/* VoIP Toolbox — main stylesheet. No external dependencies. */
:root{
  --bg:#f7f8fb; --surface:#ffffff; --surface-2:#f0f2f7; --border:#e2e6ee;
  --text:#141a26; --muted:#5b6578; --accent:#0e7c86; --accent-2:#0a5f67; --accent-soft:#e3f4f5;
  --ok:#1f8a4c; --warn:#b7791f; --bad:#c0392b;
  --c1:#6b7280; --c2:#1f8a4c; --c3:#2563eb; --c4:#b7791f; --c5:#c0392b; --c6:#7c3aed;
  --radius:14px; --shadow:0 1px 2px rgba(20,26,38,.05),0 4px 16px rgba(20,26,38,.06);
  --mono:ui-monospace,SFMono-Regular,Menlo,Consolas,"Liberation Mono",monospace;
  --sans:system-ui,-apple-system,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  color-scheme:light;
}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]){
  --bg:#0d1117; --surface:#151b24; --surface-2:#1b2330; --border:#273142;
  --text:#e6eaf2; --muted:#9aa5b8; --accent:#34c3cd; --accent-2:#5fd6de; --accent-soft:#12303a;
  --ok:#3fb978; --warn:#e0a84a; --bad:#ef6b5b;
  --c1:#9aa5b8; --c2:#3fb978; --c3:#6a9cff; --c4:#e0a84a; --c5:#ef6b5b; --c6:#a78bfa;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 4px 16px rgba(0,0,0,.25); color-scheme:dark;}}
:root[data-theme="dark"]{
  --bg:#0d1117; --surface:#151b24; --surface-2:#1b2330; --border:#273142;
  --text:#e6eaf2; --muted:#9aa5b8; --accent:#34c3cd; --accent-2:#5fd6de; --accent-soft:#12303a;
  --ok:#3fb978; --warn:#e0a84a; --bad:#ef6b5b;
  --c1:#9aa5b8; --c2:#3fb978; --c3:#6a9cff; --c4:#e0a84a; --c5:#ef6b5b; --c6:#a78bfa;
  --shadow:0 1px 2px rgba(0,0,0,.3),0 4px 16px rgba(0,0,0,.25); color-scheme:dark;}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);font:16px/1.65 var(--sans);}
a{color:var(--accent);text-decoration-thickness:1px;text-underline-offset:2px}
a:hover{color:var(--accent-2)}
img,svg{max-width:100%}
code,kbd,pre{font-family:var(--mono);font-size:.92em}
code{background:var(--surface-2);padding:.1em .35em;border-radius:6px}
pre{background:var(--surface-2);padding:14px 16px;border-radius:10px;overflow:auto;border:1px solid var(--border)}
h1,h2,h3{line-height:1.25;letter-spacing:-.01em}
h1{font-size:clamp(1.8rem,4vw,2.6rem);margin:.2em 0 .4em}
h2{font-size:1.45rem;margin:2em 0 .6em}
h3{font-size:1.12rem;margin:1.6em 0 .4em}
.skip{position:absolute;left:-999px}.skip:focus{left:16px;top:8px;background:var(--surface);padding:8px 12px;z-index:99;border-radius:8px}
.wrap{max-width:1120px;margin:0 auto;padding:0 16px}
.narrow{max-width:780px}

/* Header */
.site-header{position:sticky;top:0;z-index:20;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:saturate(1.4) blur(10px);border-bottom:1px solid var(--border)}
.nav{display:flex;align-items:center;gap:18px;height:62px}
.brand{display:flex;align-items:center;gap:9px;font-weight:700;color:var(--text);text-decoration:none;font-size:1.08rem;white-space:nowrap}
.brand svg{width:28px;height:28px}
.nav-links{display:flex;gap:4px;margin-left:auto;list-style:none;padding:0}
.nav-links a{color:var(--muted);text-decoration:none;padding:8px 12px;border-radius:9px;font-weight:500;font-size:.95rem}
.nav-links a:hover,.nav-links a[aria-current="page"]{color:var(--text);background:var(--surface-2)}
.icon-btn{border:1px solid var(--border);background:var(--surface);color:var(--text);width:38px;height:38px;border-radius:10px;display:grid;place-items:center;cursor:pointer}
.menu-btn{display:none}
@media (max-width:820px){
  .menu-btn{display:grid;margin-left:auto}
  .nav-links{display:none;position:absolute;top:62px;left:0;right:0;flex-direction:column;background:var(--surface);border-bottom:1px solid var(--border);padding:8px 16px 16px;margin:0}
  .nav-links.open{display:flex}
}

/* Hero */
.hero{padding:64px 0 36px}
.eyebrow{display:inline-block;font-size:.8rem;font-weight:600;text-transform:uppercase;letter-spacing:.08em;color:var(--accent);background:var(--accent-soft);padding:4px 10px;border-radius:999px}
.lead{font-size:1.15rem;color:var(--muted);max-width:680px}
.hero-search{margin-top:22px;display:flex;gap:8px;max-width:560px}
.hero-search input{flex:1}

/* Cards / grid */
.grid{display:grid;gap:18px}
.grid-3{grid-template-columns:repeat(auto-fit,minmax(260px,1fr))}
.grid-2{grid-template-columns:repeat(auto-fit,minmax(320px,1fr))}
.card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:22px;box-shadow:var(--shadow)}
a.card{display:block;color:inherit;text-decoration:none;transition:transform .15s,border-color .15s}
a.card:hover{transform:translateY(-2px);border-color:var(--accent)}
.card h3{margin:.3em 0 .3em}
.card p{margin:0;color:var(--muted)}
.card .ico{width:42px;height:42px;border-radius:11px;background:var(--accent-soft);color:var(--accent);display:grid;place-items:center}
.card .ico svg{width:22px;height:22px}
.tag{display:inline-block;font-size:.75rem;font-weight:600;padding:2px 8px;border-radius:999px;background:var(--surface-2);color:var(--muted)}

/* Forms */
label{display:block;font-weight:600;font-size:.9rem;margin-bottom:6px}
.hint{font-weight:400;color:var(--muted);font-size:.82rem}
input,select{width:100%;font:inherit;color:var(--text);background:var(--surface);border:1px solid var(--border);border-radius:10px;padding:10px 12px;min-height:44px}
input:focus,select:focus{outline:2px solid var(--accent);outline-offset:1px;border-color:transparent}
input[type=range]{padding:0;min-height:auto;accent-color:var(--accent)}
.field{margin-bottom:16px}
.row{display:grid;grid-template-columns:repeat(auto-fit,minmax(160px,1fr));gap:14px}
.check{display:flex;align-items:center;gap:8px;font-weight:500}
.check input{width:18px;height:18px;min-height:auto}
.btn{display:inline-flex;align-items:center;gap:8px;font:inherit;font-weight:600;border:1px solid var(--accent);background:var(--accent);color:#fff;padding:10px 16px;border-radius:10px;cursor:pointer;text-decoration:none;min-height:44px}
:root[data-theme="dark"] .btn{color:#06222a}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .btn{color:#06222a}}
.btn:hover{filter:brightness(1.08);color:#fff}
.btn.ghost{background:transparent;color:var(--accent)}
.btn-row{display:flex;flex-wrap:wrap;gap:10px;margin-top:8px}

/* Tool layout */
.tool{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:22px;align-items:start}
@media (max-width:860px){.tool{grid-template-columns:1fr}}
.result-big{font-size:2.6rem;font-weight:750;letter-spacing:-.02em;line-height:1.1}
.result-unit{font-size:1rem;color:var(--muted);font-weight:500;margin-left:4px}
.stats{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:12px;margin-top:16px}
.stat{background:var(--surface-2);border-radius:10px;padding:12px}
.stat .k{font-size:.8rem;color:var(--muted)}
.stat .v{font-weight:700;font-size:1.15rem;font-variant-numeric:tabular-nums}
.meter{height:12px;border-radius:999px;background:linear-gradient(90deg,var(--bad),var(--warn) 45%,var(--ok));position:relative;margin:18px 0 6px}
.meter i{position:absolute;top:-5px;width:4px;height:22px;background:var(--text);border-radius:2px;transform:translateX(-2px);transition:left .25s}
.meter-scale{display:flex;justify-content:space-between;font-size:.75rem;color:var(--muted)}
.badge{display:inline-block;padding:3px 10px;border-radius:999px;font-weight:700;font-size:.85rem}
.b-ok{background:color-mix(in srgb,var(--ok) 15%,transparent);color:var(--ok)}
.b-warn{background:color-mix(in srgb,var(--warn) 18%,transparent);color:var(--warn)}
.b-bad{background:color-mix(in srgb,var(--bad) 15%,transparent);color:var(--bad)}

/* Tables */
.table-wrap{overflow-x:auto;border:1px solid var(--border);border-radius:var(--radius);background:var(--surface)}
table{border-collapse:collapse;width:100%;font-size:.95rem}
th,td{text-align:left;padding:10px 14px;border-bottom:1px solid var(--border);vertical-align:top}
th{background:var(--surface-2);font-size:.82rem;text-transform:uppercase;letter-spacing:.04em;color:var(--muted)}
tr:last-child td{border-bottom:0}
td.num{font-variant-numeric:tabular-nums;white-space:nowrap}

/* SIP codes */
.code-pill{font-family:var(--mono);font-weight:700;padding:2px 8px;border-radius:7px;color:#fff;display:inline-block;min-width:48px;text-align:center}
.k1{background:var(--c1)}.k2{background:var(--c2)}.k3{background:var(--c3)}.k4{background:var(--c4)}.k5{background:var(--c5)}.k6{background:var(--c6)}
:root[data-theme="dark"] .code-pill{color:#0d1117}
@media (prefers-color-scheme:dark){:root:not([data-theme="light"]) .code-pill{color:#0d1117}}
.filters{display:flex;flex-wrap:wrap;gap:8px;margin:14px 0}
.chip{border:1px solid var(--border);background:var(--surface);color:var(--text);padding:6px 12px;border-radius:999px;cursor:pointer;font:inherit;font-size:.88rem}
.chip[aria-pressed="true"]{background:var(--accent);border-color:var(--accent);color:#fff}
.code-list a{color:var(--text);text-decoration:none}
.code-list a:hover strong{color:var(--accent)}
.empty{padding:24px;text-align:center;color:var(--muted)}

/* Article */
.article{padding:28px 0 20px}
.article p,.article li{max-width:72ch}
.meta{color:var(--muted);font-size:.9rem}
.crumbs{font-size:.88rem;color:var(--muted);margin:22px 0 0}
.crumbs a{color:var(--muted)}
.callout{border-left:4px solid var(--accent);background:var(--accent-soft);padding:12px 16px;border-radius:0 10px 10px 0;margin:18px 0}
.toc{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:14px 18px}
.toc ol{margin:6px 0 0;padding-left:20px}
details{background:var(--surface);border:1px solid var(--border);border-radius:12px;padding:12px 16px;margin-bottom:10px}
summary{cursor:pointer;font-weight:600}

/* Ads: reserved space prevents layout shift (CLS) once AdSense is enabled */
.ad-slot{margin:28px auto;min-height:100px;display:flex;align-items:center;justify-content:center;max-width:970px}
.ad-slot:empty{display:none}
.ad-label{font-size:.7rem;color:var(--muted);text-transform:uppercase;letter-spacing:.08em;text-align:center}

/* Share */
.share{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:24px 0}
.share a,.share button{font-size:.88rem}
.toast{position:fixed;bottom:20px;left:50%;transform:translateX(-50%) translateY(80px);background:var(--text);color:var(--bg);padding:10px 16px;border-radius:10px;transition:transform .25s;z-index:50}
.toast.show{transform:translateX(-50%) translateY(0)}

/* Footer */
.site-footer{margin-top:64px;border-top:1px solid var(--border);padding:36px 0;color:var(--muted);font-size:.92rem}
.foot-grid{display:grid;grid-template-columns:2fr repeat(3,1fr);gap:24px}
@media (max-width:720px){.foot-grid{grid-template-columns:1fr 1fr}}
.site-footer h4{color:var(--text);margin:0 0 8px;font-size:.95rem}
.site-footer ul{list-style:none;padding:0;margin:0}
.site-footer li{margin:4px 0}
.site-footer a{color:var(--muted);text-decoration:none}
.site-footer a:hover{color:var(--accent)}
section{scroll-margin-top:80px}
@media print{.site-header,.site-footer,.ad-slot,.share{display:none}}