/* ============ 回响 Echo · 官网样式 ============ */
:root{
  --paper:#FAF7F2;
  --paper-2:#F3EDE3;
  --surface:#FFFFFF;
  --ink:#211F1B;
  --ink-2:#6B645A;
  --ink-3:#9A9286;
  --line:#E7DFD2;
  --bronze:#9A6A2F;
  --bronze-soft:#C9954E;
  --teal:#5B7C99;
  --accent-grad:linear-gradient(120deg,#C9954E 0%,#9A6A2F 45%,#5B7C99 100%);
  --shadow-sm:0 1px 2px rgba(33,31,27,.05),0 4px 14px rgba(33,31,27,.06);
  --shadow-md:0 10px 40px rgba(33,31,27,.10);
  --radius:18px;
  --maxw:1120px;
  --serif:"Songti SC","STSong","Noto Serif SC",Georgia,"Times New Roman",serif;
  --sans:"PingFang SC","Hiragino Sans GB","Microsoft YaHei","Noto Sans SC",system-ui,-apple-system,Segoe UI,Roboto,sans-serif;
}

*{box-sizing:border-box;margin:0;padding:0}
html{scroll-behavior:smooth}
body{
  font-family:var(--sans);
  background:var(--paper);
  color:var(--ink);
  line-height:1.7;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
a{color:inherit;text-decoration:none}
h1,h2,h3{font-family:var(--serif);font-weight:600;letter-spacing:.01em;line-height:1.25;color:var(--ink)}

/* ---------- 按钮 ---------- */
.btn{
  display:inline-flex;align-items:center;justify-content:center;
  padding:13px 26px;border-radius:999px;font-weight:600;font-size:15px;
  transition:transform .18s ease,box-shadow .25s ease,background .25s ease;
  cursor:pointer;border:1px solid transparent;white-space:nowrap;
}
.btn-primary{background:var(--ink);color:var(--paper);box-shadow:var(--shadow-sm)}
.btn-primary:hover{transform:translateY(-2px);box-shadow:var(--shadow-md);background:#000}
.btn-ghost{background:transparent;border-color:var(--line);color:var(--ink)}
.btn-ghost:hover{border-color:var(--bronze);color:var(--bronze);transform:translateY(-2px)}
.btn-lg{padding:16px 38px;font-size:17px}

/* ---------- 导航 ---------- */
.nav{
  position:sticky;top:0;z-index:50;
  background:rgba(250,247,242,.82);
  backdrop-filter:saturate(160%) blur(12px);
  border-bottom:1px solid transparent;
  transition:border-color .3s ease,box-shadow .3s ease;
}
.nav.scrolled{border-color:var(--line);box-shadow:0 4px 20px rgba(33,31,27,.04)}
.nav-inner{
  max-width:var(--maxw);margin:0 auto;padding:14px 24px;
  display:flex;align-items:center;gap:24px;
}
.brand{display:flex;align-items:center;gap:10px;font-weight:700}
.brand-mark{color:var(--bronze);display:inline-flex;animation:spin 14s linear infinite}
.brand-name{font-family:var(--serif);font-size:20px;letter-spacing:.04em}
.brand-name em{font-style:normal;font-size:13px;color:var(--ink-3);font-family:var(--sans);margin-left:2px}
.nav-links{display:flex;gap:26px;margin-left:auto;font-size:15px;color:var(--ink-2)}
.nav-links a{position:relative;padding:4px 0;transition:color .2s}
.nav-links a:hover{color:var(--bronze)}
.nav-links a::after{content:"";position:absolute;left:0;bottom:-2px;width:0;height:2px;background:var(--accent-grad);transition:width .25s}
.nav-links a:hover::after{width:100%}
.nav-cta{padding:9px 20px;font-size:14px}

/* ---------- Hero ---------- */
.hero{position:relative;overflow:hidden;padding:96px 24px 60px;text-align:center}
.hero-rings{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;pointer-events:none}
.hero-rings span{
  position:absolute;border:1px solid var(--bronze);border-radius:50%;
  width:240px;height:240px;opacity:0;animation:echo 6s ease-out infinite;
}
.hero-rings span:nth-child(1){animation-delay:0s}
.hero-rings span:nth-child(2){animation-delay:1.2s}
.hero-rings span:nth-child(3){animation-delay:2.4s}
.hero-rings span:nth-child(4){animation-delay:3.6s}
.hero-rings span:nth-child(5){animation-delay:4.8s}
.hero-inner{position:relative;max-width:760px;margin:0 auto}
.eyebrow{
  display:inline-block;font-size:13px;letter-spacing:.22em;text-transform:uppercase;
  color:var(--bronze);font-weight:700;margin-bottom:18px;
}
.hero-title{font-size:clamp(34px,6vw,60px);margin-bottom:22px}
.hero-sub{font-size:clamp(16px,2.2vw,19px);color:var(--ink-2);max-width:600px;margin:0 auto 34px}
.hero-actions{display:flex;gap:14px;justify-content:center;flex-wrap:wrap}
.hero-trust{
  list-style:none;display:flex;gap:22px;justify-content:center;flex-wrap:wrap;
  margin-top:38px;font-size:14px;color:var(--ink-2);
}
.hero-trust li{display:flex;align-items:center;gap:8px}
.hero-trust .dot{width:7px;height:7px;border-radius:50%;background:var(--accent-grad)}

.waveband{margin-top:46px;width:100%;height:90px;color:var(--bronze)}
.waveband .wave{width:100%;height:100%}
.waveband path{
  fill:none;stroke:url(#g);stroke-width:2;opacity:.5;
  stroke-dasharray:1400;stroke-dashoffset:1400;animation:draw 4s ease forwards,wave 5s ease-in-out 4s infinite;
}
.waveband svg{width:100%;height:100%}

/* ---------- 通用 section ---------- */
.section{max-width:var(--maxw);margin:0 auto;padding:88px 24px}
.section-alt{background:var(--paper-2);max-width:none}
.section-alt > *{max-width:var(--maxw);margin-left:auto;margin-right:auto}
.section-head{text-align:center;max-width:680px;margin:0 auto 52px}
.section-head h2{font-size:clamp(26px,4vw,40px);margin:6px 0 14px}
.section-lead{color:var(--ink-2);font-size:17px}

/* ---------- 功能网格 ---------- */
.feature-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:20px}
.card{
  background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  padding:28px 24px;box-shadow:var(--shadow-sm);
  transition:transform .22s ease,box-shadow .25s ease,border-color .25s ease;
  opacity:0;transform:translateY(18px);
}
.card.in{opacity:1;transform:none}
.card:hover{transform:translateY(-6px);box-shadow:var(--shadow-md);border-color:var(--bronze-soft)}
.card-ico{
  width:48px;height:48px;border-radius:14px;display:flex;align-items:center;justify-content:center;
  color:var(--bronze);background:var(--paper-2);margin-bottom:16px;
}
.card-ico svg{width:26px;height:26px;display:block}
.card h3{font-size:19px;margin-bottom:8px}
.card p{color:var(--ink-2);font-size:14.5px;line-height:1.65}

/* ---------- 工作方式 steps ---------- */
.steps{display:flex;align-items:stretch;gap:8px;flex-wrap:wrap;justify-content:center}
.step{
  flex:1 1 200px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);
  padding:30px 24px;text-align:center;box-shadow:var(--shadow-sm);
  opacity:0;transform:translateY(18px);transition:opacity .5s,transform .5s;
}
.step.in{opacity:1;transform:none}
.step-num{
  font-family:var(--serif);font-size:30px;font-weight:700;
  background:var(--accent-grad);-webkit-background-clip:text;background-clip:text;color:transparent;
  margin-bottom:10px;
}
.step h3{font-size:20px;margin-bottom:8px}
.step p{color:var(--ink-2);font-size:14.5px}
.step-arrow{display:flex;align-items:center;font-size:26px;color:var(--bronze);opacity:.6}

/* ---------- 隐私 split ---------- */
.split{display:grid;grid-template-columns:1.1fr .9fr;gap:56px;align-items:center}
.split-text h2{font-size:clamp(26px,4vw,38px);margin:6px 0 16px}
.check-list{list-style:none;margin-top:24px;display:grid;gap:14px}
.check-list li{position:relative;padding-left:32px;color:var(--ink-2);font-size:15.5px}
.check-list li::before{
  content:"";position:absolute;left:0;top:7px;width:18px;height:18px;border-radius:50%;
  background:var(--accent-grad);
  -webkit-mask:url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'><path fill='white' d='M9 16.2 4.8 12l-1.4 1.4L9 19 21 7l-1.4-1.4z'/></svg>") center/14px no-repeat;
  mask:url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24'><path fill='white' d='M9 16.2 4.8 12l-1.4 1.4L9 19 21 7l-1.4-1.4z'/></svg>") center/14px no-repeat;
}
.split-visual{display:flex;justify-content:center}
.shield{color:var(--bronze);text-align:center;display:flex;flex-direction:column;align-items:center;gap:14px}
.shield svg{filter:drop-shadow(0 8px 20px rgba(154,106,47,.18))}
.shield-label{font-size:13px;letter-spacing:.12em;color:var(--ink-3);text-transform:uppercase}

/* ---------- 语言 ---------- */
.lang-row{display:flex;flex-wrap:wrap;gap:12px;justify-content:center;max-width:760px;margin:0 auto}
.lang-row span{
  background:var(--surface);border:1px solid var(--line);border-radius:999px;
  padding:12px 26px;font-size:16px;color:var(--ink);box-shadow:var(--shadow-sm);
  transition:transform .2s,border-color .2s,color .2s;
}
.lang-row span:hover{transform:translateY(-3px);border-color:var(--bronze);color:var(--bronze)}

/* ---------- CTA ---------- */
.cta{padding:96px 24px;text-align:center;background:var(--ink);color:var(--paper)}
.cta-inner{max-width:640px;margin:0 auto}
.cta h2{color:var(--paper);font-size:clamp(28px,4.5vw,44px);margin-bottom:16px}
.cta p{color:#C9C2B6;font-size:17px;margin-bottom:30px}
.cta .btn-primary{background:var(--paper);color:var(--ink)}
.cta .btn-primary:hover{background:#fff}
.cta-note{margin-top:26px;font-size:13px;letter-spacing:.14em;color:#8C857A;text-transform:uppercase}

/* ---------- 页脚 ---------- */
.footer{background:var(--paper-2);border-top:1px solid var(--line)}
.footer-inner{
  max-width:var(--maxw);margin:0 auto;padding:48px 24px 28px;
  display:flex;justify-content:space-between;gap:30px;flex-wrap:wrap;
}
.footer-brand p{color:var(--ink-2);font-size:14px;margin-top:10px;max-width:280px}
.footer-links{display:flex;gap:24px;flex-wrap:wrap;align-items:flex-start;font-size:15px;color:var(--ink-2)}
.footer-links a:hover{color:var(--bronze)}
.footer-bottom{
  max-width:var(--maxw);margin:0 auto;padding:18px 24px;border-top:1px solid var(--line);
  display:flex;justify-content:space-between;gap:16px;flex-wrap:wrap;
  font-size:13px;color:var(--ink-3);
}

/* ---------- 动效 ---------- */
@keyframes spin{to{transform:rotate(360deg)}}
@keyframes echo{
  0%{transform:scale(.5);opacity:.5}
  100%{transform:scale(3.2);opacity:0}
}
@keyframes draw{to{stroke-dashoffset:0}}
@keyframes wave{
  0%,100%{transform:translateY(0)}
  50%{transform:translateY(-6px)}
}
.reveal{opacity:0;transform:translateY(22px);transition:opacity .7s ease,transform .7s ease}
.reveal.in{opacity:1;transform:none}

/* ---------- 响应式 ---------- */
@media (max-width:980px){
  .feature-grid{grid-template-columns:repeat(2,1fr)}
  .split{grid-template-columns:1fr;gap:36px}
  .nav-links{display:none}
}
@media (max-width:560px){
  .hero{padding:72px 18px 40px}
  .feature-grid{grid-template-columns:1fr}
  .step-arrow{transform:rotate(90deg)}
  .section{padding:64px 18px}
  .footer-inner{flex-direction:column}
  .nav-cta{display:none}
}

@media (prefers-reduced-motion:reduce){
  *{animation:none!important;transition:none!important}
  .reveal,.card,.step{opacity:1!important;transform:none!important}
}

/* ---------- 弹层：即将到来 ---------- */
.modal{
  position:fixed;inset:0;z-index:100;
  display:flex;align-items:center;justify-content:center;
  padding:24px;visibility:hidden;opacity:0;
  transition:opacity .28s ease,visibility .28s ease;
}
.modal.open{visibility:visible;opacity:1}
.modal-backdrop{
  position:absolute;inset:0;
  background:rgba(33,31,27,.42);
  backdrop-filter:blur(6px);-webkit-backdrop-filter:blur(6px);
}
.modal-card{
  position:relative;z-index:1;width:min(420px,100%);
  background:var(--surface);border:1px solid var(--line);border-radius:24px;
  padding:40px 34px 34px;text-align:center;box-shadow:var(--shadow-md);
  transform:translateY(16px) scale(.98);
  transition:transform .32s cubic-bezier(.2,.8,.25,1);
}
.modal.open .modal-card{transform:none}
.modal-close{
  position:absolute;top:14px;right:14px;width:34px;height:34px;
  display:flex;align-items:center;justify-content:center;
  border:none;background:transparent;color:var(--ink-3);cursor:pointer;border-radius:50%;
  transition:color .2s,background .2s;
}
.modal-close:hover{color:var(--ink);background:var(--paper-2)}
.modal-close svg{width:20px;height:20px}
.modal-mark{color:var(--bronze);display:flex;justify-content:center;margin-bottom:18px}
.modal-mark svg{animation:echoMark 3.2s ease-in-out infinite}
@keyframes echoMark{0%,100%{transform:scale(1);opacity:.92}50%{transform:scale(1.06);opacity:1}}
.modal-title{font-size:26px;margin-bottom:12px}
.modal-text{color:var(--ink-2);font-size:15px;line-height:1.7;margin-bottom:26px}
.modal-cta{width:100%;text-decoration:none}