:root {
  color-scheme: dark;
  --bg: #0e1621;
  --panel: #17212b;
  --panel-2: #213040;
  --line: #263646;
  --text: #ecf2f8;
  --muted: #8a9aaa;
  --blue: #5288c1;
  --blue-bright: #67b5ff;
  --green: #53d38b;
  --danger: #ff7676;
  font-family: "Segoe UI", Inter, Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  overflow-x: hidden;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at 20% 0%, rgba(82, 136, 193, .18), transparent 34rem),
    radial-gradient(circle at 88% 12%, rgba(83, 211, 139, .10), transparent 32rem),
    var(--bg);
  color: var(--text);
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  height: 76px;
  padding: 0 clamp(20px, 5vw, 72px);
  background: rgba(14, 22, 33, .82);
  border-bottom: 1px solid rgba(138, 154, 170, .16);
  backdrop-filter: blur(18px);
}

.brand,
.nav,
.hero-actions,
footer {
  display: flex;
  align-items: center;
}

.brand {
  gap: 12px;
  font-size: 19px;
  font-weight: 800;
}

.brand img {
  width: 34px;
  height: 34px;
  filter: brightness(1.18) drop-shadow(0 0 10px rgba(103, 181, 255, .18));
}

.nav {
  gap: 26px;
  color: var(--muted);
  font-size: 14px;
}

.nav a:hover {
  color: var(--text);
}

.top-download,
.primary,
.secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 42px;
  border-radius: 12px;
  font-size: 14px;
  font-weight: 800;
}

.top-download,
.primary {
  background: var(--blue);
  color: #fff;
  box-shadow: 0 16px 36px rgba(82, 136, 193, .24);
}

.top-download {
  padding: 0 20px;
}

.primary {
  padding: 0 24px;
}

.secondary {
  padding: 0 22px;
  color: var(--text);
  background: rgba(33, 48, 64, .86);
  border: 1px solid rgba(138, 154, 170, .18);
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(430px, 610px);
  gap: clamp(30px, 5vw, 72px);
  align-items: center;
  min-height: calc(100vh - 120px);
  padding: clamp(36px, 5vw, 68px) clamp(20px, 5vw, 72px);
}

.hero-copy {
  max-width: 670px;
}

h1,
h2,
h3,
p {
  margin: 0;
}

h1 {
  max-width: 720px;
  font-size: clamp(40px, 5vw, 64px);
  line-height: 1.03;
  letter-spacing: 0;
}

.hero-copy p {
  max-width: 610px;
  margin-top: 20px;
  color: var(--muted);
  font-size: 18px;
  line-height: 1.62;
}

.hero-actions {
  gap: 14px;
  margin-top: 28px;
}

.hero-note {
  margin-top: 18px;
  color: #9db2c8;
  font-size: 13px;
}

.product-frame {
  overflow: hidden;
  border: 1px solid rgba(138, 154, 170, .18);
  border-radius: 18px;
  background: #0a111a;
  box-shadow: 0 34px 90px rgba(0, 0, 0, .34);
}

.window-bar {
  display: flex;
  justify-content: flex-end;
  gap: 10px;
  height: 34px;
  padding: 12px 16px;
  background: #223043;
}

.window-bar span {
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: #8da2b8;
}

.app-preview {
  display: grid;
  grid-template-columns: 240px 1fr;
  min-height: 410px;
}

.chat-rail {
  padding: 16px;
  background: var(--panel);
  border-right: 1px solid var(--line);
}

.search,
.composer {
  height: 40px;
  border-radius: 18px;
  background: var(--panel-2);
  color: var(--muted);
  padding: 11px 16px;
  font-size: 13px;
}

.chat {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-top: 14px;
  padding: 10px;
  border-radius: 14px;
}

.chat.active {
  background: rgba(82, 136, 193, .16);
}

.avatar {
  display: grid;
  place-items: center;
  flex: 0 0 auto;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: var(--green);
  color: #07140d;
  font-weight: 900;
}

.avatar.muted {
  background: linear-gradient(135deg, #9fb0c2, #6f7d91);
  color: #fff;
}

.avatar.small {
  width: 42px;
  height: 42px;
}

.chat strong,
.chat-head strong {
  display: block;
  font-size: 14px;
}

.chat p,
.chat-head p {
  margin-top: 4px;
  color: var(--muted);
  font-size: 12px;
}

.conversation {
  position: relative;
  padding: 18px;
  background: #0e1621;
}

.chat-head {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--line);
}

.bubble {
  max-width: 70%;
  margin-top: 24px;
  padding: 13px 16px;
  border-radius: 18px;
  color: #eef6ff;
  font-size: 14px;
  line-height: 1.5;
}

.bubble.left {
  background: #182533;
  border-bottom-left-radius: 6px;
}

.bubble.right {
  margin-left: auto;
  background: #345f8d;
  border-bottom-right-radius: 6px;
}

.call-card {
  width: fit-content;
  margin: 24px auto 0;
  padding: 10px 22px;
  border-radius: 18px;
  background: #213040;
  color: #dceaff;
  font-size: 13px;
  font-weight: 800;
}

.composer {
  position: absolute;
  left: 18px;
  right: 18px;
  bottom: 18px;
}

.band,
.modes,
.security {
  padding: clamp(70px, 9vw, 118px) clamp(20px, 5vw, 72px);
}

.section-title {
  max-width: 760px;
}

h2 {
  font-size: clamp(32px, 4vw, 54px);
  line-height: 1.05;
}

.section-title p,
.security p {
  margin-top: 16px;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.7;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
  margin-top: 36px;
}

.feature-grid article,
.mode-list article {
  border: 1px solid rgba(138, 154, 170, .16);
  border-radius: 18px;
  background: rgba(23, 33, 43, .78);
  padding: 26px;
}

h3 {
  font-size: 20px;
}

.feature-grid p,
.mode-list p {
  margin-top: 12px;
  color: var(--muted);
  line-height: 1.65;
}

.modes {
  background: rgba(8, 13, 20, .35);
}

.mode-list {
  display: grid;
  gap: 16px;
  margin-top: 34px;
}

.mode-list article {
  display: grid;
  grid-template-columns: 54px 160px 1fr;
  align-items: start;
  gap: 22px;
}

.mode-list span {
  color: var(--blue-bright);
  font-weight: 900;
}

.security {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  border-top: 1px solid rgba(138, 154, 170, .12);
  border-bottom: 1px solid rgba(138, 154, 170, .12);
}

.security div {
  max-width: 760px;
}

footer {
  justify-content: space-between;
  padding: 30px clamp(20px, 5vw, 72px);
  color: var(--muted);
  font-size: 13px;
}

@media (max-width: 980px) {
  .nav {
    display: none;
  }

  .hero {
    grid-template-columns: 1fr;
  }

  .product-frame {
    max-width: 680px;
  }

  .feature-grid {
    grid-template-columns: 1fr;
  }

  .mode-list article {
    grid-template-columns: 44px 1fr;
  }

  .mode-list p {
    grid-column: 2;
  }

  .security {
    align-items: flex-start;
    flex-direction: column;
  }
}

@media (max-width: 640px) {
  .topbar {
    height: 66px;
    padding: 0 24px;
  }

  .top-download {
    display: none;
  }

  .hero {
    min-height: auto;
    gap: 32px;
    width: 100vw;
    max-width: 100vw;
    padding: 42px 24px 56px;
  }

  .hero-copy,
  .hero-actions,
  .product-frame {
    width: 100%;
    max-width: 342px;
  }

  h1 {
    font-size: clamp(34px, 10vw, 40px);
    line-height: 1.08;
    overflow-wrap: break-word;
  }

  .hero-copy p {
    font-size: 16px;
    line-height: 1.56;
  }

  .hero-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .primary,
  .secondary {
    width: 100%;
  }

  .app-preview {
    grid-template-columns: 1fr;
    min-height: 360px;
  }

  .chat-rail {
    display: none;
  }

  .product-frame {
    justify-self: start;
    border-radius: 14px;
  }

  .conversation {
    min-width: 0;
    overflow: hidden;
  }

  .bubble {
    max-width: 86%;
  }

  .bubble.right {
    margin-left: 14%;
  }
}

@media (max-width: 420px) {
  h1 {
    font-size: 36px;
  }
}

@media (max-width: 360px) {
  .hero-copy,
  .hero-actions,
  .product-frame {
    max-width: 312px;
  }

  h1 {
    font-size: 32px;
  }
}