba(15,30,46,.06);
  --shadow:0 1px 2px rgba(15,30,46,.05),0 8px 28px rgba(15,30,46,.08);
  --radius:12px; --radius-sm:8px;
  --sans:system-ui,-apple-system,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
  --mono:"SFMono-Regular",Consolas,"Liberation Mono",Menlo,monospace;
  --maxw:1080px;
}
@media (prefers-color-scheme:dark){
  :root{
    --paper:#0a1420; --card:#101f2e; --card-2:#0c1a27;
    --ink:#e6edf4; --muted:#9fb1c4; --line:#20364c; --line-strong:#2b445e;
    --steel-300:#7ea6d1;
    --ok-bg:rgba(14,143,99,.18); --warn-bg:rgba(183,121,31,.18); --danger-bg:rgba(192,52,27,.16);
    --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 34px rgba(0,0,0,.38);
  }
}
:root[data-theme="light"]{--paper:#eaeff5;--card:#fff;--ink:#0f1e2e;--muted:#55697e;--line:#d8e1ec}
:root[data-theme="dark"]{--paper:#0a1420;--card:#101f2e;--ink:#e6edf4;--muted:#9fb1c4;--line:#20364c}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{margin:0;background:var(--paper);color:var(--ink);font-family:var(--sans);
  font-size:16.5px;line-height:1.6;-webkit-font-smoothing:antialiased;text-rendering:optimizeLegibility}
a{color:var(--steel);text-underline-offset:2px}
@media (prefers-color-scheme:dark){a{color:var(--steel-300)}}
.wrap{max-width:var(--maxw);margin:0 auto;padding:0 24px}

/* ---- Header / nav ---- */
.site-head{background:var(--navy);color:#dfeaf6;position:sticky;top:0;z-index:50;
  border-bottom:1px solid rgba(255,255,255,.08)}
.site-head .wrap{display:flex;align-items:center;gap:20px;height:64px}
.brand{display:flex;align-items:center;gap:10px;font-weight:800;letter-spacing:-.01em;color:#fff;text-decoration:none;font-size:1.05rem}
.brand .mark{width:26px;height:26px;flex:none}
.logo-img{height:34px;width:auto;display:block}
.site-head nav,.nav{margin-left:auto;display:flex;gap:22px;align-items:center;flex-wrap:wrap}
.site-head nav a,.nav a{color:#b9cbe0;text-decoration:none;font-size:.93rem;font-weight:500;white-space:nowrap}
.site-head nav a:hover,.nav a:hover{color:#fff}
.nav .cta{background:var(--orange);color:#fff !important;padding:9px 16px;border-radius:8px;font-weight:700;box-shadow:0 6px 16px rgba(255,107,53,.3)}
.nav .cta:hover{background:#E85A2A}
.tel{display:inline-flex;align-items:center;gap:7px;color:#fff !important;font-weight:700;font-variant-numeric:tabular-nums}
/* Mobile nav (hamburger dropdown) */
.nav-toggle{display:none;background:none;border:0;color:#fff;cursor:pointer;padding:6px;margin-left:auto;border-radius:8px}
@media(max-width:900px){
  .site-head .wrap{position:relative}
  .nav-toggle{display:inline-flex;align-items:center}
  .nav-toggle svg{width:26px;height:26px}
  .site-head .nav{position:absolute;top:100%;left:0;right:0;flex-direction:column;align-items:stretch;gap:0;
    background:var(--navy);border-top:1px solid rgba(255,255,255,.1);box-shadow:0 16px 30px rgba(0,0,0,.38);
    padding:6px 0 12px;display:none;z-index:70}
  .site-head .nav.open{display:flex}
  .site-head .nav a{width:100%;padding:13px 24px;font-size:1rem;white-space:normal}
  .site-head .nav a.hide-sm{display:block}
  .site-head .nav .tel{padding:13px 24px}
  .site-head .nav .cta{margin:10px 20px 4px;justify-content:center;text-align:center}
}

/* ---- Breadcrumb ---- */
.crumb{font-size:.82rem;color:var(--muted);padding:16px 0 0;letter-spacing:.01em}
.crumb a{color:var(--muted);text-decoration:none}.crumb a:hover{color:var(--steel)}

/* ---- Hero ---- */
.tool-hero{padding:22px 0 6px}
.eyebrow{font-size:12px;letter-spacing:.2em;text-transform:uppercase;color:var(--orange);font-weight:800;margin:0 0 10px}
.tool-hero h1{font-size:clamp(1.8rem,3.6vw,2.6rem);line-height:1.08;letter-spacing:-.02em;margin:0 0 12px;font-weight:800;text-wrap:balance}
.tool-hero p.sub{font-size:1.08rem;color:var(--muted);max-width:65ch;margin:0}
.byline{display:inline-flex;align-items:center;gap:9px;margin-top:16px;padding:7px 13px;background:var(--card);
  border:1px solid var(--line);border-radius:999px;font-size:.85rem;color:var(--muted);box-shadow:var(--shadow-sm)}
.byline b{color:var(--ink);font-weight:700}
.byline .seal{width:16px;height:16px;color:var(--steel)}

/* ---- Layout grid ---- */
.tool-grid{display:grid;grid-template-columns:1.15fr .85fr;gap:22px;margin:26px 0 8px;align-items:start}
@media(max-width:860px){.tool-grid{grid-template-columns:1fr}}

/* ---- Card ---- */
.card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:22px 24px}
.card h2{font-size:1.15rem;letter-spacing:-.01em;margin:0 0 4px;font-weight:800}
.card .hint{font-size:.86rem;color:var(--muted);margin:0 0 16px}
.card.sticky{position:sticky;top:84px}

/* ---- Inputs ---- */
.rowset{display:flex;flex-direction:column;gap:10px}
.exprow{display:grid;grid-template-columns:1fr 1fr auto;gap:10px;align-items:end}
label{display:block;font-size:.78rem;text-transform:uppercase;letter-spacing:.06em;color:var(--muted);font-weight:700;margin:0 0 5px}
input[type=number]{width:100%;padding:11px 12px;border:1.5px solid var(--line-strong);border-radius:var(--radius-sm);
  background:var(--card-2);color:var(--ink);font-size:1.05rem;font-family:var(--mono);font-variant-numeric:tabular-nums;
  transition:border-color .15s,box-shadow .15s}
input[type=number]:focus{outline:none;border-color:var(--steel);box-shadow:0 0 0 3px rgba(46,92,138,.16)}
.icon-btn{border:1.5px solid var(--line-strong);background:var(--card-2);color:var(--muted);width:44px;height:44px;
  border-radius:var(--radius-sm);font-size:1.3rem;line-height:1;cursor:pointer;transition:.15s}
.icon-btn:hover{border-color:var(--danger);color:var(--danger)}
.addrow{margin-top:12px;background:none;border:1.5px dashed var(--line-strong);color:var(--steel);
  padding:10px;width:100%;border-radius:var(--radius-sm);font-weight:700;cursor:pointer;font-size:.9rem;transition:.15s}
.addrow:hover{border-color:var(--steel);background:var(--card-2)}

/* Standard toggle */
.seg{display:inline-flex;border:1.5px solid var(--line-strong);border-radius:999px;padding:3px;background:var(--card-2);margin-bottom:18px}
.seg button{border:0;background:none;padding:7px 16px;border-radius:999px;font-weight:700;font-size:.85rem;color:var(--muted);cursor:pointer;transition:.15s}
.seg button[aria-pressed="true"]{background:var(--navy);color:#fff}

/* Buttons */
.btn{display:inline-flex;align-items:center;justify-content:center;gap:9px;font-weight:700;font-size:1rem;
  padding:13px 22px;border-radius:var(--radius-sm);cursor:pointer;border:1.5px solid transparent;text-decoration:none;transition:.15s}
.btn-primary{background:var(--orange);color:#fff;box-shadow:0 6px 16px rgba(255,107,53,.28)}
.btn-primary:hover{background:var(--orange-600);transform:translateY(-1px)}
.btn-ghost{background:transparent;border-color:var(--navy);color:var(--navy)}
@media (prefers-color-scheme:dark){.btn-ghost{border-color:var(--steel-300);color:var(--steel-300)}}
.btn-block{width:100%}

/* ---- Result readouts (instrument panel) ---- */
.readouts{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-bottom:6px}
.readout{background:var(--card-2);border:1px solid var(--line);border-radius:var(--radius-sm);padding:15px 16px;position:relative;overflow:hidden}
.readout .k{font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);font-weight:700}
.readout .v{font-size:2rem;font-weight:800;font-variant-numeric:tabular-nums;letter-spacing:-.02em;line-height:1.1;margin-top:3px}
.readout .u{font-size:.95rem;color:var(--muted);font-weight:600}
.readout .flag{font-size:.74rem;font-weight:800;text-transform:uppercase;letter-spacing:.05em;margin-top:6px;display:inline-block}
.readout[data-state=ok]{border-color:rgba(14,143,99,.4)} .readout[data-state=ok] .flag{color:var(--ok)}
.readout[data-state=warn]{border-color:rgba(183,121,31,.5)} .readout[data-state=warn] .flag{color:var(--warn)}
.readout[data-state=danger]{border-color:rgba(192,52,27,.5)} .readout[data-state=danger] .flag{color:var(--danger)}
.readout[data-state=danger]::before,.readout[data-state=warn]::before{content:"";position:absolute;left:0;top:0;bottom:0;width:4px}
.readout[data-state=danger]::before{background:var(--danger)} .readout[data-state=warn]::before{background:var(--warn)}

/* Alert banner (threshold trip -> lead) */
.alert{border-radius:var(--radius);padding:18px 20px;margin:16px 0 0;display:flex;gap:14px;align-items:flex-start}
.alert.danger{background:var(--danger-bg);border:1px solid rgba(192,52,27,.35)}
.alert.ok{background:var(--ok-bg);border:1px solid rgba(14,143,99,.35)}
.alert .ic{font-size:1.3rem;line-height:1.3;flex:none}
.alert h3{margin:0 0 4px;font-size:1rem;font-weight:800}
.alert p{margin:0 0 12px;font-size:.92rem;color:var(--muted)}
.alert.ok p:last-child,.alert.danger p:last-child{margin-bottom:0}

/* Formula / method block */
.method{background:var(--navy);color:#cfe0f1;border-radius:var(--radius);padding:22px 24px;margin-top:22px;box-shadow:var(--shadow)}
.method h2{color:#fff;font-size:1.1rem;margin:0 0 12px}
.formula{font-family:var(--mono);font-size:.95rem;background:rgba(255,255,255,.06);border:1px solid rgba(255,255,255,.1);
  border-radius:var(--radius-sm);padding:14px 16px;margin:0 0 12px;overflow-x:auto;white-space:nowrap}
.method .note{font-size:.86rem;color:#9fb8d2;margin:0}
.method a{color:#ffb499}

/* FAQ (AEO) */
.faq{margin-top:22px}
.faq h2{font-size:1.3rem;letter-spacing:-.01em;margin:0 0 12px}
.faq details{background:var(--card);border:1px solid var(--line);border-radius:var(--radius-sm);padding:14px 18px;margin-bottom:10px;box-shadow:var(--shadow-sm)}
.faq summary{font-weight:700;cursor:pointer;list-style:none}
.faq summary::-webkit-details-marker{display:none}
.faq summary::after{content:"+";float:right;color:var(--steel);font-weight:800}
.faq details[open] summary::after{content:"–"}
.faq p{color:var(--muted);font-size:.94rem;margin:10px 0 0}

/* Footer (shared .foot-grid — matches site.css) */
.site-foot{background:var(--navy);color:#9fb4cc;padding:48px 0 28px;margin-top:56px}
.site-foot .wrap{display:block}
.foot-grid{display:grid;grid-template-columns:2fr 1fr 1fr 1.2fr;gap:32px;padding-bottom:26px;border-bottom:1px solid rgba(255,255,255,.1)}
@media(max-width:820px){.foot-grid{grid-template-columns:1fr 1fr}}
@media(max-width:520px){.foot-grid{grid-template-columns:1fr}}
.site-foot h4{color:#fff;font-size:1rem;margin:0 0 14px}
.site-foot ul{list-style:none;padding:0;margin:0}
.site-foot li{margin-bottom:9px}
.site-foot a{color:#a9bdd4;text-decoration:none;font-size:.92rem}
.site-foot a:hover{color:#fff}
.site-foot .about p{font-size:.92rem;line-height:1.6;color:#a9bdd4;margin:12px 0}
.site-foot .creds{display:flex;flex-wrap:wrap;gap:7px;margin-top:6px}
.badge{font-size:.68rem;font-weight:800;letter-spacing:.04em;text-transform:uppercase;color:#cddbec;
  border:1px solid rgba(255,255,255,.18);border-radius:999px;padding:5px 10px}
.foot-bottom{display:flex;justify-content:space-between;flex-wrap:wrap;gap:10px;padding-top:20px;font-size:.85rem;color:#7f96b0}
.foot-bottom .np b{color:#cddbec}
.tel-lg{color:var(--orange) !important;font-weight:800;font-variant-numeric:tabular-nums}
.disclaimer{font-size:.78rem;color:var(--muted);margin-top:14px;max-width:70ch}

/* utility */
.mono{font-family:var(--mono);font-variant-numeric:tabular-nums}
.section-t{font-size:.78rem;text-transform:uppercase;letter-spacing:.1em;color:var(--muted);font-weight:800;margin:0 0 12px}

/* Toolkit hub */
.hub-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(290px,1fr));gap:18px;margin:26px 0 8px}
.hub-card{background:var(--card);border:1px solid var(--line);border-radius:var(--radius);padding:22px 24px;box-shadow:var(--shadow);display:flex;flex-direction:column;text-decoration:none;color:inherit;transition:transform .18s,box-shadow .18s}
a.hub-card:hover{transform:translateY(-3px);box-shadow:0 18px 44px rgba(15,30,46,.14)}
.hub-card .ic{width:38px;height:38px;color:var(--steel);margin-bottom:14px}
@media (prefers-color-scheme:dark){.hub-card .ic{color:var(--steel-lt)}}
.hub-card h3{margin:0 0 6px;font-size:1.12rem;letter-spacing:-.01em;color:var(--ink)}
.hub-card p{margin:0 0 8px;color:var(--muted);font-size:.92rem;flex:1}
.hub-card .std{font-family:var(--mono);font-size:.72rem;color:var(--steel);margin:0 0 14px}
@media (prefers-color-scheme:dark){.hub-card .std{color:var(--steel-lt)}}
.hub-card .cardfoot{display:flex;align-items:center;gap:6px;font-size:.86rem;font-weight:800;letter-spacing:.02em}
.hub-card .cardfoot.live{color:var(--orange)}
.hub-card.soon{opacity:.7}
.hub-card .cardfoot.soon-tag{color:var(--muted);text-transform:uppercase;font-size:.72rem;letter-spacing:.08em}
@media (prefers-reduced-motion:reduce){*{transition:none !important}}