:root{--ink:#1b2030;--mut:#66708a;--line:#e3e6ee;--bg:#f4f5f9;--card:#fff;--acc:#1f6f54;--acc-soft:#e5f2ec;--bad:#b0221a}*{box-sizing:border-box}body{margin:0;font:16px/1.6 system-ui,-apple-system,Segoe UI,sans-serif;background:var(--bg);color:var(--ink)}a{color:var(--acc);text-decoration:none}a:hover{text-decoration:underline}header.top{display:flex;justify-content:space-between;align-items:center;padding:14px 22px;background:#fff;border-bottom:1px solid var(--line);position:-webkit-sticky;position:sticky;top:0;z-index:20}.brand{font-weight:800;letter-spacing:.14em;color:var(--ink);font-size:15px}header.top nav{display:flex;gap:18px;align-items:center;font-size:14.5px}main{max-width:960px;margin:0 auto;padding:30px 18px 70px}.hero{text-align:center;padding:46px 0 30px}.hero h1{font-size:34px;line-height:1.25;margin:0 0 14px;text-wrap:balance}.hero p.lead{font-size:18px;color:var(--mut);max-width:640px;margin:0 auto 26px}.btn{display:inline-block;background:var(--acc);color:#fff!important;font-weight:700;border:none;border-radius:10px;padding:12px 26px;font-size:15.5px;cursor:pointer;text-decoration:none!important}.btn:hover{filter:brightness(1.08)}.btn.sm{padding:8px 16px;font-size:14px}.btn.ghost{background:var(--acc-soft);color:var(--acc)!important}.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:22px;margin-bottom:16px}.grid3{display:grid;grid-template-columns:repeat(3,1fr);grid-gap:14px;gap:14px}@media (max-width:760px){.grid3{grid-template-columns:1fr}.hero h1{font-size:26px}}.step-num{display:inline-flex;width:30px;height:30px;border-radius:50%;background:var(--acc-soft);color:var(--acc);font-weight:800;align-items:center;justify-content:center;margin-bottom:8px}.muted{color:var(--mut)}.small,label{font-size:13.5px}label{display:block;font-weight:600;color:var(--mut);margin-bottom:4px}input[type=tel],input[type=text]{width:100%;padding:11px 13px;border:1px solid var(--line);border-radius:10px;font:inherit;margin-bottom:14px}.check{display:flex;gap:9px;align-items:flex-start;font-size:14px;margin:10px 0}.check input{margin-top:4px}.err{color:var(--bad)}.err,.ok-msg{font-size:14px;margin:8px 0}.ok-msg{color:var(--acc)}footer.foot{border-top:1px solid var(--line);background:#fff;padding:22px;text-align:center;font-size:13px;color:var(--mut);display:grid;grid-gap:6px;gap:6px}.doc h1{font-size:24px}.doc .meta{color:var(--mut);font-size:13.5px}.chain-demo{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;margin:26px 0;font-size:13.5px}.chain-node{background:#fff;border:1.5px solid var(--acc);color:var(--acc);border-radius:999px;padding:7px 14px;font-weight:600}.chain-arrow{align-self:center;color:var(--mut)}