/* Dialtone Technologies design system (brand guidelines, 2 Oct 2026).
   Palette 60/30/10: Cloud White surfaces, Slate Ink + Deep Navy structure, Signal Blue + Quantum Cyan accents.
   Type: Manrope (headings 600/700), Inter (body 400-600), 1.25 scale on a 16px base. Spacing: 4px unit.
   Shape: 12px buttons and inputs, 18px cards, pill badges. Depth: soft shadows only. */

:root {
    --navy: #0F172A;
    --signal: #3B82F6;
    --cyan: #06B6D4;
    --violet: #7C3AED;
    --cloud: #F8FAFC;
    --white: #FFFFFF;
    --ink: #1E293B;

    --bg: var(--cloud);
    --surface: var(--white);
    --surface-muted: #EBECEF;
    --text: var(--ink);
    --text-muted: #656D81;
    --border: #E2E8F0;
    --primary: var(--navy);
    --primary-text: #F8FAFC;
    --link: #1D4ED8;
    --success: #16A34A;

    --font-heading: "Manrope", "Inter", system-ui, sans-serif;
    --font-body: "Inter", system-ui, sans-serif;
    --font-mono: "JetBrains Mono", "Cascadia Code", Consolas, monospace;

    --step-5xl: 3.815rem;  /* 61px display */
    --step-4xl: 3.052rem;  /* 48.8px */
    --step-3xl: 2.441rem;  /* 39.1px */
    --step-2xl: 1.953rem;  /* 31.2px */
    --step-xl: 1.563rem;   /* 25px */
    --step-lg: 1.25rem;    /* 20px */
    --step-sm: 0.8rem;     /* 12.8px */

    --radius-control: 12px;
    --radius-card: 18px;
    --shadow-soft: 0 1px 2px rgba(15, 23, 42, .04), 0 8px 24px rgba(15, 23, 42, .06);
    --shadow-lift: 0 2px 4px rgba(15, 23, 42, .05), 0 16px 40px rgba(15, 23, 42, .10);
    --container: 1200px;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg: #1E2025;
        --surface: #1E293B;
        --surface-muted: #414653;
        --text: #F7F7F8;
        --text-muted: #94A3B8;
        --border: #535A6A;
        --primary: #7992CE;
        --primary-text: #0F172A;
        --link: #93C5FD;
        --shadow-soft: 0 1px 2px rgba(0, 0, 0, .3), 0 8px 24px rgba(0, 0, 0, .25);
        --shadow-lift: 0 2px 4px rgba(0, 0, 0, .3), 0 16px 40px rgba(0, 0, 0, .35);
    }
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
body {
    margin: 0;
    background: var(--bg);
    color: var(--text);
    font: 400 1rem/1.65 var(--font-body);
    -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--link); text-underline-offset: 3px; }
a:hover { text-decoration-thickness: 2px; }
:focus-visible { outline: 3px solid var(--signal); outline-offset: 3px; border-radius: 4px; }
/* FocusOnNavigate (Routes.razor) focuses the page heading after each navigation so screen readers announce the page.
   The heading is not interactive, so it gets no focus ring. */
h1:focus, h1:focus-visible { outline: none; }

h1, h2, h3, h4 { font-family: var(--font-heading); color: var(--text); margin: 0 0 16px; line-height: 1.15; letter-spacing: -0.015em; }
h1 { font-size: var(--step-4xl); font-weight: 700; }
h2 { font-size: var(--step-3xl); font-weight: 700; }
h3 { font-size: var(--step-xl); font-weight: 600; }
h4 { font-size: var(--step-lg); font-weight: 600; }
p { margin: 0 0 16px; max-width: 68ch; }
.muted { color: var(--text-muted); }
code { font-family: var(--font-mono); font-size: .9em; }
p code, li code, td code { background: var(--surface-muted); padding: 2px 6px; border-radius: 6px; }

.container { width: 100%; max-width: var(--container); margin: 0 auto; padding: 0 24px; }
.section { padding: 96px 0; }
.section-tight { padding: 64px 0; }
.section-alt { background: var(--surface); border-block: 1px solid var(--border); }
.section-head { max-width: 760px; margin-bottom: 48px; }
.section-head.center { margin-inline: auto; text-align: center; }
.section-head.center p { margin-inline: auto; }
.lead { font-size: var(--step-lg); color: var(--text-muted); line-height: 1.6; }

.eyebrow {
    display: inline-flex; align-items: center; gap: 8px; margin-bottom: 16px;
    font: 600 var(--step-sm)/1 var(--font-body); letter-spacing: .12em; text-transform: uppercase; color: var(--text-muted);
}
.eyebrow::before { content: ""; width: 8px; height: 8px; border-radius: 50%; background: var(--cyan); box-shadow: 0 0 0 4px rgba(6, 182, 212, .18); }

.skip-link { position: absolute; left: -999px; top: 8px; z-index: 100; background: var(--navy); color: #fff; padding: 8px 16px; border-radius: 8px; }
.skip-link:focus { left: 8px; }

/* Buttons: 12px radius, weight 600, sentence case */
.btn {
    display: inline-flex; align-items: center; justify-content: center; gap: 8px;
    padding: 12px 20px; border-radius: var(--radius-control); border: 1px solid transparent;
    font: 600 1rem/1.2 var(--font-body); text-decoration: none; cursor: pointer;
    transition: background-color .15s, border-color .15s, color .15s, transform .15s;
}
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn-sm { padding: 8px 16px; font-size: .9375rem; }
.btn-lg { padding: 16px 24px; font-size: var(--step-lg); }
.btn-primary { background: var(--primary); color: var(--primary-text); }
.btn-primary:hover { background: #1E293B; color: #fff; }
.btn-signal { background: var(--signal); color: #fff; }
.btn-signal:hover { background: #2563EB; }
.btn-outline { background: transparent; color: var(--text); border-color: var(--border); }
.btn-outline:hover { border-color: var(--signal); color: var(--signal); }
.btn-ghost-light { background: rgba(248, 250, 252, .08); color: #F8FAFC; border-color: rgba(248, 250, 252, .24); }
.btn-ghost-light:hover { background: rgba(248, 250, 252, .14); }
@media (prefers-color-scheme: dark) { .btn-primary:hover { background: #A5B6E0; color: #0F172A; } }

.badge {
    display: inline-flex; align-items: center; gap: 8px; padding: 4px 12px; border-radius: 999px;
    font: 600 var(--step-sm)/1.5 var(--font-body); background: rgba(59, 130, 246, .12); color: var(--link);
}
.badge-cyan { background: rgba(6, 182, 212, .14); color: #0E7490; }
@media (prefers-color-scheme: dark) { .badge-cyan { color: #67E8F9; } }

/* Header */
.site-header {
    position: sticky; top: 0; z-index: 50;
    background: color-mix(in srgb, var(--bg) 88%, transparent);
    backdrop-filter: saturate(160%) blur(12px);
    border-bottom: 1px solid var(--border);
}
.header-inner { display: flex; align-items: center; gap: 24px; height: 72px; }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; color: var(--text); }
.brand img { height: 36px; width: auto; }
.brand-product {
    font: 700 1.125rem/1 var(--font-heading); padding-left: 12px; border-left: 1px solid var(--border); letter-spacing: -.01em;
}
@media (prefers-color-scheme: dark) { .brand img { content: url("img/dialtone-logo-light.png"); } }
.site-nav { margin-left: auto; display: flex; align-items: center; gap: 4px; }
.site-nav a:not(.btn) {
    color: var(--text); text-decoration: none; font-weight: 500; padding: 8px 12px; border-radius: 10px;
}
.site-nav a:not(.btn):hover { background: var(--surface-muted); }
.site-nav a.active { color: var(--link); background: rgba(59, 130, 246, .10); }
.site-nav .btn { margin-left: 8px; }
.nav-toggle, .nav-toggle-label { display: none; }

@media (max-width: 880px) {
    .nav-toggle-label {
        display: flex; margin-left: auto; width: 44px; height: 44px; align-items: center; justify-content: center;
        border-radius: 10px; cursor: pointer;
    }
    .nav-toggle-label span, .nav-toggle-label span::before, .nav-toggle-label span::after {
        display: block; width: 20px; height: 2px; background: var(--text); border-radius: 2px; position: relative; content: "";
    }
    .nav-toggle-label span::before { position: absolute; top: -6px; }
    .nav-toggle-label span::after { position: absolute; top: 6px; }
    .site-nav {
        display: none; position: absolute; top: 72px; left: 0; right: 0; flex-direction: column; align-items: stretch;
        padding: 16px 24px 24px; background: var(--bg); border-bottom: 1px solid var(--border); box-shadow: var(--shadow-soft);
    }
    .site-nav .btn { margin: 8px 0 0; }
    .nav-toggle:checked ~ .site-nav { display: flex; }
}

/* Hero (Deep Navy anchor) */
.hero {
    position: relative; overflow: hidden; color: #E2E8F0; background: var(--navy);
    padding: 112px 0 96px;
}
.hero::before {
    content: ""; position: absolute; inset: 0; pointer-events: none;
    background:
        radial-gradient(600px 300px at 85% 10%, rgba(59, 130, 246, .28), transparent 70%),
        radial-gradient(500px 280px at 10% 90%, rgba(6, 182, 212, .14), transparent 70%);
}
.hero::after {
    content: ""; position: absolute; inset: 0; pointer-events: none; opacity: .35;
    background-image: linear-gradient(rgba(148, 163, 184, .08) 1px, transparent 1px), linear-gradient(90deg, rgba(148, 163, 184, .08) 1px, transparent 1px);
    background-size: 48px 48px;
    mask-image: radial-gradient(ellipse at 70% 30%, #000 30%, transparent 75%);
}
.hero .container { position: relative; z-index: 1; }
.hero h1 { color: #F8FAFC; font-size: var(--step-5xl); max-width: 16ch; line-height: 1.05; text-wrap: balance; }
.hero h1 .accent { color: #67E8F9; }
.hero .lead { color: #CBD5E1; max-width: 56ch; }
.hero .eyebrow { color: #94A3B8; }
.hero-grid { display: grid; grid-template-columns: 1.05fr 1fr; gap: 56px; align-items: center; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin: 32px 0 24px; }
.hero-meta { display: flex; flex-wrap: wrap; gap: 8px 24px; color: #94A3B8; font-size: .9375rem; padding: 0; margin: 0; list-style: none; }
.hero-meta li { display: flex; align-items: center; gap: 8px; }
.hero-meta .icon { color: var(--cyan); }
.page-hero { padding: 88px 0 72px; }
.page-hero h1 { font-size: var(--step-4xl); max-width: 20ch; }

/* Cards: 18px radius, soft shadow, elevated = primary content */
.card {
    background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius-card);
    padding: 28px; box-shadow: var(--shadow-soft);
}
.card h3 { font-size: var(--step-lg); margin-bottom: 8px; }
.card p { color: var(--text-muted); margin: 0; }
.card-link { display: block; text-decoration: none; color: inherit; transition: transform .2s, box-shadow .2s, border-color .2s; }
.card-link:hover { transform: translateY(-2px); box-shadow: var(--shadow-lift); border-color: rgba(59, 130, 246, .5); }
.card-flat { box-shadow: none; background: transparent; }
.icon-tile {
    width: 48px; height: 48px; border-radius: 14px; display: grid; place-items: center; margin-bottom: 20px;
    background: rgba(59, 130, 246, .10); color: var(--signal);
}
.icon-tile.cyan { background: rgba(6, 182, 212, .12); color: #0891B2; }
.icon-tile.violet { background: rgba(124, 58, 237, .10); color: var(--violet); }
@media (prefers-color-scheme: dark) { .icon-tile.cyan { color: #22D3EE; } .icon-tile.violet { color: #A78BFA; } }

.grid { display: grid; gap: 24px; }
.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

/* Track cards (servers / softphones) */
.track { padding: 36px; display: flex; flex-direction: column; gap: 16px; }
.track h3 { font-size: var(--step-2xl); margin: 0; }
.track ul { margin: 4px 0 8px; padding: 0; list-style: none; display: grid; gap: 8px; }
.track li { display: flex; gap: 12px; align-items: flex-start; }
.track li .icon { color: var(--success); flex: none; margin-top: 3px; }
.track .more { margin-top: auto; font-weight: 600; display: inline-flex; align-items: center; gap: 8px; color: var(--link); }

/* Stats strip */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; }
.stat { padding: 24px 28px; border-left: 1px solid var(--border); }
.stat:first-child { border-left: none; }
.stat strong { display: block; font: 700 var(--step-2xl)/1.1 var(--font-heading); color: var(--text); margin-bottom: 4px; }
.stat span { color: var(--text-muted); font-size: .9375rem; }

/* Feature list */
.feature { display: flex; gap: 20px; }
.feature .icon-tile { flex: none; margin: 0; }
.feature h3 { font-size: var(--step-lg); margin: 4px 0 6px; }
.feature p { color: var(--text-muted); margin: 0; }

.checklist { list-style: none; padding: 0; margin: 0; display: grid; gap: 12px; }
.checklist li { display: flex; gap: 12px; align-items: flex-start; }
.checklist .icon { color: var(--success); flex: none; margin-top: 3px; }

/* Code blocks: always dark, like an editor */
.code-block {
    margin: 0; border-radius: var(--radius-card); overflow: hidden; background: #0B1220;
    border: 1px solid rgba(148, 163, 184, .18); box-shadow: 0 24px 60px rgba(2, 6, 23, .35);
}
.code-head {
    display: flex; align-items: center; gap: 12px; padding: 12px 16px;
    background: #111A2E; border-bottom: 1px solid rgba(148, 163, 184, .14);
}
.code-dots { display: flex; gap: 6px; }
.code-dots i { width: 10px; height: 10px; border-radius: 50%; background: #334155; display: block; }
.code-title { font: 500 .8125rem/1 var(--font-mono); color: #94A3B8; }
.code-copy {
    margin-left: auto; background: transparent; color: #94A3B8; border: 1px solid rgba(148, 163, 184, .28);
    border-radius: 8px; padding: 4px 10px; font: 500 .75rem/1.2 var(--font-body); cursor: pointer;
}
.code-copy:hover { color: #F8FAFC; border-color: #94A3B8; }
.code-block pre {
    margin: 0; padding: 20px 24px; overflow-x: auto; color: #E2E8F0;
    font: 400 .875rem/1.7 var(--font-mono); tab-size: 4;
}
.hero .code-block pre, .split .code-block pre { font-size: .8125rem; }
.tok-keyword { color: #93C5FD; }
.tok-type { color: #67E8F9; }
.tok-method { color: #C4B5FD; }
.tok-string { color: #86EFAC; }
.tok-key { color: #93C5FD; }
.tok-number { color: #FDBA74; }
.tok-comment { color: #64748B; font-style: italic; }

/* CSS-only tabs */
.tabs { display: grid; gap: 16px; }
.tabs > input { position: absolute; opacity: 0; pointer-events: none; }
.tab-list { display: flex; flex-wrap: wrap; gap: 8px; }
.tab-list label {
    padding: 8px 16px; border-radius: 999px; border: 1px solid var(--border); cursor: pointer; font-weight: 600;
    color: var(--text-muted); background: var(--surface); transition: all .15s;
}
.tab-panel { display: none; }
#tab-client:checked ~ .tab-list label[for="tab-client"],
#tab-ivr:checked ~ .tab-list label[for="tab-ivr"],
#tab-server:checked ~ .tab-list label[for="tab-server"],
#tab-softphone:checked ~ .tab-list label[for="tab-softphone"] { background: var(--primary); color: var(--primary-text); border-color: var(--primary); }
#tab-client:checked ~ .panel-client,
#tab-ivr:checked ~ .panel-ivr,
#tab-server:checked ~ .panel-server,
#tab-softphone:checked ~ .panel-softphone { display: block; }
.tabs > input:focus-visible ~ .tab-list label { outline: none; }
.tabs > input:focus-visible + .tab-list label { box-shadow: 0 0 0 3px rgba(59, 130, 246, .5); }

/* Split layouts */
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 64px; align-items: center; }
.split.wide-left { grid-template-columns: 1.1fr .9fr; }

/* Architecture diagram */
.arch { display: grid; gap: 12px; }
.arch-row { display: grid; gap: 12px; }
.arch-box {
    border-radius: 14px; padding: 16px 20px; border: 1px solid var(--border); background: var(--surface);
    box-shadow: var(--shadow-soft);
}
.arch-box strong { display: block; font-family: var(--font-heading); font-size: 1.0625rem; }
.arch-box span { color: var(--text-muted); font-size: .875rem; }
.arch-box.app { background: var(--navy); border-color: var(--navy); }
.arch-box.app strong { color: #F8FAFC; } .arch-box.app span { color: #94A3B8; }
.arch-box.core { border: 2px solid var(--signal); background: rgba(59, 130, 246, .06); }
.arch-box.code { font-family: var(--font-mono); }
.arch-arrow { text-align: center; color: var(--text-muted); font-size: .8125rem; letter-spacing: .08em; text-transform: uppercase; }
.arch-adapters { grid-template-columns: repeat(3, 1fr); }

/* Product shot */
.shot {
    border-radius: var(--radius-card); overflow: hidden; border: 1px solid rgba(148, 163, 184, .25);
    box-shadow: 0 30px 80px rgba(2, 6, 23, .35);
}

/* Tables */
.spec-table { width: 100%; border-collapse: collapse; background: var(--surface); border-radius: var(--radius-card); overflow: hidden; box-shadow: var(--shadow-soft); border: 1px solid var(--border); }
.spec-table th, .spec-table td { text-align: left; padding: 16px 20px; border-bottom: 1px solid var(--border); vertical-align: top; }
.spec-table th { width: 30%; font-family: var(--font-heading); font-weight: 600; color: var(--text); }
.spec-table td { color: var(--text-muted); }
.spec-table tr:last-child th, .spec-table tr:last-child td { border-bottom: none; }

/* Licensing */
.licence-dims { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
.licence-dim { padding: 32px; }
.licence-dim .big { font: 700 var(--step-3xl)/1 var(--font-heading); color: var(--text); margin: 8px 0 12px; display: block; }
.steps { counter-reset: step; display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; list-style: none; padding: 0; margin: 0; }
.steps li { counter-increment: step; position: relative; padding-top: 56px; }
.steps li::before {
    content: counter(step); position: absolute; top: 0; left: 0; width: 40px; height: 40px; border-radius: 12px;
    display: grid; place-items: center; font: 700 1.125rem/1 var(--font-heading); background: var(--primary); color: var(--primary-text);
}
.faq details { border-bottom: 1px solid var(--border); padding: 20px 0; }
.faq summary { cursor: pointer; font: 600 var(--step-lg)/1.4 var(--font-heading); list-style: none; display: flex; justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--signal); font-weight: 700; }
.faq details[open] summary::after { content: "−"; }
.faq details p { margin: 12px 0 0; color: var(--text-muted); }

/* Forms: 12px radius, 1px border, outlined */
.form-card { padding: 40px; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.field { display: grid; gap: 8px; }
.field.full { grid-column: 1 / -1; }
.field label { font-weight: 600; font-size: .9375rem; }
.field .hint { font-size: var(--step-sm); color: var(--text-muted); }
.field input, .field select, .field textarea {
    width: 100%; padding: 12px 14px; border-radius: var(--radius-control); border: 1px solid var(--border);
    background: var(--bg); color: var(--text); font: 400 1rem/1.4 var(--font-body);
}
.field textarea { min-height: 112px; resize: vertical; }
.field input:focus, .field select:focus, .field textarea:focus { outline: none; border-color: var(--signal); box-shadow: 0 0 0 3px rgba(59, 130, 246, .2); }
.field .validation-message, .validation-errors { color: #DC2626; font-size: .875rem; }
.validation-errors { margin: 0 0 16px; padding-left: 20px; }
.invalid { border-color: #DC2626 !important; }
.form-actions { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; margin-top: 28px; }
.summary-box { border-radius: 14px; background: var(--bg); border: 1px dashed var(--border); padding: 20px 24px; }
.summary-box dl { display: grid; grid-template-columns: auto 1fr; gap: 8px 24px; margin: 0; }
.summary-box dt { color: var(--text-muted); }
.summary-box dd { margin: 0; font-weight: 600; }
.alert-success { border-radius: 14px; padding: 16px 20px; background: rgba(22, 163, 74, .10); color: var(--text); border: 1px solid rgba(22, 163, 74, .3); }

/* CTA band */
.cta-band { background: var(--navy); color: #CBD5E1; border-radius: 24px; padding: 64px; position: relative; overflow: hidden; }
.cta-band::before { content: ""; position: absolute; inset: 0; background: radial-gradient(500px 240px at 90% 0%, rgba(59, 130, 246, .35), transparent 70%); }
.cta-band > * { position: relative; }
.cta-band h2 { color: #F8FAFC; max-width: 20ch; }
.cta-band p { color: #CBD5E1; }
.cta-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 24px; }

/* Footer */
.site-footer { background: var(--navy); color: #94A3B8; padding: 64px 0 32px; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 48px; }
.footer-grid a { display: block; color: #CBD5E1; text-decoration: none; padding: 4px 0; }
.footer-grid a:hover { color: #F8FAFC; }
.footer-brand img { height: 44px; width: auto; margin-bottom: 16px; }
.footer-brand p { color: #CBD5E1; max-width: 46ch; }
.site-footer .muted { color: #94A3B8; }
.footer-title { font: 600 .8125rem/1 var(--font-body); color: #F8FAFC; text-transform: uppercase; letter-spacing: .12em; margin-bottom: 16px; }
.footer-legal { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 12px; margin-top: 48px; padding-top: 24px; border-top: 1px solid rgba(148, 163, 184, .2); font-size: var(--step-sm); }

/* Responsive */
@media (max-width: 1024px) {
    .hero-grid, .split, .split.wide-left { grid-template-columns: 1fr; gap: 48px; }
    .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
    .stats { grid-template-columns: repeat(2, 1fr); }
    .stat:nth-child(3) { border-left: none; }
}
@media (max-width: 720px) {
    .section { padding: 64px 0; }
    .hero { padding: 72px 0 64px; }
    .hero h1 { font-size: var(--step-3xl); }
    .page-hero h1, h1 { font-size: var(--step-3xl); }
    h2 { font-size: var(--step-2xl); }
    .grid-2, .grid-3, .grid-4, .licence-dims, .steps, .form-grid, .footer-grid { grid-template-columns: 1fr; }
    .arch-adapters { grid-template-columns: 1fr; }
    .stats { grid-template-columns: 1fr; }
    .stat { border-left: none; border-top: 1px solid var(--border); }
    .stat:first-child { border-top: none; }
    .cta-band, .form-card { padding: 32px 24px; }
    .container { padding: 0 16px; }
    .code-block pre { font-size: .8125rem; padding: 16px; }
}
@media (prefers-reduced-motion: reduce) { * { transition: none !important; scroll-behavior: auto !important; } }