:root{--navy:#0B2545;--blue:#1D4E89;--ink:#0F172A;--muted:#5A6B85;
  --line:#E2E8F0;--bg:#F7F9FC;--card:#FFFFFF}
*{box-sizing:border-box}
body{margin:0;background:var(--bg);color:var(--ink);
  font:16px/1.7 -apple-system,BlinkMacSystemFont,"Segoe UI",Inter,Roboto,Helvetica,Arial,sans-serif}
header{background:linear-gradient(180deg,var(--blue),var(--navy));padding:18px 0}
.wrap{max-width:760px;margin:0 auto;padding:0 20px}
.brand{display:flex;align-items:center;gap:12px;color:#fff;font-weight:700;
  font-size:19px;text-decoration:none}
.brand img{width:34px;height:34px;border-radius:8px;display:block}
main{background:var(--card);border:1px solid var(--line);border-radius:12px;
  padding:34px;margin:26px auto 30px;max-width:760px}
h1{font-size:31px;line-height:1.25;margin:0 0 10px;letter-spacing:-.5px}
h2{font-size:21px;margin:34px 0 10px;letter-spacing:-.2px}
h3{font-size:17px;margin:24px 0 6px}
p,li{color:#26374F}
.lede{font-size:18px;color:#33455F}
code{background:#EEF3F9;padding:2px 6px;border-radius:4px;font-size:14px;
  font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace}
pre{background:#0F2038;color:#D6E4F7;padding:15px;border-radius:9px;
  overflow-x:auto;font-size:13.5px;line-height:1.55;
  font-family:ui-monospace,SFMono-Regular,Menlo,Consolas,monospace}
pre code{background:none;padding:0;color:inherit;font-size:inherit}
table{border-collapse:collapse;width:100%;margin:14px 0;font-size:14.5px}
th,td{text-align:left;padding:9px 10px;border-bottom:1px solid var(--line);
  vertical-align:top}
th{color:var(--muted);font-weight:600}
.callout{border-left:3px solid var(--blue);background:#F1F6FC;padding:13px 15px;
  border-radius:0 8px 8px 0;margin:18px 0}
.checker{border:1px solid var(--line);border-radius:11px;padding:20px;margin:26px 0;
  background:#FBFDFF}
form{display:flex;gap:9px;flex-wrap:wrap}
input[type=text]{flex:1 1 260px;min-width:0;padding:12px 14px;font-size:16px;
  border:1.5px solid var(--line);border-radius:8px}
input[type=text]:focus{outline:none;border-color:var(--blue)}
button{padding:12px 20px;font-size:16px;font-weight:600;color:#fff;
  background:var(--blue);border:0;border-radius:8px;cursor:pointer}
button:disabled{opacity:.6;cursor:progress}
#out{margin-top:15px;font-size:15px}
.res{padding:13px 15px;border-radius:9px;border:1px solid var(--line);background:#fff}
.res.bad{border-color:#F3C6C6;background:#FDF2F2}
.res.good{border-color:#C6E7CE;background:#F2FBF4}
.res b{display:block;margin-bottom:4px}
.chain{font-size:13px;color:var(--muted);margin-top:7px;word-break:break-all}
.more{margin-top:34px;padding-top:20px;border-top:1px solid var(--line)}
.more h2{margin-top:0}
.more ul{padding-left:20px}
footer{padding:0 0 40px;color:var(--muted);font-size:13.5px}
a{color:var(--blue)}
@media (max-width:600px){main{padding:22px;border-radius:0}h1{font-size:26px}}