:root{
  --brand-900:#001A66; --brand-700:#0033CC; --brand-500:#3366DD;
  --brand-100:#D6E2FF; --brand-50:#EEF2FF;
  --n900:#1A1A1A; --n600:#585858; --n400:#999999; --n200:#E5E5E5; --n100:#F5F5F5; --n0:#FFFFFF;
  --border:rgba(0,0,0,.09);
  --sans:"Inter",system-ui,-apple-system,"Segoe UI",Roboto,sans-serif;
  --max:1040px;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth}
body{
  margin:0;font-family:var(--sans);color:var(--n900);background:var(--n0);
  -webkit-font-smoothing:antialiased;line-height:1.5;
}
a{color:inherit;text-decoration:none}
h1,h2,h3,h4{margin:0;font-weight:600;letter-spacing:-0.02em}
p{margin:0}
ol{margin:0;padding:0;list-style:none}
img{display:block;max-width:100%}
::selection{background:var(--brand-700);color:#fff}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;
  border-radius:10px;font-weight:600;white-space:nowrap;transition:background .15s ease,transform .1s ease}
.btn:active{transform:translateY(1px)}
.btn-primary{background:var(--brand-700);color:#fff}
.btn-primary:hover{background:var(--brand-500)}
.btn-ghost{background:transparent;color:var(--n900);border:1px solid var(--border)}
.btn-ghost:hover{background:var(--n100)}
.btn-sm{padding:8px 16px;font-size:14px}
.btn-lg{padding:14px 26px;font-size:16px}

/* ---------- Nav ---------- */
.nav{
  display:flex;align-items:center;justify-content:space-between;gap:24px;
  max-width:var(--max);margin:0 auto;padding:20px 24px;
  position:sticky;top:0;z-index:100;background:var(--n0);
  border-bottom:1px solid var(--border);
}
.brand{display:flex;align-items:center;gap:10px;font-weight:600;font-size:16px;color:var(--brand-900)}
.brand-mark{width:28px;height:28px;border-radius:7px}
.nav-links{display:flex;align-items:center;gap:28px}
.nav-links a{color:var(--n600);font-weight:500;font-size:14px}
.nav-links a:hover{color:var(--brand-700)}
.nav-download{border:1px solid var(--brand-700);border-radius:8px;padding:6px 12px}
.nav-download:hover{background:var(--brand-50)}
.icon-link{display:flex;color:var(--n600)}
.icon-link:hover{color:var(--brand-700)}
.btn-donate{background:var(--brand-700);color:#fff}
.btn-donate:hover{background:var(--brand-500)}

/* ---------- Hero ---------- */
.hero{
  max-width:var(--max);margin:0 auto;padding:64px 24px 40px;text-align:center;
}
.hero h1{font-size:42px;line-height:1.08;color:var(--n900)}
.lede{margin:22px auto 0;max-width:560px;font-size:18px;color:var(--n600);line-height:1.55}
.hero-ctas{display:flex;gap:14px;justify-content:center;margin-top:32px;flex-wrap:wrap}
.hero-note{margin-top:16px;font-size:13px;color:var(--n400);letter-spacing:.02em}
.hero-list{max-width:420px;margin:24px auto 0;text-align:left}

/* ---------- Demo chat mock ---------- */
.demo{
  max-width:520px;margin:56px auto 0;border-radius:16px;border:1px solid var(--border);
  background:var(--n0);box-shadow:0 20px 60px -20px rgba(0,26,102,.25);overflow:hidden;text-align:left;
}
.demo-bar{display:flex;align-items:center;gap:6px;padding:12px 14px;background:var(--brand-50);
  border-bottom:1px solid var(--border)}
.demo-dot{width:9px;height:9px;border-radius:50%;background:var(--n200)}
.demo-status{margin-left:auto;display:flex;align-items:center;gap:6px;font-size:12px;font-weight:600;color:var(--brand-700)}
.rec-dot{width:7px;height:7px;border-radius:50%;background:#E53E3E;animation:pulse 1.6s ease-in-out infinite}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.35}}
.demo-body{display:flex;flex-direction:column;gap:10px;padding:20px}
.bubble{max-width:78%;padding:10px 14px;border-radius:14px;font-size:14px;line-height:1.45;position:relative}
.bubble-label{display:block;font-size:10px;font-weight:700;text-transform:uppercase;letter-spacing:.06em;
  opacity:.6;margin-bottom:2px}
.bubble.them{align-self:flex-start;background:var(--n100);color:var(--n900);border-bottom-left-radius:4px}
.bubble.me{align-self:flex-end;background:var(--brand-700);color:#fff;border-bottom-right-radius:4px}

/* ---------- Sub-page header ---------- */
.page-header{max-width:var(--max);margin:0 auto;padding:64px 24px 0;text-align:center}
.page-header h1{font-size:42px;color:var(--n900)}

/* ---------- About ---------- */
.notice{max-width:640px;margin:32px auto 0;padding:20px 24px;border-radius:12px;
  background:var(--brand-50);border:1px solid var(--brand-100);text-align:left}
section.notice{margin-bottom:64px}
.notice h3{font-size:15px;color:var(--brand-900);margin-bottom:8px}
.notice h4{font-size:13px;color:var(--brand-900);margin:20px 0 8px}
.notice p{font-size:14px;color:var(--n600);line-height:1.6}
.notice p + p, .notice .check-list{margin-top:12px}
.notice .check-list li{font-size:14px}
.about{max-width:var(--max);margin:0 auto;padding:40px 24px 96px}
.about h2{font-size:32px;text-align:center}
.lede-block{max-width:640px;margin:18px auto 0;font-size:16px;color:var(--n600);line-height:1.65;text-align:center}
.about-grid{display:grid;grid-template-columns:repeat(2,1fr);gap:48px;margin-top:56px}
.about-block h3{font-size:18px;color:var(--brand-900)}
.about-block p{margin-top:12px;font-size:14.5px;color:var(--n600);line-height:1.65}
.check-list{margin-top:12px;padding:0;list-style:none;display:flex;flex-direction:column;gap:10px}
.check-list li{font-size:14.5px;color:var(--n600);line-height:1.6;padding-left:22px;position:relative}
.check-list li::before{content:"";position:absolute;left:0;top:7px;width:8px;height:8px;border-radius:50%;background:var(--brand-100);border:2px solid var(--brand-700)}
.about-block code{background:var(--n100);padding:1px 6px;border-radius:5px;font-size:13px}

/* ---------- Features ---------- */
.features{
  max-width:var(--max);margin:0 auto;padding:96px 24px;
  display:grid;grid-template-columns:repeat(4,1fr);gap:36px;
}
.feature h3{font-size:17px;color:var(--brand-900)}
.feature p{margin-top:10px;font-size:14.5px;color:var(--n600);line-height:1.6}

/* ---------- Information (docs-style) ---------- */
.info{background:var(--brand-50);padding:56px 24px 88px}
.info-toc{max-width:var(--max);margin:0 auto;display:flex;justify-content:center;gap:14px;
  flex-wrap:wrap;padding:10px 0;border-bottom:1px solid var(--border);
  position:sticky;top:78px;z-index:90;background:var(--brand-50)}
.info-toc a{font-size:14px;font-weight:600;color:var(--brand-700)}
.info-toc a:hover{color:var(--brand-900);text-decoration:underline}
.info-block{max-width:640px;margin:0 auto;padding-top:56px}
.info-block h3{font-size:20px;color:var(--brand-900);margin-bottom:20px}
.info-block h4{font-size:15px;color:var(--brand-900);margin:24px 0 8px}
#info-consent p a{color:var(--brand-700);text-decoration:underline}
#info-consent p a:hover{color:var(--brand-900)}

.steps{display:grid;grid-template-columns:repeat(3,1fr);gap:32px;text-align:left}
.steps li{text-align:left}
.step-num{display:inline-flex;align-items:center;justify-content:center;width:32px;height:32px;
  border-radius:50%;background:var(--brand-100);color:var(--brand-700);font-weight:700;font-size:14px;margin-bottom:16px}
.steps h4{font-size:16px;margin-bottom:8px}
.steps p{font-size:14.5px;color:var(--n600);line-height:1.6}

.reqs-table{width:100%;border-collapse:collapse;background:var(--n0);border-radius:12px;overflow:hidden;
  border:1px solid var(--border)}
.reqs-table tr:not(:last-child){border-bottom:1px solid var(--border)}
.reqs-table th,.reqs-table td{text-align:left;padding:12px 16px;font-size:14px;font-weight:400}
.reqs-table th{color:var(--n900);font-weight:600;width:35%;background:var(--n100)}
.reqs-table td{color:var(--n600)}

.info-block p{font-size:15px;color:var(--n600);line-height:1.65}

.info-block details{background:var(--n0);border:1px solid var(--border);border-radius:10px;
  padding:14px 16px;margin-bottom:10px}
.info-block details[open]{padding-bottom:16px}
.info-block summary{cursor:pointer;font-weight:600;font-size:14.5px;color:var(--n900)}
.info-block details p{margin-top:10px;font-size:14px}

.consent-note{max-width:var(--max);margin:32px auto 0;padding:0 24px;text-align:center;font-size:14px;color:var(--n400)}
.consent-note a{color:var(--brand-700);font-weight:600}
.consent-note a:hover{color:var(--brand-900);text-decoration:underline}

/* ---------- Donate note ---------- */
.donate-note{max-width:var(--max);margin:0 auto;padding:32px 24px;text-align:center}
.donate-note p{font-size:14px;color:var(--n400)}
.donate-note a{color:var(--brand-700);font-weight:600}
.donate-note a:hover{color:var(--brand-900);text-decoration:underline}

/* ---------- Download ---------- */
.download{max-width:var(--max);margin:0 auto;padding:96px 24px;text-align:center}
.download h2{font-size:32px}
.download p{margin-top:14px;color:var(--n600);font-size:15px}
.download .btn{margin-top:28px}
.download .hero-note{margin-top:14px}

/* ---------- Footer ---------- */
.footer{
  border-top:1px solid var(--border);padding:28px 24px;text-align:center;
  font-size:13px;color:var(--n400);
  display:flex;flex-direction:column;gap:6px;
}
.footer-credit a, .footer-contact a{color:var(--brand-700);text-decoration:underline}
.footer-credit a:hover, .footer-contact a:hover{color:var(--brand-900)}

/* ---------- Responsive ---------- */
@media (max-width:860px){
  .nav-links{display:none}
  .hero h1{font-size:38px}
  .features{grid-template-columns:repeat(2,1fr);gap:32px}
  .steps{grid-template-columns:1fr;gap:32px}
  .about-grid{grid-template-columns:1fr;gap:36px}
}
@media (max-width:480px){
  .features{grid-template-columns:1fr}
  .hero-ctas{flex-direction:column;align-items:center}
}