/* ===========================================================
   Signal 中文官网 · dl-signal.cn
   Signal-inspired design system
   =========================================================== */

:root {
  --blue: #3a76f0;
  --blue-dark: #2c5fd0;
  --blue-deep: #1b3a8c;
  --ink: #1b1b21;
  --ink-soft: #44464f;
  --muted: #6b6e7b;
  --line: #e7e8ee;
  --bg: #ffffff;
  --bg-soft: #f6f7fb;
  --bg-tint: #eef3fe;
  --radius: 16px;
  --radius-lg: 24px;
  --shadow: 0 10px 40px rgba(27, 27, 33, 0.08);
  --shadow-soft: 0 4px 18px rgba(27, 27, 33, 0.06);
  --max: 1160px;
  --font: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI",
    "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue",
    Arial, sans-serif;
}

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

html { scroll-behavior: smooth; }

/* ===== Skip link (accessibility / SEO) ===== */
.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 9999;
  background: var(--blue);
  color: #fff;
  padding: 10px 18px;
  border-radius: 0 0 10px 0;
  font-size: 14px;
  font-weight: 600;
}
.skip-link:focus { left: 0; }

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

.container {
  width: 100%;
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 24px;
}

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

h1, h2, h3, h4 { line-height: 1.18; letter-spacing: -0.01em; color: var(--ink); }

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: 16px;
  padding: 12px 26px;
  border-radius: 999px;
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform 0.15s ease, background 0.2s ease, color 0.2s ease,
    border-color 0.2s ease, box-shadow 0.2s ease;
  white-space: nowrap;
}
.btn:active { transform: translateY(1px); }
.btn-sm { padding: 9px 20px; font-size: 15px; }
.btn-lg { padding: 15px 34px; font-size: 17px; }

.btn-primary { background: var(--blue); color: #fff; }
.btn-primary:hover { background: var(--blue-dark); box-shadow: 0 8px 22px rgba(58, 118, 240, 0.35); }

.btn-ghost { background: transparent; color: var(--blue); border-color: var(--blue); }
.btn-ghost:hover { background: var(--bg-tint); }

.btn-white { background: #fff; color: var(--blue); }
.btn-white:hover { background: #eef3fe; }

.btn-ghost-light { background: transparent; color: #fff; border-color: rgba(255,255,255,0.6); }
.btn-ghost-light:hover { background: rgba(255,255,255,0.12); border-color: #fff; }

/* ===== Header ===== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 70px;
  gap: 24px;
}
.brand { display: inline-flex; align-items: center; gap: 10px; }
.brand-img { height: 30px; width: auto; display: block; }
.brand-badge {
  font-size: 12px; font-weight: 700; letter-spacing: 0.04em;
  color: var(--blue); background: var(--bg-tint);
  border: 1px solid #d6e2fd; border-radius: 999px;
  padding: 2px 9px; line-height: 1.4; white-space: nowrap;
}
.footer-brand-link .brand-img { height: 30px; }

/* ===== Breadcrumb ===== */
.breadcrumb { border-bottom: 1px solid var(--line); background: #fff; font-size: 13.5px; }
.breadcrumb .container { padding-top: 12px; padding-bottom: 12px; }
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--blue); }
.breadcrumb > .container > span { color: var(--muted); margin: 0 7px; }
.breadcrumb [aria-current="page"] { color: var(--ink); font-weight: 600; margin-left: 0; }
.brand-logo { width: 32px; height: 32px; }
.brand-name { font-weight: 700; font-size: 21px; letter-spacing: -0.02em; }

.main-nav { display: flex; gap: 30px; margin-left: auto; }
.main-nav a {
  font-size: 15.5px;
  font-weight: 500;
  color: var(--ink-soft);
  transition: color 0.2s ease;
  position: relative;
}
.main-nav a:hover { color: var(--blue); }

.nav-actions { display: flex; align-items: center; gap: 14px; }

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 6px;
}
.nav-toggle span {
  width: 24px; height: 2px; background: var(--ink); border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease;
}
.nav-toggle.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav-toggle.open span:nth-child(2) { opacity: 0; }
.nav-toggle.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* ===== Hero ===== */
.hero {
  background: linear-gradient(180deg, #eef3fe 0%, #f8faff 60%, #ffffff 100%);
  padding: 72px 0 80px;
  overflow: hidden;
}
.hero-inner {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  align-items: center;
  gap: 48px;
}
.hero-copy h1 {
  font-size: clamp(44px, 6vw, 72px);
  font-weight: 800;
  letter-spacing: -0.03em;
}
.hero-sub {
  margin-top: 22px;
  font-size: 19px;
  color: var(--ink-soft);
  max-width: 30em;
}
.hero-cta { margin-top: 32px; display: flex; gap: 14px; flex-wrap: wrap; }
.hero-note { margin-top: 18px; font-size: 14px; color: var(--muted); letter-spacing: 0.02em; }

/* Hero phones — two real device screenshots, tilted & overlapping */
.hero-art {
  position: relative;
  height: 560px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.phone-img {
  position: absolute;
  width: auto;
  filter: drop-shadow(0 30px 55px rgba(27, 27, 33, 0.28));
}
.phone-front {
  height: 540px;
  transform: rotate(-9deg) translateX(-46px);
  z-index: 2;
  animation: floatA 7s ease-in-out infinite;
}
.phone-back {
  height: 500px;
  transform: rotate(7deg) translateX(70px);
  z-index: 1;
  animation: floatB 7s ease-in-out infinite;
}
@keyframes floatA {
  0%, 100% { transform: rotate(-9deg) translate(-46px, 0); }
  50%      { transform: rotate(-9deg) translate(-46px, -14px); }
}
@keyframes floatB {
  0%, 100% { transform: rotate(7deg) translate(70px, 0); }
  50%      { transform: rotate(7deg) translate(70px, 12px); }
}

/* ===== Trust bar ===== */
.trustbar { border-bottom: 1px solid var(--line); background: #fff; }
.trust-inner {
  display: grid; grid-template-columns: repeat(4, 1fr);
  text-align: center; padding: 30px 24px;
}
.trust-item strong { display: block; font-size: 30px; font-weight: 800; color: var(--blue); letter-spacing: -0.02em; }
.trust-item span { font-size: 14px; color: var(--muted); }

/* ===== Sections ===== */
.section { padding: 88px 0; }
.section-alt { background: var(--bg-soft); }
.section-head { text-align: center; max-width: 720px; margin: 0 auto 54px; }
.eyebrow {
  display: inline-block; font-size: 14px; font-weight: 700; letter-spacing: 0.08em;
  text-transform: uppercase; color: var(--blue); margin-bottom: 14px;
}
.eyebrow.light { color: rgba(255,255,255,0.85); }
.section-head h2 { font-size: clamp(30px, 4vw, 44px); font-weight: 800; }
.section-lead { margin-top: 18px; font-size: 18px; color: var(--ink-soft); }

/* ===== Feature rows (alternating image + text) ===== */
.feature-rows { display: flex; flex-direction: column; gap: 72px; }
.feature-row {
  display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 60px;
}
.feature-row:nth-of-type(even) .fr-media { order: 2; }

.fr-frame {
  border-radius: 28px; overflow: hidden;
  display: flex; align-items: center; justify-content: center;
}
.fr-frame img { display: block; }
.fr-frame.pad { padding: 40px; }
.fr-frame.pad img { width: 100%; max-width: 400px; height: auto; }
.fr-frame.cover img { width: 100%; height: auto; }

.tint-a { background: #eaf1fe; }
.tint-b { background: #f1ecfd; }
.tint-c { background: #e7f6ee; }
.tint-d { background: #fdf0e8; }

.fr-copy .eyebrow { margin-bottom: 10px; }
.fr-copy h3 { font-size: clamp(26px, 3vw, 36px); font-weight: 800; margin-bottom: 16px; }
.fr-copy p { font-size: 17px; color: var(--ink-soft); }
.fr-cta { margin-top: 26px; display: flex; gap: 14px; flex-wrap: wrap; }

/* ===== Privacy ===== */
.privacy-inner {
  display: grid; grid-template-columns: 1fr 1fr; gap: 56px; align-items: center;
}
.privacy-copy h2 { font-size: clamp(28px, 3.6vw, 40px); font-weight: 800; margin-bottom: 20px; }
.privacy-copy > p { font-size: 17px; color: var(--ink-soft); margin-bottom: 24px; }
.check-list { list-style: none; margin-bottom: 30px; }
.check-list li {
  position: relative; padding-left: 34px; margin-bottom: 14px; font-size: 16px; color: var(--ink-soft);
}
.check-list li::before {
  content: "✓"; position: absolute; left: 0; top: 0;
  width: 24px; height: 24px; background: var(--blue); color: #fff;
  border-radius: 50%; display: flex; align-items: center; justify-content: center;
  font-size: 13px; font-weight: 700;
}

.privacy-art { display: flex; justify-content: center; }
.lock-card {
  width: 100%; max-width: 380px; aspect-ratio: 1 / 0.92;
  background: linear-gradient(150deg, var(--blue) 0%, var(--blue-deep) 100%);
  border-radius: var(--radius-lg); color: #fff;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  gap: 8px; box-shadow: 0 24px 60px rgba(58,118,240,0.35); padding: 40px;
}
.lock-icon { font-size: 64px; }
.lock-text { font-size: 24px; font-weight: 700; }
.lock-sub { font-size: 14px; opacity: 0.8; letter-spacing: 0.05em; }
.lock-flow {
  margin-top: 22px; display: flex; align-items: center; gap: 8px;
  font-size: 14px; font-weight: 600;
}
.lock-flow .dash { width: 26px; height: 2px; background: rgba(255,255,255,0.5); }
.lock-flow .cipher {
  background: rgba(255,255,255,0.18); padding: 4px 10px; border-radius: 8px; letter-spacing: 2px;
}

/* ===== Download ===== */
.dl-title { font-size: clamp(24px, 2.6vw, 30px); font-weight: 800; margin-bottom: 14px; }

/* 手机版 block */
.dl-block {
  display: grid; grid-template-columns: 1fr 1fr; align-items: center; gap: 56px;
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius-lg);
  padding: 40px; margin-bottom: 28px;
}
.dl-block-media { display: flex; justify-content: center; }
.dl-block-media img { width: 100%; max-width: 420px; height: auto; display: block; }
.dl-block-copy > p { font-size: 16.5px; color: var(--ink-soft); margin-bottom: 22px; }

.dl-store-buttons { display: flex; flex-direction: column; gap: 12px; max-width: 360px; }
.store-btn {
  display: flex; align-items: center; gap: 14px;
  background: #0e1116; color: #fff; border-radius: 14px; padding: 12px 20px;
  transition: transform 0.15s ease, background 0.2s ease;
}
.store-btn:hover { background: #20242c; transform: translateY(-2px); }
.store-icon {
  width: 26px; height: 26px; min-width: 26px; color: #fff;
  display: inline-flex; align-items: center; justify-content: center;
}
.ico { width: 100%; height: 100%; display: block; fill: currentColor; }
.store-icon .ico { width: 24px; height: 24px; }
.store-text { display: flex; flex-direction: column; font-weight: 600; font-size: 16px; }
.store-text small { font-weight: 400; font-size: 11px; opacity: 0.75; }
.dl-tip { margin-top: 18px; font-size: 14px; color: var(--muted); }

/* 电脑版 */
.dl-desktop {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius-lg); padding: 40px;
}
.dl-desktop-head { text-align: center; max-width: 680px; margin: 0 auto 32px; }
.dl-prereq {
  font-size: 14.5px; color: #8a5a00; background: #fff6e5;
  border: 1px solid #ffe2a8; border-radius: 12px; padding: 12px 18px; display: inline-block;
}
.dl-desktop-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-bottom: 24px; }
.dl-desktop-card {
  border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden;
  display: flex; flex-direction: column; transition: box-shadow 0.2s ease, transform 0.2s ease;
}
.dl-desktop-card:hover { box-shadow: var(--shadow); transform: translateY(-3px); }
.dl-desktop-shot { background: var(--bg-soft); padding: 22px 22px 0; }
.dl-desktop-shot img { width: 100%; height: auto; display: block; border-radius: 10px 10px 0 0; box-shadow: 0 -2px 14px rgba(27,27,33,0.06); }
.dl-desktop-info { padding: 22px 24px 26px; }
.dl-desktop-info h4 { font-size: 20px; display: flex; align-items: center; gap: 10px; }
.os-mark { width: 22px; height: 22px; display: inline-flex; align-items: center; justify-content: center; }
.os-mark .ico { width: 22px; height: 22px; }
.os-apple   { color: #1b1b21; }
.os-windows { color: #00a4ef; }
.os-linux   { color: #1b1b21; }
.dl-desktop-info p { font-size: 14px; color: var(--muted); margin: 4px 0 16px; }
.dl-win-buttons { display: flex; flex-wrap: wrap; gap: 10px; }

/* Linux */
.dl-linux { border: 1px solid var(--line); border-radius: var(--radius); padding: 26px 28px; }
.dl-linux-head h4 { font-size: 20px; display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
.dl-linux-head p { font-size: 14.5px; color: var(--ink-soft); margin-bottom: 18px; }
.dl-code {
  background: #0e1116; color: #e6e8ee; border-radius: 12px; padding: 20px 22px;
  overflow-x: auto; font-size: 13px; line-height: 1.7;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}
.dl-code code { white-space: pre; }
.dl-copy-btn {
  margin-top: 14px; font-size: 14px; font-weight: 600; color: var(--blue);
  background: var(--bg-tint); border: none; border-radius: 999px; padding: 9px 18px; cursor: pointer;
  transition: background 0.2s ease;
}
.dl-copy-btn:hover { background: #dfe9fe; }
.dl-copy-btn.copied { background: #e7f6ee; color: #1a8c4a; }

/* ===== Nonprofit ===== */
.section-blue {
  background: linear-gradient(150deg, var(--blue) 0%, var(--blue-deep) 100%);
  color: #fff; text-align: center;
}
.nonprofit-inner { max-width: 760px; margin: 0 auto; }
.section-blue h2 { color: #fff; font-size: clamp(28px, 3.6vw, 42px); font-weight: 800; margin-bottom: 20px; }
.section-blue p { font-size: 18px; color: rgba(255,255,255,0.9); margin-bottom: 32px; }
.nonprofit-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

/* ===== FAQ ===== */
.faq-list { max-width: 760px; margin: 0 auto; }
.faq-item {
  border: 1px solid var(--line); border-radius: var(--radius);
  margin-bottom: 14px; background: #fff; overflow: hidden;
}
.faq-item summary {
  cursor: pointer; list-style: none; padding: 20px 24px;
  font-size: 17px; font-weight: 600; display: flex; justify-content: space-between; align-items: center;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: "+"; font-size: 24px; font-weight: 400; color: var(--blue); transition: transform 0.2s ease;
}
.faq-item[open] summary::after { transform: rotate(45deg); }
.faq-item p { padding: 0 24px 22px; color: var(--ink-soft); font-size: 15.5px; }

/* ===== CTA banner ===== */
.cta-banner { padding: 80px 0; text-align: center; background: var(--bg-tint); }
.cta-banner h2 { font-size: clamp(26px, 3.4vw, 38px); font-weight: 800; margin-bottom: 28px; }

/* ===== Footer ===== */
.site-footer { background: #0e1116; color: #c8cad2; padding: 64px 0 32px; }
.footer-inner {
  display: grid; grid-template-columns: 1.2fr 3fr; gap: 48px; padding-bottom: 44px;
  border-bottom: 1px solid rgba(255,255,255,0.1);
}
.footer-brand .brand-name { color: #fff; }
.footer-tag { margin-top: 14px; font-size: 14px; color: #8a8d99; max-width: 22em; }
.footer-cols { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.footer-col h4 { color: #fff; font-size: 14px; margin-bottom: 16px; letter-spacing: 0.04em; }
.footer-col a { display: block; font-size: 14px; color: #a7aab5; margin-bottom: 10px; transition: color 0.2s ease; }
.footer-col a:hover { color: var(--blue); }
.footer-bottom { padding-top: 26px; font-size: 13px; color: #7d8090; }
.footer-bottom p { margin-bottom: 6px; }
.footer-disclaimer { color: #5f626e; }

/* ===== Reveal-on-scroll ===== */
.reveal { opacity: 0; transform: translateY(22px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.revealed { opacity: 1; transform: translateY(0); }

/* ===== Toast ===== */
.toast {
  position: fixed;
  left: 50%;
  bottom: 28px;
  transform: translateX(-50%) translateY(140%);
  max-width: 90%;
  width: 460px;
  background: #0e1116;
  color: #fff;
  padding: 16px 22px;
  border-radius: 14px;
  font-size: 14.5px;
  line-height: 1.5;
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.3);
  z-index: 999;
  opacity: 0;
  transition: transform 0.35s cubic-bezier(0.2, 0.8, 0.2, 1), opacity 0.35s ease;
}
.toast.show { transform: translateX(-50%) translateY(0); opacity: 1; }

@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; transition: none; }
  .phone-front, .phone-back { animation: none; }
  html { scroll-behavior: auto; }
}

/* ===== Responsive ===== */
@media (max-width: 980px) {
  .hero-inner { grid-template-columns: 1fr; text-align: center; gap: 40px; }
  .hero-sub { margin-left: auto; margin-right: auto; }
  .hero-cta { justify-content: center; }
  .hero-art { height: 480px; }
  .phone-front { height: 460px; }
  .phone-back { height: 426px; }
  @keyframes floatA { 0%,100% { transform: rotate(-9deg) translate(-40px,0); } 50% { transform: rotate(-9deg) translate(-40px,-12px); } }
  @keyframes floatB { 0%,100% { transform: rotate(7deg) translate(58px,0); } 50% { transform: rotate(7deg) translate(58px,10px); } }
  .feature-rows { gap: 48px; }
  .feature-row { grid-template-columns: 1fr; gap: 28px; text-align: center; }
  .feature-row:nth-of-type(even) .fr-media { order: 0; }
  .fr-copy .eyebrow { margin-top: 4px; }
  .fr-cta { justify-content: center; }
  .fr-frame.pad img { max-width: 320px; }
  .privacy-inner { grid-template-columns: 1fr; gap: 40px; }
  .privacy-copy { text-align: center; }
  .check-list { display: inline-block; text-align: left; }
  .dl-block { grid-template-columns: 1fr; gap: 28px; text-align: center; padding: 32px 24px; }
  .dl-block-media { order: -1; }
  .dl-store-buttons { margin-left: auto; margin-right: auto; }
  .dl-desktop { padding: 32px 24px; }
  .dl-desktop-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr; gap: 32px; }
}

@media (max-width: 720px) {
  .main-nav {
    position: fixed; top: 70px; left: 0; right: 0;
    flex-direction: column; gap: 0; background: #fff;
    border-bottom: 1px solid var(--line); padding: 8px 0;
    transform: translateY(-130%); transition: transform 0.3s ease; box-shadow: var(--shadow);
  }
  .main-nav.open { transform: translateY(0); }
  .main-nav a { padding: 14px 24px; border-bottom: 1px solid var(--line); }
  .nav-toggle { display: flex; }
  .nav-actions .btn-sm { display: none; }
  .trust-inner { grid-template-columns: repeat(2, 1fr); gap: 24px; }
  .section { padding: 64px 0; }
}

@media (max-width: 520px) {
  .fr-frame.pad { padding: 28px; }
  .download-grid { grid-template-columns: repeat(2, 1fr); }
  .hero-copy h1 { font-size: 42px; }
  .hero-art { height: 380px; }
  .phone-front { height: 350px; transform: rotate(-9deg) translateX(-30px); }
  .phone-back { height: 322px; transform: rotate(7deg) translateX(42px); }
}

/* ===========================================================
   v2 — Homepage redesign + dedicated Download page
   （沿用官网主题色 #3a76f0，整体版式与初版区分）
   =========================================================== */

/* ----- Centered hero (homepage v2) ----- */
.hero-v2 {
  background: radial-gradient(1100px 560px at 50% -140px, #e6eefe 0%, #f3f7ff 46%, #ffffff 100%);
  padding: 80px 0 0;
  text-align: center;
  overflow: hidden;
}
.hero-badges { display: flex; flex-wrap: wrap; gap: 10px; justify-content: center; margin-bottom: 24px; }
.pill {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 13px; font-weight: 600; color: var(--blue);
  background: #fff; border: 1px solid #d6e2fd; border-radius: 999px;
  padding: 6px 14px; box-shadow: var(--shadow-soft);
}
.hero-v2 h1 { font-size: clamp(40px, 6vw, 68px); font-weight: 800; letter-spacing: -0.03em; max-width: 15em; margin: 0 auto; }
.hero-v2 .hero-sub { margin: 22px auto 0; font-size: 19px; color: var(--ink-soft); max-width: 33em; }
.hero-v2 .hero-cta { margin-top: 30px; display: flex; gap: 14px; flex-wrap: wrap; justify-content: center; }
.hero-v2 .hero-note { margin-top: 16px; font-size: 14px; color: var(--muted); letter-spacing: 0.02em; }

.hero-showcase { position: relative; margin-top: 52px; height: 470px; display: flex; align-items: flex-end; justify-content: center; }
.hero-showcase img { position: absolute; bottom: 0; width: auto; filter: drop-shadow(0 26px 52px rgba(27, 27, 33, 0.26)); }
.hero-showcase .sc-front { height: 450px; z-index: 2; transform: translateX(56px); animation: floatA 7s ease-in-out infinite; }
.hero-showcase .sc-back  { height: 384px; z-index: 1; transform: translateX(-168px) rotate(-7deg); animation: floatB 7s ease-in-out infinite; }
@keyframes scFront { 0%,100%{ transform: translateX(56px) translateY(0);} 50%{ transform: translateX(56px) translateY(-12px);} }

/* ----- Pill stat strip ----- */
.stat-strip { display: flex; flex-wrap: wrap; gap: 14px; justify-content: center; }
.stat-chip {
  background: #fff; border: 1px solid var(--line); border-radius: 16px;
  padding: 18px 26px; min-width: 150px; box-shadow: var(--shadow-soft);
}
.stat-chip strong { display: block; font-size: 28px; font-weight: 800; color: var(--blue); letter-spacing: -0.02em; }
.stat-chip span { font-size: 13.5px; color: var(--muted); }

/* ----- Feature card grid ----- */
.feature-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.feature-card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius-lg);
  padding: 30px 28px; transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.feature-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.fc-icon { width: 56px; height: 56px; border-radius: 16px; display: flex; align-items: center; justify-content: center; font-size: 28px; margin-bottom: 18px; }
.fc-a { background: #eaf1fe; } .fc-b { background: #f1ecfd; } .fc-c { background: #e7f6ee; }
.fc-d { background: #fdf0e8; } .fc-e { background: #fde8ef; } .fc-f { background: #e8f7fb; }
.feature-card h3 { font-size: 21px; font-weight: 800; margin-bottom: 10px; }
.feature-card p { font-size: 15.5px; color: var(--ink-soft); }

/* ----- Steps ----- */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 26px; }
.step { background: var(--bg-soft); border-radius: var(--radius-lg); padding: 32px 28px; }
.step-num { width: 42px; height: 42px; border-radius: 50%; background: var(--blue); color: #fff; font-weight: 800; font-size: 18px; display: flex; align-items: center; justify-content: center; margin-bottom: 18px; }
.step h3 { font-size: 19px; font-weight: 800; margin-bottom: 8px; }
.step p { font-size: 15px; color: var(--ink-soft); }

/* ----- Comparison table ----- */
.compare-wrap { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius-lg); }
.compare { width: 100%; border-collapse: collapse; min-width: 640px; background: #fff; }
.compare th, .compare td { padding: 16px 18px; text-align: center; border-bottom: 1px solid var(--line); font-size: 15px; }
.compare thead th { font-size: 16px; font-weight: 800; }
.compare tbody th { text-align: left; font-weight: 600; color: var(--ink-soft); }
.compare .col-signal { background: var(--bg-tint); }
.compare thead .col-signal { color: var(--blue); }
.compare tr:last-child td, .compare tr:last-child th { border-bottom: none; }
.yes { color: #1a8c4a; font-weight: 800; }
.no { color: #c0392b; font-weight: 700; }

/* ----- Quotes ----- */
.quotes { display: grid; grid-template-columns: repeat(3, 1fr); gap: 24px; }
.quote-card { background: #fff; border: 1px solid var(--line); border-radius: var(--radius-lg); padding: 28px; }
.quote-mark { font-size: 46px; line-height: 0.6; color: var(--blue); font-weight: 800; display: block; height: 28px; }
.quote-card p { font-size: 16px; color: var(--ink); line-height: 1.7; }
.quote-by { margin-top: 16px; font-size: 14px; color: var(--muted); font-weight: 600; }

/* ----- Download page ----- */
.dl-hero { background: linear-gradient(180deg, #eef3fe 0%, #ffffff 100%); padding: 66px 0 38px; text-align: center; }
.dl-hero .eyebrow { margin-bottom: 12px; }
.dl-hero h1 { font-size: clamp(34px, 5vw, 52px); font-weight: 800; letter-spacing: -0.02em; }
.dl-hero p { margin: 18px auto 0; font-size: 18px; color: var(--ink-soft); max-width: 40em; }
.dl-hero .hero-badges { margin-top: 26px; margin-bottom: 0; }

.req-table { width: 100%; border-collapse: collapse; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.req-table th, .req-table td { padding: 14px 18px; text-align: left; border-bottom: 1px solid var(--line); font-size: 15px; }
.req-table thead th { background: var(--bg-soft); font-weight: 800; }
.req-table tbody th { font-weight: 700; white-space: nowrap; }
.req-table tr:last-child td, .req-table tr:last-child th { border-bottom: none; }

.note-card { background: #fff6e5; border: 1px solid #ffe2a8; color: #8a5a00; border-radius: var(--radius); padding: 18px 22px; font-size: 15px; line-height: 1.7; }
.safe-card { background: #e7f6ee; border: 1px solid #b7e4c9; color: #1a6b3d; border-radius: var(--radius); padding: 18px 22px; font-size: 15px; line-height: 1.7; }

/* ----- v2 responsive ----- */
@media (max-width: 980px) {
  .feature-grid { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: 1fr; }
  .quotes { grid-template-columns: 1fr; }
  .hero-showcase { height: 380px; }
  .hero-showcase .sc-front { height: 360px; transform: translateX(40px); }
  .hero-showcase .sc-back { height: 300px; transform: translateX(-120px) rotate(-7deg); }
}
@media (max-width: 560px) {
  .feature-grid { grid-template-columns: 1fr; }
  .hero-showcase { height: 320px; }
  .hero-showcase .sc-front { height: 300px; transform: translateX(28px); }
  .hero-showcase .sc-back { height: 240px; transform: translateX(-86px) rotate(-7deg); }
  .stat-chip { min-width: 130px; padding: 14px 18px; }
}

/* ===========================================================
   v3 — 官网插画卡片 + 安全分享聊天动画
   =========================================================== */

/* ----- Illustration feature cards (Media/Calls/Stickers/Groups) ----- */
.illus-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 28px; }
.illus-card {
  background: #fff; border: 1px solid var(--line); border-radius: var(--radius-lg);
  padding: 40px 36px; text-align: center;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}
.illus-card:hover { transform: translateY(-4px); box-shadow: var(--shadow); }
.illus-figure {
  border-radius: 20px; padding: 26px; margin-bottom: 24px;
  display: flex; align-items: center; justify-content: center;
}
.illus-figure img { width: 100%; max-width: 320px; height: auto; display: block; }
.illus-card h3 { font-size: 22px; font-weight: 800; margin-bottom: 12px; }
.illus-card p { font-size: 15.5px; color: var(--ink-soft); }

/* ----- "安全分享" chat animation ----- */
.chat-stage {
  background: #b9d3d0;
  border-radius: var(--radius-lg);
  padding: 30px 26px;
  display: flex; flex-direction: column; gap: 14px;
  min-height: 380px; justify-content: center;
  box-shadow: var(--shadow-soft);
}
.chat-msg {
  max-width: 82%; opacity: 0;
  animation: chatPop 8s ease-in-out infinite;
}
.chat-msg.in { align-self: flex-start; }
.chat-msg.out { align-self: flex-end; }
.chat-msg:nth-child(1) { animation-delay: 0.2s; }
.chat-msg:nth-child(2) { animation-delay: 1.1s; }
.chat-msg:nth-child(3) { animation-delay: 2.3s; }
.bubble { padding: 12px 18px; border-radius: 22px; font-size: 16px; line-height: 1.45; font-weight: 500; }
.chat-msg.in .bubble { background: #2f7d7a; color: #fff; border-bottom-left-radius: 6px; }
.chat-msg.out .bubble { background: #8a9097; color: #fff; border-bottom-right-radius: 6px; }
.chat-img { padding: 0; overflow: hidden; border-radius: 22px; border-bottom-left-radius: 6px; max-width: 80%; line-height: 0; box-shadow: 0 8px 20px rgba(0,0,0,0.12); }
.chat-img svg, .chat-img img { display: block; width: 100%; height: auto; }
.chat-time { display: block; margin-top: 4px; font-size: 11px; color: rgba(27,27,33,0.5); text-align: right; }

@keyframes chatPop {
  0%   { opacity: 0; transform: translateY(16px) scale(0.96); }
  7%   { opacity: 1; transform: translateY(0) scale(1); }
  86%  { opacity: 1; transform: translateY(0) scale(1); }
  100% { opacity: 0; transform: translateY(16px) scale(0.96); }
}

/* ----- Breadcrumb ----- */
.breadcrumb { border-bottom: 1px solid var(--line); background: #fff; font-size: 13.5px; }
.breadcrumb .container { padding-top: 12px; padding-bottom: 12px; }
.breadcrumb a { color: var(--muted); }
.breadcrumb a:hover { color: var(--blue); }
.breadcrumb span { color: var(--muted); margin: 0 6px; }
.breadcrumb [aria-current] { color: var(--ink); font-weight: 600; }

@media (prefers-reduced-motion: reduce) {
  .chat-msg { opacity: 1; animation: none; }
}

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