:root{color-scheme:light;--ink:#17263d;--muted:#526177;--blue:#153c78;--paper:#f5f7fb;--line:#dce3ec;--white:#fff}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:24px}
body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.65 system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}
a{color:var(--blue);text-underline-offset:3px}
a:hover{text-decoration:underline}
header,footer{max-width:1140px;margin:auto;padding:22px 36px;display:flex;align-items:center;justify-content:space-between;gap:24px}
header{border-bottom:1px solid var(--line)}
.brand{text-decoration:none;font-weight:750;font-size:17px;letter-spacing:-.4px;display:flex;align-items:center;gap:10px;white-space:nowrap;color:var(--ink)}
.aperture{display:inline-block;position:relative;flex:none;width:.95em;height:.95em;font-size:26px;line-height:0;color:transparent;border:.13em solid var(--blue);border-radius:50%;box-sizing:border-box;overflow:hidden;user-select:none}.aperture::before{content:"";position:absolute;inset:.13em;border-radius:50%;background:var(--blue)}
nav{display:flex;gap:24px;flex-wrap:wrap}
nav a{font-size:14px;color:var(--muted);text-decoration:none}
header .home-link{font-weight:650;color:var(--blue);white-space:nowrap}
main{max-width:1040px;margin:42px auto 56px;padding:0 32px}
.intro{text-align:center;max-width:760px;margin:0 auto 26px}
h1{font-size:clamp(32px,4vw,48px);line-height:1.18;font-weight:780;letter-spacing:-1.8px;margin:0 0 16px}
.lead{max-width:680px;margin:0 auto;color:var(--muted);font-size:17px}
.tool-facts{display:flex;flex-wrap:wrap;justify-content:center;gap:8px 20px;list-style:none;padding:0;margin:18px 0 0;font-size:13px;color:var(--muted)}
.tool-facts li:before{content:'✓';margin-right:6px;color:var(--blue)}
h2{font-size:25px;line-height:1.3;letter-spacing:-.6px;margin:0 0 16px}
h3{font-size:17px;line-height:1.4;margin:0 0 8px;letter-spacing:-.2px}
p{margin:0 0 12px}
code{font-family:ui-monospace,SFMono-Regular,Consolas,monospace;font-size:13px;background:#eaf0f8;padding:1px 5px;border-radius:4px}
button{font:inherit;cursor:pointer}
.primary{background:var(--blue);color:white;border:0;border-radius:6px;font-size:15px;font-weight:650;padding:12px 24px;margin:18px 0 14px;min-height:48px}
.primary:hover{background:#102e5a}
.primary:disabled{opacity:.6;cursor:wait}
.secondary{border:1px solid var(--line);padding:10px 16px;border-radius:6px;background:#eaf0f8;color:var(--blue);font:inherit;font-size:14px;cursor:pointer;margin:0}
button:focus-visible,a:focus-visible,summary:focus-visible,input:focus-visible,select:focus-visible,textarea:focus-visible{outline:3px solid #3273d3;outline-offset:4px}
.checker{max-width:900px;margin:0 auto;background:var(--white);border:1px solid var(--line);padding:22px;border-radius:12px;box-shadow:0 6px 24px #17263d06}
.checker.code-tool{max-width:900px}
.code-tool label{display:block;font-weight:650;margin:16px 0 8px;font-size:15px}
.code-tool textarea{display:block;width:100%;min-height:230px;padding:14px;font:13px/1.6 ui-monospace,SFMono-Regular,Consolas,monospace;color:var(--ink);border:1px solid var(--line);border-radius:7px;resize:vertical;tab-size:2}
.code-tool textarea:focus-visible{outline:2px solid var(--blue);outline-offset:2px}
.code-tool input[type=text]{display:block;width:100%;font:inherit;font-size:15px;border:1px solid var(--line);border-radius:6px;padding:10px;background:#fff;color:var(--ink);margin-top:7px}
.code-tool select{display:block;width:100%;font:inherit;font-size:15px;border:1px solid var(--line);border-radius:6px;padding:10px;background:#fff;color:var(--ink);margin-top:7px}
.code-tool input[type=file]{display:block;width:100%;font:inherit;font-size:14px;color:var(--ink);margin-top:4px}
.controls{display:flex;gap:10px;flex-wrap:wrap;align-items:center;margin:16px 0}
.notice{color:#9b2929;font-weight:600;white-space:pre-wrap;overflow-wrap:anywhere}
.status{color:var(--muted);font-size:14px;min-height:24px}
.subtle{font-size:13px;color:var(--muted)}
.json-options{display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:8px 20px;align-items:start;margin:6px 0 4px}
.json-options .option-field label{display:block;font-weight:650;margin:16px 0 8px;font-size:14px}
.json-options .checkbox-list{grid-column:1/-1;display:grid;grid-template-columns:minmax(0,1fr) minmax(0,1fr);gap:2px 20px;margin:8px 0 0}
.json-options .checkbox{display:flex;align-items:center;gap:10px;font-weight:650;font-size:14px;margin:4px 0;cursor:pointer;min-height:32px}
.json-options .checkbox input{accent-color:var(--blue);width:18px;height:18px;margin:0;flex-shrink:0}
.json-options .checkbox code{font-weight:400}
.code-tool .download{display:inline-block;width:auto;margin:0;text-decoration:none}
.code-tool .download:hover{text-decoration:none;color:#fff}
#result{border-top:1px solid var(--line);padding-top:22px;margin-top:22px}
#result h2{font-size:21px;margin:0 0 8px}
#output{min-height:300px}
.content-section{max-width:760px;margin:48px auto 0}
.content-section>p{color:var(--muted)}
.content-section h2{font-size:25px}
.steps{counter-reset:steps;list-style:none;display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:28px;padding:0;margin:24px 0 0}
.steps li{counter-increment:steps}
.steps+p{margin-top:28px}
.steps li:before{content:counter(steps);display:grid;place-items:center;width:30px;height:30px;margin-bottom:14px;border-radius:6px;background:#e8effa;color:var(--blue);font-size:14px;font-weight:700}
.steps p,.explanation-grid p{color:var(--muted);font-size:15px;margin-bottom:0}
.explanation-grid{display:grid;grid-template-columns:1fr 1fr;gap:36px}
.explanation-grid p+p{margin-top:12px}
.table-wrap{margin:24px 0 16px;border:1px solid var(--line);border-radius:8px;overflow-x:auto}
table{width:100%;border-collapse:collapse;text-align:left;font-size:14px;line-height:1.6}
caption{text-align:left;padding:14px 18px;font-size:13px;color:var(--muted);background:var(--white)}
thead{background:#eaf0f8}
th,td{padding:13px 18px;vertical-align:top}
tbody th{font-weight:650;width:23%}
tbody td{color:var(--muted)}
tbody tr{background:var(--white);border-top:1px solid var(--line)}
td:nth-child(2){width:30%}
td code{background:#eef3fa}
.faq h2{margin-bottom:22px}
details{border-top:1px solid var(--line);padding:18px 0}
details:last-child{border-bottom:1px solid var(--line)}
summary{font-size:16px;font-weight:600;cursor:pointer}
details p{font-size:15px;color:var(--muted);margin:12px 0 0;max-width:870px}
.related{list-style:none;padding:0;margin:0;display:grid;gap:14px}
.related li{color:var(--muted);font-size:15px}
.related a{font-weight:650}
.skip-link{position:absolute;top:8px;left:8px;background:var(--white);padding:8px 16px;z-index:10;transform:translateY(-200%)}
.skip-link:focus{transform:none}
[hidden]{display:none!important}
footer{border-top:1px solid var(--line);font-size:13px;color:var(--muted)}
footer a{color:var(--ink);text-decoration:none;font-weight:600}
.footer-links{display:flex;gap:20px;flex-wrap:wrap}
.footer-links a{font-size:13px}
@media(max-width:720px){
header{padding:18px 22px;display:block}
.brand{font-size:16px}
nav{margin-top:16px;gap:14px}
nav a{font-size:13px}
main{margin:28px auto 40px;padding:0 20px}
h1{font-size:32px;letter-spacing:-1px}
.lead{font-size:16px}
.tool-facts{gap:5px 14px;font-size:12px}
.checker{padding:14px}
.code-tool textarea{min-height:180px}
.primary{width:100%;max-width:none;text-align:center}
.controls>*{flex:1 1 auto;text-align:center}
.json-options{grid-template-columns:1fr}
.json-options .checkbox-list{grid-template-columns:1fr;margin-top:4px}
.content-section{margin-top:32px}
.content-section h2{font-size:23px}
.steps{grid-template-columns:1fr;gap:24px}
.steps li{display:grid;grid-template-columns:30px 1fr;column-gap:14px}
.steps li:before{grid-row:1/3;margin-top:2px}
.steps p,.steps h3{grid-column:2}
.explanation-grid{grid-template-columns:1fr;gap:28px}
caption{padding:12px}
th,td{padding:9px 8px;font-size:12px;overflow-wrap:anywhere}
table{table-layout:fixed}
tbody th{width:30%}
td:nth-child(2){width:34%}
footer{padding:22px;display:block;font-size:12px}
.footer-links{margin-top:14px}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}