/* ============================================================
   VoiceSift — Marketing single page
   Western SaaS aesthetic: dark hero + light body
   ============================================================ */

:root {
  --bg: #ffffff;
  --bg-soft: #f7f8fa;
  --ink: #0e1116;
  --ink-2: #3d4450;
  --ink-3: #6b7280;
  --line: #e6e8ec;
  --dark: #0a0d14;
  --dark-2: #11151f;
  --dark-line: rgba(255, 255, 255, 0.08);
  --dark-ink: #eef1f6;
  --dark-ink-2: #9aa3b2;
  --accent: #6366f1;
  --accent-2: #8b5cf6;
  --grad: linear-gradient(135deg, #6366f1 0%, #8b5cf6 50%, #d946ef 100%);
  --radius: 16px;
  --shadow-card: 0 1px 2px rgba(14, 17, 22, 0.04), 0 8px 24px rgba(14, 17, 22, 0.06);
  --shadow-pop: 0 24px 64px rgba(14, 17, 22, 0.16);
  --font: "Inter", -apple-system, "Segoe UI", "PingFang SC", "Hiragino Sans", "Noto Sans CJK SC", "Malgun Gothic", "Microsoft YaHei", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

.container { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  font-family: inherit; font-weight: 600; text-decoration: none;
  border-radius: 12px; border: none; cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease, background 0.15s ease;
  white-space: nowrap;
}
.btn-primary {
  background: linear-gradient(135deg, #6366f1, #8b5cf6);
  color: #fff;
  box-shadow: 0 4px 16px rgba(99, 102, 241, 0.35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(99, 102, 241, 0.45); }
.btn-ghost {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid rgba(255, 255, 255, 0.18);
  color: #fff;
}
.btn-ghost:hover { background: rgba(255, 255, 255, 0.12); border-color: rgba(255, 255, 255, 0.3); transform: translateY(-2px); }
.btn-lg { padding: 14px 32px; font-size: 16px; }
.btn-sm { padding: 9px 18px; font-size: 14px; }

/* ---------- Nav ---------- */
.nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(10, 13, 20, 0.72);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--dark-line);
}
.nav-inner { display: flex; align-items: center; gap: 32px; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.brand-logo { width: 30px; height: 30px; border-radius: 8px; }
.brand-logo.sm { width: 24px; height: 24px; }
.brand-name { font-weight: 700; font-size: 17px; color: #fff; letter-spacing: -0.01em; }
.nav-links { display: flex; gap: 28px; flex: 1; }
.nav-links a {
  color: var(--dark-ink-2); text-decoration: none; font-size: 14px; font-weight: 500;
  transition: color 0.15s;
}
.nav-links a:hover { color: #fff; }
.nav-actions { display: flex; align-items: center; gap: 12px; }

/* Language switch */
.lang-switch { position: relative; }
.lang-btn {
  display: flex; align-items: center; gap: 8px;
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--dark-line);
  color: #fff; font-family: inherit; font-size: 13px; font-weight: 500;
  padding: 8px 12px; border-radius: 10px; cursor: pointer;
  transition: background 0.15s;
}
.lang-btn:hover { background: rgba(255, 255, 255, 0.12); }
.lang-flag { font-size: 15px; line-height: 1; }
.lang-caret { opacity: 0.7; transition: transform 0.2s; }
.lang-switch.open .lang-caret { transform: rotate(180deg); }
.lang-menu {
  position: absolute; top: calc(100% + 8px); right: 0;
  background: #fff; border: 1px solid var(--line); border-radius: 14px;
  box-shadow: var(--shadow-pop);
  list-style: none; padding: 6px; min-width: 180px;
  opacity: 0; transform: translateY(-6px) scale(0.98); pointer-events: none;
  transition: opacity 0.15s ease, transform 0.15s ease;
}
.lang-switch.open .lang-menu { opacity: 1; transform: none; pointer-events: auto; }
.lang-menu li {
  display: flex; align-items: center; gap: 10px;
  padding: 9px 12px; border-radius: 9px;
  font-size: 14px; font-weight: 500; color: var(--ink); cursor: pointer;
}
.lang-menu li:hover { background: var(--bg-soft); }
.lang-menu li.active { background: #eef0ff; color: var(--accent); }

.nav.scrolled { background: rgba(10, 13, 20, 0.92); box-shadow: 0 4px 24px rgba(0, 0, 0, 0.3); }

/* Burger (mobile) */
.nav-burger { display: none; background: none; border: none; cursor: pointer; padding: 8px; }
.nav-burger span { display: block; width: 20px; height: 2px; background: #fff; margin: 4px 0; border-radius: 2px; }

/* ---------- Hero ---------- */
.hero {
  position: relative; overflow: hidden;
  background: radial-gradient(1200px 600px at 80% -10%, #1a1f35 0%, var(--dark) 55%);
  padding: 150px 0 110px;
}
.hero-glow { position: absolute; border-radius: 50%; filter: blur(90px); opacity: 0.35; pointer-events: none; }
.hero-glow-1 { width: 520px; height: 520px; background: #6366f1; top: -160px; right: -80px; }
.hero-glow-2 { width: 380px; height: 380px; background: #d946ef; bottom: -180px; left: -120px; opacity: 0.18; }
.hero-glow-3 { width: 480px; height: 480px; background: #8b5cf6; top: -180px; left: 30%; opacity: 0.22; }

.hero-inner { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 56px; align-items: center; position: relative; }

.badge {
  display: inline-flex; align-items: center; gap: 8px;
  background: rgba(255, 255, 255, 0.07);
  border: 1px solid var(--dark-line);
  color: #c7cbf5; font-size: 13px; font-weight: 600;
  padding: 7px 14px; border-radius: 999px; margin-bottom: 24px;
}
.badge-dot { width: 7px; height: 7px; border-radius: 50%; background: #34d399; box-shadow: 0 0 8px #34d399; }

.hero-title {
  color: #fff; font-size: clamp(36px, 5vw, 56px);
  font-weight: 800; letter-spacing: -0.03em; line-height: 1.12;
  margin-bottom: 22px;
}
.grad-text { background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero-sub { color: var(--dark-ink-2); font-size: 17px; max-width: 520px; margin-bottom: 34px; }
.hero-cta { display: flex; flex-direction: column; align-items: flex-start; gap: 14px; }
.hero-cta-btns { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; }
.hero-dl-note { color: var(--dark-ink-2); font-size: 13px; }

/* CSS phone mockup */
.hero-phone { display: flex; justify-content: center; position: relative; }
.phone {
  width: 300px; background: #161a26;
  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 40px; padding: 14px;
  box-shadow: var(--shadow-pop);
  animation: float 6s ease-in-out infinite;
  position: relative; z-index: 2;
}
.phone-notch {
  width: 96px; height: 22px; background: #0a0d14;
  border-radius: 999px; margin: 0 auto 10px;
}
.phone-screen {
  background: linear-gradient(180deg, #10131c, #171b28);
  border-radius: 26px; padding: 18px 16px; min-height: 420px;
  display: flex; flex-direction: column; gap: 14px;
  border: 1px solid rgba(255, 255, 255, 0.05);
}
.ps-head { display: flex; align-items: center; gap: 10px; }
.ps-rec {
  display: inline-flex; align-items: center; gap: 6px;
  color: #f87171; font-size: 11px; font-weight: 700; letter-spacing: 0.06em;
  background: rgba(248, 113, 113, 0.12);
  padding: 4px 9px; border-radius: 999px;
}
.ps-rec-dot { width: 6px; height: 6px; border-radius: 50%; background: #f87171; animation: pulse 1.4s ease-in-out infinite; }
.ps-title { color: var(--dark-ink-2); font-size: 12px; font-weight: 500; }

.ps-wave { display: flex; align-items: center; gap: 3px; height: 44px; }
.ps-wave span {
  flex: 1; background: linear-gradient(180deg, #818cf8, #6366f1);
  border-radius: 3px; min-width: 2px;
  animation: wave 1.1s ease-in-out infinite;
}
.ps-wave span:nth-child(3n)   { animation-delay: 0.15s; height: 30%; }
.ps-wave span:nth-child(3n+1) { animation-delay: 0.35s; height: 70%; }
.ps-wave span:nth-child(4n)   { animation-delay: 0.5s; height: 45%; }
.ps-wave span:nth-child(5n)   { animation-delay: 0.75s; height: 90%; }

.ps-lines { display: flex; flex-direction: column; gap: 10px; flex: 1; }
.ps-line {
  display: flex; gap: 10px; align-items: flex-start;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: 12px; padding: 10px 12px;
  animation: fadeUp 0.6s ease both;
}
.ps-line:nth-child(2) { animation-delay: 0.3s; }
.ps-line:nth-child(3) { animation-delay: 0.6s; }
.ps-spk {
  flex-shrink: 0; width: 24px; height: 24px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 700; color: #fff;
}
.spk-a { background: linear-gradient(135deg, #6366f1, #8b5cf6); }
.spk-b { background: linear-gradient(135deg, #0ea5e9, #06b6d4); }
.ps-text { color: #d5dae6; font-size: 12.5px; line-height: 1.5; }

.ps-kw {
  display: flex; align-items: center; gap: 8px; flex-wrap: wrap;
  border-top: 1px solid rgba(255, 255, 255, 0.06); padding-top: 14px;
}
.ps-kw-label { color: var(--dark-ink-2); font-size: 11px; font-weight: 600; letter-spacing: 0.05em; text-transform: uppercase; }
.ps-chip {
  background: rgba(99, 102, 241, 0.16); color: #a5b4fc;
  font-size: 11.5px; font-weight: 600;
  padding: 4px 10px; border-radius: 999px;
}
.phone-shadow {
  position: absolute; bottom: -30px; left: 50%; transform: translateX(-50%);
  width: 260px; height: 40px; background: rgba(99, 102, 241, 0.35);
  filter: blur(48px); border-radius: 50%;
}

@keyframes float { 0%, 100% { transform: translateY(0); } 50% { transform: translateY(-12px); } }
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.3; } }
@keyframes wave { 0%, 100% { transform: scaleY(0.4); } 50% { transform: scaleY(1); } }
@keyframes fadeUp { from { opacity: 0; transform: translateY(10px); } to { opacity: 1; transform: none; } }

/* ---------- Sections ---------- */
.section { padding: 104px 0; }
.section-alt { background: var(--bg-soft); }
.sec-head { text-align: center; max-width: 720px; margin: 0 auto 64px; }
.sec-title { font-size: clamp(28px, 3.6vw, 40px); font-weight: 800; letter-spacing: -0.025em; line-height: 1.2; }
.sec-title.light { color: #fff; }
.sec-sub { color: var(--ink-3); font-size: 17px; margin-top: 16px; }
.section-dark .sec-sub { color: var(--dark-ink-2); }

/* Features */
.feat-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.feat-card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px 26px; box-shadow: var(--shadow-card);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.feat-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-pop); }
.feat-card h3 { font-size: 17px; font-weight: 700; margin: 16px 0 8px; letter-spacing: -0.01em; }
.feat-card p { color: var(--ink-3); font-size: 14.5px; }
.feat-ic {
  width: 44px; height: 44px; border-radius: 12px;
  display: flex; align-items: center; justify-content: center; color: #fff;
}
.fi-violet { background: linear-gradient(135deg, #8b5cf6, #6366f1); }
.fi-blue   { background: linear-gradient(135deg, #0ea5e9, #3b82f6); }
.fi-teal   { background: linear-gradient(135deg, #14b8a6, #0d9488); }
.fi-amber  { background: linear-gradient(135deg, #f59e0b, #f97316); }
.fi-rose   { background: linear-gradient(135deg, #f43f5e, #ec4899); }
.fi-green  { background: linear-gradient(135deg, #22c55e, #16a34a); }

/* How it works */
.how-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.how-step {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 28px 24px; position: relative; box-shadow: var(--shadow-card);
}
.how-num {
  font-size: 13px; font-weight: 800; letter-spacing: 0.08em;
  background: var(--grad); -webkit-background-clip: text; background-clip: text; color: transparent;
}
.how-step h3 { font-size: 17px; font-weight: 700; margin: 10px 0 6px; }
.how-step p { color: var(--ink-3); font-size: 14.5px; }

/* Use cases */
.uc-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.uc-card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px 24px; box-shadow: var(--shadow-card);
  display: flex; flex-direction: column;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.uc-card:hover { transform: translateY(-4px); box-shadow: var(--shadow-pop); }
.uc-head { display: flex; align-items: center; gap: 12px; margin-bottom: 14px; }
.uc-avatar {
  flex-shrink: 0; width: 46px; height: 46px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 21px; color: #fff;
}
.av-1 { background: linear-gradient(135deg, #6366f1, #8b5cf6); }
.av-2 { background: linear-gradient(135deg, #0ea5e9, #3b82f6); }
.av-3 { background: linear-gradient(135deg, #14b8a6, #0d9488); }
.av-4 { background: linear-gradient(135deg, #f59e0b, #f97316); }
.av-5 { background: linear-gradient(135deg, #f43f5e, #ec4899); }
.av-6 { background: linear-gradient(135deg, #22c55e, #16a34a); }
.uc-name { display: block; font-weight: 700; font-size: 15px; }
.uc-role { display: block; color: var(--ink-3); font-size: 12.5px; }
.uc-quote { color: var(--ink-2); font-size: 14.5px; line-height: 1.7; }

/* Privacy (dark) */
.section-dark {
  position: relative; overflow: hidden;
  background: radial-gradient(900px 500px at 50% -10%, #181d30 0%, var(--dark) 60%);
}
.priv-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.priv-card {
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--dark-line);
  border-radius: var(--radius); padding: 30px 26px;
}
.priv-card h3 { color: #fff; font-size: 17px; font-weight: 700; margin: 16px 0 8px; }
.priv-card p { color: var(--dark-ink-2); font-size: 14.5px; }

/* Download */
.dl-card {
  text-align: center; max-width: 640px; margin: 0 auto;
  background: #fff; border: 1px solid var(--line);
  border-radius: 24px; padding: 56px 40px;
  box-shadow: var(--shadow-pop);
}
.dl-logo { width: 72px; height: 72px; border-radius: 18px; margin-bottom: 20px; }
.dl-card h2 { font-size: clamp(26px, 3vw, 34px); font-weight: 800; letter-spacing: -0.02em; margin-bottom: 8px; }
.dl-btn { margin: 28px 0 26px; min-width: 240px; }
.dl-reqs { list-style: none; display: flex; flex-direction: column; gap: 8px; }
.dl-reqs li { color: var(--ink-3); font-size: 14px; }
.dl-reqs li::before { content: "✓"; color: #22c55e; font-weight: 700; margin-right: 8px; }
.dl-ios { display: inline-block; margin-top: 22px; color: var(--ink-3); font-size: 13px; font-style: italic; }

/* Model table */
.model-tbl {
  max-width: 880px; margin: 48px auto 0;
  background: #fff; border: 1px solid var(--line);
  border-radius: var(--radius); padding: 28px;
  box-shadow: var(--shadow-card);
}
.mt-title { font-size: 18px; font-weight: 700; letter-spacing: -0.01em; margin-bottom: 18px; text-align: center; }
.mt-scroll { overflow-x: auto; }
.model-tbl table { width: 100%; border-collapse: collapse; font-size: 14px; min-width: 560px; }
.model-tbl th {
  text-align: left; font-weight: 600; color: var(--ink-3);
  font-size: 12.5px; text-transform: uppercase; letter-spacing: 0.05em;
  padding: 10px 12px; border-bottom: 2px solid var(--line);
}
.model-tbl td { padding: 12px; border-bottom: 1px solid var(--line); color: var(--ink-2); }
.model-tbl tr:last-child td { border-bottom: none; }
.model-tbl td:first-child { font-weight: 600; color: var(--ink); white-space: nowrap; }
.mt-ver { margin-top: 16px; text-align: center; color: var(--ink-3); font-size: 13px; }
.tag {
  display: inline-block; padding: 3px 10px; border-radius: 999px;
  font-size: 12px; font-weight: 600; white-space: nowrap;
}
.tag-core { background: #eef0ff; color: #4f46e5; }
.tag-opt { background: #f0fdf4; color: #16a34a; }

/* FAQ */
.faq-list { max-width: 760px; margin: 0 auto; display: flex; flex-direction: column; gap: 14px; }
.faq-item {
  background: #fff; border: 1px solid var(--line); border-radius: 14px;
  padding: 0 22px; box-shadow: var(--shadow-card);
  transition: border-color 0.15s;
}
.faq-item:hover { border-color: #c9cdf5; }
.faq-item summary {
  cursor: pointer; list-style: none; padding: 20px 0;
  font-weight: 600; font-size: 16px; position: relative; padding-right: 36px;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; position: absolute; right: 4px; top: 50%;
  transform: translateY(-50%); font-size: 20px; font-weight: 400; color: var(--ink-3);
  transition: transform 0.2s;
}
.faq-item[open] summary::after { content: "−"; }
.faq-item p { color: var(--ink-3); font-size: 14.5px; padding-bottom: 20px; }

/* Footer */
.footer { background: var(--dark-2); border-top: 1px solid var(--dark-line); padding: 48px 0 40px; }
.footer-inner { display: flex; flex-wrap: wrap; align-items: center; gap: 28px; justify-content: space-between; }
.footer-brand { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }
.footer-tagline { color: var(--dark-ink-2); font-size: 13px; width: 100%; margin-top: 4px; }
.footer-links { display: flex; gap: 24px; flex-wrap: wrap; }
.footer-links a { color: var(--dark-ink-2); text-decoration: none; font-size: 13.5px; transition: color 0.15s; }
.footer-links a:hover { color: #fff; }
.footer-meta { display: flex; flex-direction: column; gap: 4px; }
.footer-meta p { color: var(--dark-ink-2); font-size: 12.5px; }
.footer-rights { color: #565f70; font-size: 12.5px; width: 100%; margin-top: 8px; }

/* ---------- Doc pages (privacy / sdk-list) ---------- */
.doc-page { background: #fff; }
.doc-hero {
  background: radial-gradient(1000px 500px at 50% -10%, #1a1f35 0%, var(--dark) 60%);
  padding: 140px 0 64px; text-align: center;
}
.doc-hero h1 { color: #fff; font-size: clamp(28px, 4vw, 42px); font-weight: 800; letter-spacing: -0.02em; }
.doc-hero p { color: var(--dark-ink-2); margin-top: 12px; font-size: 14px; }
.doc-body { max-width: 760px; margin: 0 auto; padding: 56px 24px 96px; }
.doc-sec { margin-bottom: 40px; }
.doc-sec h2 {
  font-size: 19px; font-weight: 700; letter-spacing: -0.01em; margin-bottom: 10px;
  padding-left: 14px; border-left: 3px solid var(--accent);
}
.doc-sec p { color: var(--ink-2); font-size: 15px; line-height: 1.75; }
.doc-tbl { width: 100%; border-collapse: collapse; font-size: 14px; margin-top: 8px; }
.doc-tbl th {
  text-align: left; font-weight: 600; color: var(--ink-3); font-size: 12.5px;
  text-transform: uppercase; letter-spacing: 0.05em;
  padding: 10px 12px; border-bottom: 2px solid var(--line);
}
.doc-tbl td { padding: 12px; border-bottom: 1px solid var(--line); color: var(--ink-2); }
.doc-tbl td:first-child { font-weight: 600; color: var(--ink); }
.doc-intro { color: var(--ink-2); font-size: 15px; line-height: 1.75; margin-bottom: 36px; }

/* Reveal on scroll */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.visible { opacity: 1; transform: none; }

/* ---------- Responsive ---------- */
@media (max-width: 960px) {
  .hero-inner { grid-template-columns: 1fr; gap: 64px; }
  .hero-copy { text-align: center; }
  .hero-sub { margin-left: auto; margin-right: auto; }
  .hero-cta { align-items: center; }
  .hero-cta-btns { justify-content: center; }
  .feat-grid { grid-template-columns: repeat(2, 1fr); }
  .uc-grid { grid-template-columns: repeat(2, 1fr); }
  .how-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .nav-links, .nav-cta { display: none; }
  .nav-burger { display: block; margin-left: auto; }
  .nav-actions { margin-left: auto; }
  .nav-burger { margin-left: 0; }
  .hero { padding: 120px 0 80px; }
  .section { padding: 72px 0; }
  .feat-grid, .uc-grid, .priv-grid, .how-grid { grid-template-columns: 1fr; }
  .phone { width: 270px; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
}