/* ФОНГ · связь — public site.
   Tokens follow the ФОНГ design system (tokens/*.css); dark theme is the derived one used in the iOS app. */

:root {
  color-scheme: light dark;

  --bg: #ffffff;
  --bg-muted: #fafafa;
  --surface: #ffffff;
  --surface-2: #fafafa;
  --border: #e4e4e7;
  --border-strong: #d4d4d8;
  --text-strong: #18181b;
  --text-body: #3f3f46;
  --text-muted: #71717a;
  --text-faint: #a1a1aa;
  --accent: #4f46e5;
  --accent-text: #4338ca;
  --accent-surface: #eef2ff;
  --navy: #14142b;
  --danger: #dc2626;
  --btn-primary-bg: #18181b;
  --btn-primary-fg: #ffffff;
  --bubble-mine-bg: #4f46e5;
  --bubble-mine-fg: #ffffff;
  --ring: rgba(79, 70, 229, 0.5);
  --ring-glass: rgba(255, 255, 255, 0.9);

  --font-display: "Unbounded", "Inter Tight", system-ui, sans-serif;
  --font-sans: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, monospace;

  --radius: 10px;
  --radius-xl: 14px;
  --radius-2xl: 18px;
  --radius-full: 999px;
  --container: 1152px;
  --gutter: 24px;

  --shadow-card: 0 1px 2px rgba(20, 20, 43, 0.04), 0 8px 24px rgba(20, 20, 43, 0.06);
  --text-shadow-glass: 0 1px 2px rgba(8, 10, 32, 0.55), 0 6px 28px rgba(8, 10, 32, 0.45);
  --ease-out-expo: cubic-bezier(0.22, 1, 0.36, 1);
  --ease-standard: cubic-bezier(0.4, 0, 0.2, 1);
  --dur-fast: 150ms;
  --dur-enter: 600ms;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0b17;
    --bg-muted: #14142b;
    --surface: #14142b;
    --surface-2: #1a1a33;
    --border: #25253f;
    --border-strong: #33335a;
    --text-strong: #f4f4f5;
    --text-body: #d4d4d8;
    --text-muted: #a1a1aa;
    --text-faint: #8b8b98;
    --accent: #6366f1;
    --accent-text: #a5b4fc;
    --accent-surface: #1e1b4b;
    --danger: #f87171;
    --btn-primary-bg: #f4f4f5;
    --btn-primary-fg: #0b0b17;
    --bubble-mine-bg: #6366f1;
    --ring: rgba(129, 140, 248, 0.6);
  }
}

@media (prefers-reduced-motion: reduce) {
  :root { --dur-fast: 0ms; --dur-enter: 0ms; }
}

/* ---------- base ---------- */

*, *::before, *::after { box-sizing: border-box; }

html {
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
  scroll-behavior: smooth;
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--bg);
  color: var(--text-body);
  font: 400 15px/1.6 var(--font-sans);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

[hidden] { display: none !important; }

img, svg { display: block; max-width: 100%; }

h1, h2, h3 { margin: 0; color: var(--text-strong); font-weight: 500; }

p { margin: 0; }

a { color: var(--accent-text); text-decoration: none; }
a:hover { color: var(--accent); text-decoration: underline; text-underline-offset: 4px; }

button { font: inherit; color: inherit; }

:focus-visible {
  outline: 3px solid var(--ring);
  outline-offset: 2px;
}

code, kbd, samp, .mono { font-family: var(--font-mono); font-size: 0.92em; }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 16px;
  top: 16px;
  z-index: 10;
  padding: 10px 16px;
  border-radius: var(--radius);
  background: var(--btn-primary-bg);
  color: var(--btn-primary-fg);
  font-weight: 500;
  transform: translateY(-200%);
}
.skip-link:focus { transform: none; color: var(--btn-primary-fg); text-decoration: none; }

.wrap {
  width: 100%;
  max-width: calc(var(--container) + 2 * var(--gutter));
  margin: 0 auto;
  padding: 0 var(--gutter);
}

@media (max-width: 640px) {
  :root { --gutter: 16px; }
}

/* ---------- buttons ---------- */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  padding: 0 18px;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font: 500 14px/1.2 var(--font-sans);
  text-align: center;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
  transition:
    background-color var(--dur-fast) var(--ease-standard),
    border-color var(--dur-fast) var(--ease-standard),
    color var(--dur-fast) var(--ease-standard),
    opacity var(--dur-fast) var(--ease-standard);
}
.btn:hover { text-decoration: none; }
.btn:active { transform: translateY(1px); }

.btn--pill { border-radius: var(--radius-full); padding: 0 22px; }

.btn--primary { background: var(--btn-primary-bg); color: var(--btn-primary-fg); }
.btn--primary:hover { color: var(--btn-primary-fg); opacity: 0.8; }

.btn--outline { background: var(--bg); color: var(--text-strong); border-color: var(--border); }
.btn--outline:hover { color: var(--text-strong); border-color: var(--text-strong); }

.btn--glass { background: #ffffff; color: var(--navy); text-shadow: none; }
.btn--glass:hover { color: var(--navy); background: rgba(255, 255, 255, 0.86); }

.btn[data-state="pending"],
.btn[aria-disabled="true"] {
  pointer-events: none;
  cursor: default;
  opacity: 1;
  background: var(--bg-muted);
  color: var(--text-muted);
  border-color: var(--border);
}
.btn--glass[data-state="pending"],
.btn--glass[aria-disabled="true"] {
  background: rgba(255, 255, 255, 0.1);
  color: rgba(255, 255, 255, 0.86);
  border-color: rgba(255, 255, 255, 0.25);
}

/* ---------- hero on glass (12px white frame, radius 10) ---------- */

.hero { padding: 12px; }

.hero__glass {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 56px;
  min-height: clamp(520px, calc(88vh - 24px), 880px);
  min-height: clamp(520px, calc(88svh - 24px), 880px);
  padding: 24px;
  border-radius: var(--radius);
  overflow: hidden;
  color: #ffffff;
  background:
    linear-gradient(to top, rgba(8, 10, 32, 0.62), rgba(8, 10, 32, 0.08) 70%),
    url("glass.jpg") 18% 85% / cover no-repeat #14142b;
}

.hero--compact .hero__glass {
  min-height: 0;
  background:
    linear-gradient(to top, rgba(8, 10, 32, 0.66), rgba(8, 10, 32, 0.3)),
    url("glass.jpg") 18% 85% / cover no-repeat #14142b;
}

.hero__bar {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
}

.brand-pill {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 18px;
  border-radius: var(--radius-full);
  background: #ffffff;
  color: #18181b;
  box-shadow: var(--shadow-card);
  font: 500 17px/1 var(--font-display);
  letter-spacing: -0.02em;
}
.brand-pill:hover { color: #18181b; text-decoration: none; }

.hero__nav ul {
  display: flex;
  margin: 0;
  padding: 4px;
  list-style: none;
  border-radius: var(--radius-full);
  background: #ffffff;
  box-shadow: var(--shadow-card);
}
.hero__nav a {
  display: inline-flex;
  align-items: center;
  min-height: 32px;
  padding: 0 14px;
  border-radius: var(--radius-full);
  color: #18181b;
  font-size: 14px;
  font-weight: 500;
}
.hero__nav a:hover { color: #4338ca; text-decoration: none; }

.hero :focus-visible { outline-color: var(--ring-glass); }

.hero__content {
  max-width: 820px;
  padding: 0 clamp(0px, 4vw, 64px) clamp(8px, 4vh, 48px);
  text-shadow: var(--text-shadow-glass);
  animation: fong-rise var(--dur-enter) var(--ease-out-expo) both;
}

.eyebrow-over {
  margin: 0 0 18px;
  color: rgba(255, 255, 255, 0.74);
  font: 500 11px/1.4 var(--font-sans);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.wordmark {
  margin: 0;
  color: #ffffff;
  font: 500 clamp(64px, 15vw, 168px)/0.95 var(--font-display);
  letter-spacing: -0.025em;
}

.hero__title {
  max-width: 18ch;
  color: #ffffff;
  font: 500 clamp(30px, 5vw, 56px)/1.08 var(--font-display);
  letter-spacing: -0.025em;
  text-wrap: balance;
}

.hero__lead {
  margin-top: 22px;
  max-width: 46ch;
  color: rgba(255, 255, 255, 0.86);
  font-size: clamp(16px, 1.5vw, 19px);
  line-height: 1.55;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px 24px;
  margin-top: 32px;
}

.link-glass { color: rgba(255, 255, 255, 0.92); font-size: 14px; font-weight: 500; }
.link-glass:hover { color: #ffffff; }

@keyframes fong-rise {
  from { opacity: 0; transform: translateY(24px); }
  to { opacity: 1; transform: none; }
}

@media (max-width: 640px) {
  .hero__glass { padding: 16px; gap: 40px; }
  .hero__nav { display: none; }
  .hero__content { padding: 0 4px 8px; }
}

/* ---------- sections ---------- */

.section { padding: 96px 0; border-top: 1px solid var(--border); }
.section--first { border-top: 0; }

@media (max-width: 720px) {
  .section { padding: 64px 0; }
}

.eyebrow {
  margin: 0 0 16px;
  color: var(--text-muted);
  font: 500 14px/1.4 var(--font-sans);
}

.h2 {
  max-width: 24ch;
  font: 500 clamp(26px, 3.6vw, 40px)/1.1 var(--font-display);
  letter-spacing: -0.02em;
  text-wrap: balance;
}

.lead {
  margin-top: 20px;
  max-width: 58ch;
  color: var(--text-muted);
  font-size: 18px;
  line-height: 1.6;
}

@media (max-width: 640px) {
  .lead { font-size: 16px; }
}

/* message path diagram: sender -> server -> recipient */

.flow { margin: 48px 0 0; }

.flow__grid {
  display: grid;
  grid-template-columns: 1fr 1.25fr 1fr;
  gap: 1px;
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  background: var(--border);
}

.flow__cell {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 16px;
  min-width: 0;
  padding: 28px;
  background: var(--surface);
}
.flow__cell:first-child { border-radius: var(--radius-2xl) 0 0 var(--radius-2xl); }
.flow__cell:last-child { border-radius: 0 var(--radius-2xl) var(--radius-2xl) 0; }
.flow__cell--server { background: var(--surface-2); }

.flow__cell + .flow__cell::before {
  content: "→";
  position: absolute;
  z-index: 1;
  top: 50%;
  left: -13px;
  display: grid;
  place-items: center;
  width: 26px;
  height: 26px;
  margin-top: -13px;
  border: 1px solid var(--border);
  border-radius: var(--radius-full);
  background: var(--bg);
  color: var(--text-muted);
  font: 400 13px/1 var(--font-sans);
}

.flow__label { color: var(--text-muted); font-size: 13px; font-weight: 500; }

.flow__bubble {
  align-self: flex-start;
  max-width: 100%;
  padding: 10px 14px;
  border-radius: 18px;
  font-size: 16px;
  line-height: 1.4;
}
.flow__bubble--mine { align-self: flex-end; background: var(--bubble-mine-bg); color: var(--bubble-mine-fg); border-bottom-right-radius: 6px; }
.flow__bubble--theirs { background: var(--bg); color: var(--text-strong); border: 1px solid var(--border); border-bottom-left-radius: 6px; }

.flow__cipher {
  display: grid;
  gap: 8px;
  margin: 0;
  color: var(--text-strong);
  font: 400 13px/1.5 var(--font-mono);
}
.flow__cipher div { display: grid; grid-template-columns: 28px 1fr; gap: 8px; }
.flow__cipher dt { color: var(--text-muted); }
.flow__cipher dd { margin: 0; overflow-wrap: anywhere; }

.flow__note { margin-top: auto; color: var(--text-muted); font-size: 13px; line-height: 1.5; }

.flow figcaption {
  margin-top: 16px;
  max-width: 72ch;
  color: var(--text-muted);
  font-size: 14px;
}

@media (max-width: 860px) {
  .flow__grid { grid-template-columns: 1fr; }
  .flow__cell { padding: 24px 20px; }
  .flow__cell:first-child { border-radius: var(--radius-2xl) var(--radius-2xl) 0 0; }
  .flow__cell:last-child { border-radius: 0 0 var(--radius-2xl) var(--radius-2xl); }
  .flow__cell + .flow__cell::before {
    content: "↓";
    top: -13px;
    left: 50%;
    margin: 0 0 0 -13px;
  }
}

/* three statements under the diagram */

.points {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 32px;
  margin: 56px 0 0;
  padding: 0;
  list-style: none;
}
.points li { padding-top: 20px; border-top: 1px solid var(--border-strong); }
.points h3 { font-size: 16px; font-weight: 600; line-height: 1.35; }
.points p { margin-top: 10px; color: var(--text-muted); font-size: 15px; }

@media (max-width: 860px) {
  .points { grid-template-columns: 1fr; gap: 28px; margin-top: 40px; }
}

/* numbered steps (a real sequence) */

.steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  margin: 48px 0 0;
  padding: 0;
  list-style: none;
  border: 1px solid var(--border);
  border-radius: var(--radius-2xl);
  background: var(--border);
  overflow: hidden;
}

.step {
  display: flex;
  flex-direction: column;
  gap: 10px;
  min-width: 0;
  padding: 28px;
  background: var(--surface);
}

.step__num { color: var(--text-faint); font: 500 13px/1 var(--font-mono); }
.step__title { margin-top: 6px; font-size: 17px; font-weight: 600; line-height: 1.35; }
.step p { color: var(--text-muted); }
.step .btn { align-self: flex-start; margin-top: auto; }
.step p + .btn { margin-top: 12px; }

@media (max-width: 860px) {
  .steps { grid-template-columns: 1fr; }
  .step { padding: 24px 20px; }
}

.note {
  margin-top: 24px;
  max-width: 72ch;
  color: var(--text-muted);
  font-size: 14px;
}

.card {
  margin-top: 24px;
  padding: 20px 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  background: var(--surface);
  color: var(--text-body);
}

/* two-column block */

.split {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 24px 64px;
  align-items: start;
}
.split__body p { color: var(--text-muted); font-size: 16px; }
.split__body p + p { margin-top: 12px; }
.split__body .btn { margin-top: 24px; }

@media (max-width: 860px) {
  .split { grid-template-columns: 1fr; }
}

/* ---------- footer ---------- */

.footer {
  padding: 32px 0 40px;
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 14px;
}

.footer__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px 40px;
}

.footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 24px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer a {
  display: inline-block;
  padding: 4px 0;
  color: var(--text-muted);
}
.footer a:hover { color: var(--text-strong); }

.footer__contact { display: flex; flex-wrap: wrap; align-items: baseline; gap: 0 16px; }
.footer__operator { flex-basis: 100%; margin: 0; }

/* ---------- invite page ---------- */

.invite-code { margin-top: 32px; }

.invite-code__label {
  color: rgba(255, 255, 255, 0.74);
  font: 500 11px/1.4 var(--font-sans);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.invite-code__value {
  margin: 10px 0 22px;
  color: #ffffff;
  font: 500 clamp(40px, 12vw, 84px)/1 var(--font-mono);
  letter-spacing: 0.04em;
  font-variant-numeric: tabular-nums;
  -webkit-user-select: all;
  user-select: all;
}

.copy-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 20px;
}

.copy-status {
  min-height: 1.4em;
  color: rgba(255, 255, 255, 0.9);
  font-size: 14px;
}

.glass-note {
  margin-top: 28px;
  max-width: 52ch;
  padding: 16px 20px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  border-radius: var(--radius-xl);
  background: rgba(255, 255, 255, 0.1);
  color: #ffffff;
  font-size: 15px;
  text-shadow: none;
}

.step__alt { color: var(--text-muted); }

/* ---------- document pages (privacy, terms) ---------- */

.topbar { border-bottom: 1px solid var(--border); }

.topbar__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 24px;
  min-height: 64px;
  padding-top: 10px;
  padding-bottom: 10px;
}

.brand {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  color: var(--text-strong);
  font: 500 18px/1 var(--font-display);
  letter-spacing: -0.02em;
}
.brand:hover { color: var(--text-strong); text-decoration: none; }
.brand__sub { color: var(--text-muted); font: 500 15px/1 var(--font-sans); letter-spacing: 0; }

.topbar__nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 4px 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.topbar__nav a { display: inline-block; padding: 6px 0; color: var(--text-muted); font-size: 14px; font-weight: 500; }
.topbar__nav a:hover { color: var(--text-strong); }
.topbar__nav a[aria-current="page"] { color: var(--text-strong); }

.doc { padding: 56px 0 96px; }

.doc__head { max-width: 760px; }

.doc__title {
  /* «конфиденциальности» is ~14em wide in Unbounded: size it so the word fits a 320 px screen */
  font: 500 clamp(20px, calc((100vw - 32px) / 14.2), 44px)/1.1 var(--font-display);
  letter-spacing: -0.02em;
  text-wrap: balance;
  overflow-wrap: break-word;
}

.doc__meta {
  margin-top: 16px;
  color: var(--text-muted);
  font: 400 13px/1.6 var(--font-mono);
}

.doc__body { max-width: 760px; }
.doc__body > p, .doc__body > ul, .doc__body > ol { max-width: 68ch; }
.doc__body p { margin-top: 12px; }
.doc__body ul, .doc__body ol { margin: 12px 0 0; padding-left: 1.3em; }
.doc__body li + li { margin-top: 6px; }
.doc__body li::marker { color: var(--text-faint); }
.doc__body strong { color: var(--text-strong); font-weight: 600; }

.doc__body h2 {
  margin-top: 56px;
  scroll-margin-top: 24px;
  font: 500 21px/1.25 var(--font-display);
  letter-spacing: -0.02em;
}
.doc__body h3 {
  margin-top: 28px;
  font: 600 15px/1.4 var(--font-sans);
}

.doc__lead { margin-top: 24px; max-width: 64ch; color: var(--text-body); font-size: 17px; }

.toc {
  margin-top: 32px;
  padding: 20px 24px;
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
}
.toc__title { color: var(--text-muted); font-size: 13px; font-weight: 500; }
.toc ol {
  columns: 2;
  column-gap: 32px;
  margin: 10px 0 0;
  padding-left: 1.4em;
  font-size: 14px;
}
.toc li { break-inside: avoid; }
.toc li + li { margin-top: 4px; }
.toc li::marker { color: var(--text-faint); font-family: var(--font-mono); font-size: 12px; }

@media (max-width: 640px) {
  .toc ol { columns: 1; }
}

.callout {
  margin-top: 32px;
  padding: 20px 24px;
  border-radius: var(--radius-xl);
  background: var(--accent-surface);
  color: var(--text-strong);
}
.callout ul { margin: 0; padding-left: 1.2em; }
.callout li + li { margin-top: 8px; }
.callout li::marker { color: var(--accent-text); }

.data-table {
  width: 100%;
  margin-top: 20px;
  border-collapse: collapse;
  font-size: 14px;
  line-height: 1.5;
}
.data-table th {
  padding: 0 16px 10px 0;
  border-bottom: 1px solid var(--border-strong);
  color: var(--text-muted);
  font-weight: 500;
  text-align: left;
  vertical-align: bottom;
}
.data-table td {
  padding: 12px 16px 12px 0;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
.data-table td:first-child { color: var(--text-strong); font-weight: 500; }
.data-table th:last-child, .data-table td:last-child { padding-right: 0; }

@media (max-width: 640px) {
  .data-table thead {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
  }
  .data-table tr { display: block; padding: 14px 0; border-bottom: 1px solid var(--border); }
  .data-table td { display: block; padding: 2px 0; border: 0; }
  .data-table td + td { margin-top: 8px; }
  .data-table td[data-label]::before {
    content: attr(data-label);
    display: block;
    color: var(--text-muted);
    font-size: 12px;
    font-weight: 500;
  }
}

@media print {
  .skip-link, .topbar__nav, .footer { display: none; }
  .doc { padding: 0; }
  body { background: #ffffff; color: #000000; }
}